feat: extract lambdas/shared/ — single-source ses_auth, web_ui auth, email parsing, EMF emitter (refactor phase 3) (#111)

Four modules move into the handbook-mandated lambdas/shared/ location,
collapsing duplicated logic that had to be kept in sync by hand across
the PO and WO pipelines:

- ses_auth.py: the PO and WO copies were verified sha256-identical
  against the feature/phase-7-ops-recovery baseline before the move
  (no drift since the last audit). shared/ses_auth.py is the exact
  bytes of that one copy; both originals are git rm'd (the PO copy
  via rename, the WO copy as a straight delete). Bundling lands the
  module flat in /asset-output for both email processors, so the
  handlers keep `from ses_auth import authenticate_inbound_email`
  unchanged — zero handler diff for this move, which is what keeps
  fail-closed auth byte-identical through the change.

- web_ui_auth.py: extracts the byte-identical _get_auth_token /
  _header / is_authenticated block plus the four token-cache globals
  out of both web_ui handlers. The per-stack INFRA-74 comments stay
  in each handler as-is (deliberately drifted wording, stack-specific)
  rather than being unified into the shared module. Fail-closed
  semantics (unset ARN or Secrets Manager exception -> deny) are
  unchanged.

- email_parsing.py: parse_raw_email ships as the superset version that
  returns cc unconditionally. WO's output is bit-identical to before;
  PO simply ignores the cc field rather than being "cleaned up" to
  consume it. No second variant is kept.

- emf.py: a generic emitter parameterized by namespace, dimension
  sets, and properties. Every call site's emitted EMF envelope is
  unchanged, including the load-bearing
  [["ParseMethod"],["ParseMethod","TemplateId"]] dimension-set shape
  the alarms and metric filters depend on. Emission ordering is
  untouched: PO still emits ai_fallback before the Bedrock call, WO
  still emits its mutually-exclusive ai_fallback/ai_fallback_rejected
  after its gate. The deliberate-double-count comments survive.
  _emit_derived_agreement_metric was found living inside
  derived_fields.py, so per the DERIVED-FIELDS exception it is left
  as a third, unconverted copy (derived_fields.py and the shadow
  DerivedFieldAgreement telemetry stay untouchable while that bake
  runs) — a comment there points at shared/emf.py for the eventual
  follow-up.

Bundling: both email-processor cdk bundling commands gain a trailing
`cp shared/*.py /asset-output/` (they were already cp-only post-Phase
7, so no pip step or manylinux pin is reintroduced). Both web_ui
functions gain the same widened-root staging so web_ui_auth.py ships
beside their handler; site_extractor's from_asset is untouched.

Tests: PO_EXPECTED_TOP_LEVEL_MODULES gains the shared modules that now
ship, the AST sibling-import check resolves imports whose source now
lives under shared/, and the new shared cp line has its own
revert/mutation detection. _SIBLING_MODULES resolution and
_po_parser_support.py now load ses_auth/email_parsing/emf from
shared/; the two-copy ses_auth byte-identity fixture-hygiene test is
retired as obsolete now that there is one copy, and the ses_auth
fixture parameterization over two identical copies is dropped. The
sys.modules save/restore dance for template_parser (still duplicated
per-pipeline) is left in place.

.claude/workflows/phase-3-shared-extraction.js

@@ -0,0 +1,679 @@
+export const meta = {
+  name: 'phase-3-shared-extraction',
+  description: 'Phase 3 of the procurement-ingest refactor (docs/refactor-evaluation.md): extract lambdas/shared/ — ses_auth.py (byte-identical move, zero handler diff), web_ui_auth.py (byte-identical auth block from both web_ui handlers), email_parsing.py (parse_raw_email superset, cc unconditional), emf.py (parameterized emitter preserving every envelope byte-for-byte). Bundling gains cp shared/*.py in both email-processor commands + the same staging mechanism for both web_ui functions. Requires Phases 0-2 on the base branch. Auth code moves, so push is gated on /sh-security-review in the main loop. Committed locally, never pushed.',
+  phases: [
+    { title: 'Setup', detail: 'verify Phases 0+1+2 on base, branch feature/phase-3-shared-extraction', model: 'haiku' },
+    { title: 'Recon', detail: '4 mappers: the four duplicated modules, post-Phase-2 bundling sites, test-loader plumbing, deployed-zip baseline (read-only AWS)' },
+    { title: 'Spec', detail: 'serial fable spec: pin shared-module contents, handler edit lists, web_ui staging, bundling strings, EMF design, test plumbing' },
+    { title: 'Implement', detail: 'opus: shared/ + four handlers; sonnet: both CDK stacks; opus: all test plumbing + README — disjoint files', model: 'opus' },
+    { title: 'Verify', detail: 'mechanical gates + bundle-parity verifier + 3 fable lenses (auth integrity, EMF/telemetry, loader integrity)' },
+    { title: 'Fix', detail: 'opus fixer, full re-verify, max 3 rounds', model: 'opus' },
+    { title: 'Package', detail: 'single commit via -F (no push)', model: 'sonnet' },
+  ],
+}
+
+// ---------------------------------------------------------------- constants
+
+const REPO = '/Users/adammoussa/Documents/repositories/seahaven/procurement-ingest'
+const BRANCH = 'feature/phase-3-shared-extraction'
+let _args = args
+if (typeof _args === 'string') {
+  try { _args = JSON.parse(_args) } catch (e) { _args = null }
+}
+const BASE = (_args && _args.base) || 'main'
+
+const CONSTRAINTS = `
+PINNED BEHAVIORAL CONSTRAINTS (docs/refactor-evaluation.md Phase 3 — violating any is a build failure):
+1. THE MOVE SET IS EXACTLY FOUR MODULES, in this order of dependency risk:
+   lambdas/shared/ses_auth.py, lambdas/shared/web_ui_auth.py,
+   lambdas/shared/email_parsing.py, lambdas/shared/emf.py. Nothing else
+   moves into shared/. lambdas/shared/ is the handbook location
+   (cdk-project-layout.md); modules land FLAT in every bundle so bare-name
+   imports keep working.
+2. ses_auth: FIRST verify the two current copies are still byte-identical
+   (sha256 both against the ${BASE} versions — any drift since the audit is
+   a blocker, not something to silently reconcile). shared/ses_auth.py is
+   the EXACT bytes of that single copy; both originals are git rm'd. The
+   email-processor handlers keep 'from ses_auth import
+   authenticate_inbound_email' UNCHANGED — flat landing in /asset-output
+   means ZERO handler diff for this move, which is what keeps fail-closed
+   auth byte-identical through the change.
+3. web_ui_auth: extract exactly the byte-identical block — _get_auth_token /
+   _header / is_authenticated + the four cache globals — from BOTH web_ui
+   handlers. The per-stack INFRA-74 comments STAY in each handler (their
+   wording has drifted deliberately; they are stack-specific — do NOT unify
+   or move them into the shared module). Fail-closed semantics (unset ARN,
+   Secrets Manager exception -> deny) must be unchanged; the token-cache
+   globals move with the functions that read them.
+4. email_parsing.py: parse_raw_email as the SUPERSET version returning cc
+   unconditionally. WO's output is bit-identical to today; PO simply
+   ignores cc — do NOT "clean up" PO to consume it, and do NOT preserve two
+   variants.
+5. emf.py: a generic emitter parameterized by namespace / dimension-sets /
+   properties. Every call site's emitted EMF envelope must be EXACTLY what
+   it emits today — the dimension-set list
+   [["ParseMethod"],["ParseMethod","TemplateId"]] is load-bearing for the
+   alarms and metric filters; making one-sided dimension fixes impossible
+   is the point of this move. Emission ORDERING is untouchable: PO emits
+   ai_fallback BEFORE the Bedrock call, WO after its gate with mutually-
+   exclusive ai_fallback/ai_fallback_rejected — these two deliberate
+   per-pipeline differences are pinned by tests; converting a call site
+   must not move it. The deliberate-double-count comments survive.
+6. DERIVED-FIELDS EXCEPTION: if recon finds _emit_derived_agreement_metric
+   lives INSIDE derived_fields.py, do NOT convert it — derived_fields.py
+   and the shadow DerivedFieldAgreement telemetry are UNTOUCHABLE while the
+   bake runs (this outranks the emf consolidation). Leave it as a third
+   copy with a code comment pointing at shared/emf.py and report it in
+   notes/blockers. Only convert it if it lives outside derived_fields.py.
+7. UNTOUCHABLE FILES (git diff ${BASE}...HEAD must be empty for each):
+   both template_parser.py (990 vs 508 lines, genuinely divergent — stays
+   per-pipeline), derived_fields.py, both validate_ai_fallback gate
+   modules, extract_with_claude's Bedrock invocation/prompt logic. Handler
+   diffs are LIMITED to: deleting moved code, import changes, and
+   emitter-call swaps per the binding spec. No opportunistic refactors.
+8. Bundling (cdk): append 'cp shared/*.py /asset-output/' to BOTH
+   email-processor bundling commands (Phase 2 made the bundling cwd the
+   ../lambdas asset root, so the path resolves as written).
+   BASE-AWARENESS — READ THE ACTUAL cdk FILES ON THE BASE, DO NOT ASSUME:
+   this phase is stacked on the Phase 7 branch, which ALREADY removed the
+   pip install step from both email-processor commands (they are now
+   CP-ONLY: no pip line, no manylinux pin, because nothing third-party is
+   installed). Phase 3 moves only pure first-party modules (no new deps),
+   so cp-only STAYS cp-only — you simply add another 'cp shared/*.py
+   /asset-output/' line. DO NOT re-introduce a pip install step and DO NOT
+   re-add the manylinux pin: there is nothing to pin when nothing installs,
+   and adding a pip step back would be the regression here. (The PR #34
+   lesson — never drop the manylinux pin while a pip install runs — still
+   holds ONLY if recon finds a pip step actually present on the base; on
+   the cp-only Phase 7 base there is none.) PRESERVE the Phase 2 exclude
+   lists exactly. Both web_ui functions gain the SAME staging mechanism
+   (widened-root bundled from_asset) so web_ui_auth.py ships beside their
+   handler — the spec agent pins the exact form. site_extractor's
+   from_asset is UNTOUCHED (Phase 6 territory).
+9. tests/test_bundle_consistency.py is updated IN THE SAME CHANGE without
+   losing teeth: the PO_EXPECTED_TOP_LEVEL_MODULES exact-set pin gains the
+   shared modules that now ship; the AST sibling-import check must resolve
+   imports whose source file now lives under shared/; the new shared cp
+   line gets its own revert/mutation detection (a commented-out
+   'cp shared/*.py' must fail the test).
+10. Test plumbing in the same PR: update _SIBLING_MODULES resolution and
+    _po_parser_support.py (~line 71 — verify the current line) so tests
+    load ses_auth/email_parsing/emf from shared/; retire or repoint the
+    fixture-hygiene test that polices the two ses_auth copies for
+    byte-identity (obsolete once there is one copy — do not leave it
+    failing); drop the ses_auth fixture params from test_ses_auth
+    (parameterizing over two identical copies is dead weight — halves the
+    run). The sys.modules save/restore dance SURVIVES for template_parser
+    (still a duplicated bare name) — do not delete it. Preserve the
+    load-bearing moto-before-handler import ordering.
+11. STALE-SHADOW HAZARD: after the move, no stale ses_auth.py / .pyc /
+    __pycache__ copy may remain anywhere it could shadow the shared copy —
+    in the repo (git rm, don't empty), in staged assets, or on any test
+    sys.path. Verify explicitly.
+12. cdk diff on BOTH stacks: the only resource deltas allowed are Code/
+    S3Key (asset) changes on the two email processors and the two web_ui
+    functions (+ CDK metadata). No logical-ID changes, no alarm, IAM,
+    table, env, runtime, or handler-property deltas of any kind.
+13. AWS access is READ-ONLY (get-function, downloading deployed zips via
+    presigned URLs). NEVER cdk deploy, never invoke, never mutate.
+`
+
+const PREAMBLE = `
+You are one of several agents building refactor Phase 3 in the git repo at
+${REPO} on branch ${BRANCH} (already checked out — do NOT switch branches,
+do NOT create branches, do NOT commit, NEVER push, do NOT run cdk deploy or
+touch AWS resources beyond read-only calls).
+Authoritative spec: docs/refactor-evaluation.md, section "Phase 3".
+Work ONLY in the files you are told you own; other agents are concurrently
+editing other files in this same working tree.
+${CONSTRAINTS}
+Your final message is consumed by an orchestrator script, not a human —
+return only the structured data requested.
+`
+
+// ------------------------------------------------------------------ schemas
+
+const RECON = {
+  type: 'object',
+  required: ['summary', 'facts'],
+  properties: {
+    summary: { type: 'string' },
+    facts: { type: 'array', items: { type: 'string' } },
+    blockers: { type: 'array', items: { type: 'string' } },
+  },
+}
+
+const SPEC = {
+  type: 'object',
+  required: ['sharedModules', 'handlerEdits', 'webUiStaging', 'bundlingEdits', 'emfDesign', 'testPlumbing', 'parityRules', 'notes'],
+  properties: {
+    sharedModules: { type: 'string', description: 'per shared module: exact provenance (which copy is the source, sha256), full contents decision (verbatim move vs superset vs parameterized), and the public surface each importer uses' },
+    handlerEdits: { type: 'string', description: 'per handler (po/wo email_processor, po/wo web_ui): the exact deletions, import lines, and emitter-call swaps — file:line, nothing else may change' },
+    webUiStaging: { type: 'string', description: 'the complete new from_asset blocks for both web_ui functions: asset path, command or cp form, exclude list — exact code' },
+    bundlingEdits: { type: 'string', description: 'the two email-processor bundling command strings with cp shared/*.py appended, verbatim, plus the expected top-level module set of each resulting bundle' },
+    emfDesign: { type: 'string', description: 'shared/emf.py signature + per-call-site mapping proving each emitted envelope (namespace, dimension-set list, properties) is byte-equivalent to today; the derived-agreement emitter decision per constraint 6' },
+    testPlumbing: { type: 'string', description: 'every test/support file change: loader resolution, _SIBLING_MODULES, fixture-hygiene retirement, test_ses_auth de-parameterization, test_bundle_consistency edits with their mutation-detection shapes' },
+    parityRules: { type: 'string', description: 'how Verify judges staged bundles vs the deployed-zip baseline: expected first-party set per function (= deployed set + the new shared modules), ses_auth byte-identity requirement, expected removals (none beyond moved-file provenance), web_ui bundle expectations' },
+    notes: { type: 'string' },
+  },
+}
+
+const IMPL = {
+  type: 'object',
+  required: ['filesChanged', 'summary', 'checksRun'],
+  properties: {
+    filesChanged: { type: 'array', items: { type: 'string' } },
+    summary: { type: 'string' },
+    checksRun: { type: 'string' },
+    blockers: { type: 'array', items: { type: 'string' } },
+  },
+}
+
+const CHECKS = {
+  type: 'object',
+  required: ['passed', 'details'],
+  properties: {
+    passed: { type: 'boolean' },
+    details: { type: 'string' },
+    scopeViolations: { type: 'array', items: { type: 'string' } },
+  },
+}
+
+const PARITY = {
+  type: 'object',
+  required: ['passed', 'poVerdict', 'woVerdict', 'webUiVerdict', 'details'],
+  properties: {
+    passed: { type: 'boolean' },
+    poVerdict: { type: 'string', description: 'PO email-processor staged vs deployed: module-set delta exactly as spec, ses_auth bytes identical — full evidence' },
+    woVerdict: { type: 'string', description: 'same for WO email-processor' },
+    webUiVerdict: { type: 'string', description: 'both web_ui staged bundles: own *.py + web_ui_auth.py present, nothing stray, hashes deterministic' },
+    details: { type: 'string' },
+  },
+}
+
+const FINDINGS = {
+  type: 'object',
+  required: ['findings'],
+  properties: {
+    findings: {
+      type: 'array',
+      items: {
+        type: 'object',
+        required: ['title', 'severity', 'confirmed', 'evidence', 'fix'],
+        properties: {
+          title: { type: 'string' },
+          severity: { enum: ['critical', 'high', 'medium', 'low'] },
+          confirmed: { type: 'boolean' },
+          evidence: { type: 'string' },
+          fix: { type: 'string' },
+        },
+      },
+    },
+  },
+}
+
+// ------------------------------------------------------------------- setup
+
+phase('Setup')
+const setup = await agent(`
+In ${REPO}:
+1. SEQUENCING GATE — Phases 0, 1 AND 2 must all be on ${BASE} (Phase 3
+   edits the same stack files as Phase 2 and depends on its widened
+   ../lambdas asset roots to make shared/ reachable). git fetch origin,
+   then pick the base ref: origin/${BASE} if that remote ref exists,
+   otherwise the local branch ${BASE} (a stacked local-only base is
+   expected and fine). Verify on the base ref:
+   (a) Phase 0: tests/test_bundle_consistency.py exists
+       (git show <baseref>:tests/test_bundle_consistency.py | head -3);
+   (b) Phase 1: validate_ai_fallback exists in the PO pipeline
+       (git grep validate_ai_fallback <baseref> -- lambdas/po);
+   (c) Phase 2: BOTH cdk/po_stack.py and cdk/wo_stack.py on the base ref
+       contain Code.from_asset("../lambdas") for the email processors
+       (git show <baseref>:cdk/po_stack.py | grep -n '\\.\\./lambdas', same
+       for wo_stack.py).
+   If any is missing, STOP with a blocker naming the unmet phase and do
+   nothing else.
+2. Verify clean working tree (untracked .coverage / .claude/ / the local
+   44 MB lambdas/po/email_processor/package/ dir are fine; any OTHER dirt =
+   blocker, never stash or discard).
+3. git checkout ${BASE}; then git pull --ff-only ONLY if the branch has an
+   upstream (a local-only base skips the pull — not a blocker); then
+   git checkout -b ${BRANCH}
+4. gh pr list --state open --json number,title,headRefName (overlap check).
+Return facts: HEAD sha, per-phase gate evidence, open PRs, blockers.
+`, { label: 'setup:branch', model: 'haiku', schema: RECON })
+
+if (!setup || (setup.blockers && setup.blockers.length)) {
+  return { aborted: 'setup blockers', blockers: setup ? setup.blockers : ['setup agent died'], facts: setup ? setup.facts : [] }
+}
+log(`Branch ${BRANCH} ready off ${BASE}. ${setup.summary}`)
+
+// ------------------------------------------------------------------- recon
+
+phase('Recon')
+const recon = await parallel([
+  () => agent(`${PREAMBLE}
+Read-only recon of the FOUR duplicated surfaces being extracted:
+1. ses_auth.py both copies — sha256 of each (MUST match; drift = blocker),
+   line count, the exact import line each email-processor handler uses,
+   any other importer (git grep 'import ses_auth\\|from ses_auth').
+2. web_ui auth block — in BOTH web_ui handlers quote with file:line the
+   exact boundaries of the byte-identical block (_get_auth_token, _header,
+   is_authenticated, the four cache globals), diff the two blocks to prove
+   byte-identity, quote each INFRA-74 comment verbatim (they differ —
+   that is expected), and note everything else in each handler that CALLS
+   the block.
+3. parse_raw_email both copies — where each lives (own sibling file vs
+   inside handler.py), the exact cc delta between them, every call site.
+4. The THREE EMF emitters — quote each verbatim with file:line (PO
+   ParseMethod emitter, WO ParseMethod emitter,
+   _emit_derived_agreement_metric), namespace + dimension-set list +
+   properties of each, and CRITICALLY: which FILE _emit_derived_agreement_metric
+   lives in (constraint 6 hinges on whether it is inside derived_fields.py).
+   Also pin current line numbers of PO's pre-Bedrock ai_fallback emit and
+   WO's post-gate emit.
+25-35 precise facts.`,
+    { label: 'recon:duplicated-modules', model: 'sonnet', phase: 'Recon', schema: RECON }),
+
+  () => agent(`${PREAMBLE}
+Read-only recon of the post-Phase-2 CDK bundling state: for ALL FIVE
+Code.from_asset sites in cdk/po_stack.py and cdk/wo_stack.py quote verbatim
+with current file:line — asset path, full bundling command (or plain form),
+exclude list. For the two web_ui functions additionally record: runtime,
+architecture, handler property, memory/timeout, whether any requirements.txt
+exists for them, and every function property that must NOT change when
+bundling is added. Confirm lambdas/shared/ does not exist yet and list
+anything at lambdas/ top level. 15-25 facts.`,
+    { label: 'recon:cdk-bundling', model: 'haiku', phase: 'Recon', schema: RECON }),
+
+  () => agent(`${PREAMBLE}
+Read-only recon of the test plumbing this phase must rewire:
+- tests/conftest.py importlib loader: how it resolves module paths, the
+  sys.modules save/restore, _SIBLING_MODULES (exact current contents).
+- _po_parser_support.py: the independent importlib reimplementation, the
+  load-bearing moto-before-handler import order (~lines 26-33), and what
+  is at line ~71 (the doc cites it — quote the current code).
+- _wo_parser_support.py bare sys.path 'import handler' strategy.
+- test_ses_auth.py at root: the fixture parameterization over both copies
+  (quote it), total line count, the fixture-hygiene test that polices
+  byte-identity between the two copies (name + assertion).
+- test_parse_raw_email.py: how it loads both handlers' parse_raw_email.
+- tests/test_bundle_consistency.py: every assertion that will fail red
+  against the Phase 3 shapes (shared cp line, PO_EXPECTED_TOP_LEVEL_MODULES,
+  AST sibling-import resolution for moved modules).
+20-30 facts.`,
+    { label: 'recon:test-plumbing', model: 'sonnet', phase: 'Recon', schema: RECON }),
+
+  () => agent(`${PREAMBLE}
+Read-only AWS recon (region us-east-1, READ-ONLY): for po-email-processor,
+workorder-email-processor, AND both web_ui functions (find their exact
+function names via the stacks/aws lambda list-functions) run aws lambda
+get-function; for the two email processors download each Code.Location
+presigned zip to a scratch dir and produce the COMPLETE file list
+(unzip -l) separated into (a) first-party top-level .py, (b) dependency
+dirs, (c) anything else; record every function's CodeSha256 and the
+sha256 of ses_auth.py inside each deployed zip (the byte-identity baseline
+the moved copy is judged against). For the web_ui functions the current
+zip file list is the baseline their new bundled asset must cover.
+Return the categorized lists as facts.`,
+    { label: 'recon:deployed-baseline', model: 'sonnet', phase: 'Recon', schema: RECON }),
+])
+
+const reconOk = recon.filter(Boolean)
+const pack = reconOk.map(r => `## ${r.summary}\n${r.facts.join('\n')}`).join('\n\n')
+const reconBlockers = reconOk.flatMap(r => r.blockers || [])
+  .filter(b => b && !/^\s*(none|n\/a)\b/i.test(b))
+log(`Recon complete: ${reconOk.length}/4 mappers, ${reconBlockers.length} blockers`)
+if (reconBlockers.length) {
+  return { aborted: 'recon blockers (likely copy drift — resolve before extracting)', blockers: reconBlockers, reconPack: pack }
+}
+
+// -------------------------------------------------------------------- spec
+
+phase('Spec')
+const spec = await agent(`${PREAMBLE}
+You are the SPEC agent — the single authority that pins every contested
+decision BEFORE parallel implementation (parallel leaves cannot see each
+other's choices). Using the recon pack below plus your own reads of the
+actual files, produce the binding implementation spec:
+- sharedModules: per constraint 1's four modules — provenance, contents
+  decision, public surface. ses_auth is a verbatim byte-move; web_ui_auth
+  is the exact block; email_parsing is the WO superset (cc unconditional);
+  emf is the parameterized emitter.
+- handlerEdits: for each of the four handlers, the exact minimal edit list
+  (constraint 7 — deletions, imports, emitter-call swaps ONLY). State
+  explicitly that the two email-processor ses_auth import lines are
+  UNCHANGED.
+- webUiStaging: complete replacement from_asset blocks for both web_ui
+  functions — widened root, cp command staging the function's own *.py
+  plus web_ui_auth.py (pin whether to cp shared/*.py or just
+  shared/web_ui_auth.py — pick ONE rule, state why), Phase-2-style
+  excludes. Mind bundling cwd semantics: the container mounts the asset
+  root (../lambdas) as the working dir. If a no-Docker staging form is
+  viable and simpler, you may pin that instead — but ONE mechanism for
+  both, exact code.
+- bundlingEdits: both email-processor command strings verbatim with
+  'cp shared/*.py /asset-output/' appended, plus the exact expected
+  top-level module set of each resulting bundle (this feeds
+  PO_EXPECTED_TOP_LEVEL_MODULES and the parity gate).
+- emfDesign: the shared emitter signature and a per-call-site table
+  proving envelope byte-equivalence; resolve the derived-agreement emitter
+  per constraint 6 based on where recon found it.
+- testPlumbing: every file, every edit — loader resolution for shared/,
+  _SIBLING_MODULES, _po_parser_support.py, _wo_parser_support.py if it
+  needs the shared path, fixture-hygiene retirement, test_ses_auth
+  de-parameterization, test_parse_raw_email (single implementation now —
+  what does it exercise?), test_bundle_consistency edits including the new
+  mutation shapes (commented-out shared cp must fail).
+- parityRules: exactly how Verify judges staged bundles vs recon's
+  deployed baseline — per-function expected first-party set (deployed set
+  minus nothing, plus the shared modules per your cp rule), ses_auth
+  sha256 must equal the deployed zips' copy, web_ui bundles must cover
+  their deployed file list plus web_ui_auth.py, nothing else may appear
+  or vanish.
+Recon pack:\n${pack}`,
+  { label: 'spec:pin-extraction', phase: 'Spec', schema: SPEC })
+
+if (!spec) return { aborted: 'spec agent died — rerun workflow', reconBlockers }
+const specBlock = `BINDING SPEC (from the spec agent — implement EXACTLY this):\n${JSON.stringify(spec, null, 2)}`
+log('Spec pinned: shared modules, handler edits, web_ui staging, bundling strings, EMF design, test plumbing')
+
+// --------------------------------------------------------------- implement
+
+phase('Implement')
+const impl = await parallel([
+  () => agent(`${PREAMBLE}
+YOU OWN: everything under lambdas/ EXCEPT the tests/ directories (another
+agent owns all test and support files). Do not touch cdk/ or README.
+Task: execute the four moves per spec.sharedModules + spec.handlerEdits +
+spec.emfDesign, in the spec's order:
+1. git mv (or create+git rm preserving exact bytes) ses_auth.py ->
+   lambdas/shared/ses_auth.py; delete both originals; prove sha256
+   equality in your summary. Handler import lines untouched.
+2. Create lambdas/shared/web_ui_auth.py from the byte-identical block;
+   replace the block in BOTH web_ui handlers with the import; keep each
+   INFRA-74 comment in place.
+3. Create lambdas/shared/email_parsing.py (superset); rewire both
+   email-processor call sites.
+4. Create lambdas/shared/emf.py; swap the emitter call sites per
+   spec.emfDesign — honoring constraint 6 (derived_fields.py stays
+   untouched if the third emitter lives there) and constraint 5 (emission
+   ordering does not move).
+Delete every now-empty moved-out file with git rm (constraint 11).
+Run before returning: ruff check lambdas && ruff format lambdas --check,
+plus an import smoke: python3 -c with sys.path prepended for
+lambdas/shared + each function dir, importing every touched module (tests
+are NOT yours to run — the plumbing agent lands them in parallel).
+${specBlock}`,
+    { label: 'impl:shared-lambdas', model: 'opus', phase: 'Implement', schema: IMPL }),
+
+  () => agent(`${PREAMBLE}
+YOU OWN: cdk/po_stack.py and cdk/wo_stack.py ONLY (and only the from_asset
+regions — alarms, IAM, tables, env are all off-limits).
+Task: apply spec.bundlingEdits (append the shared cp to both
+email-processor commands — the base is the Phase 7 CP-ONLY bundling, so
+just add another 'cp shared/*.py /asset-output/' line; DO NOT re-add a pip
+install step or a manylinux pin, there is nothing third-party to install
+(constraint 8); preserve the Phase 2 excludes verbatim) and
+spec.webUiStaging (both web_ui functions). Touch nothing else;
+site_extractor's from_asset stays byte-identical.
+Run before returning: ruff check cdk && cd cdk &&
+npx cdk synth po-ingest -q -o /tmp/phase3-synth &&
+npx cdk synth workorder-ingest -q -o /tmp/phase3-synth (artifact-id
+selectors, NOT stack_name). Docker bundling runs — confirm each staged
+email-processor asset contains the shared modules and each staged web_ui
+asset contains web_ui_auth.py; note asset hashes in your summary. If the
+lambdas/ moves have not landed yet the synth will fail on missing files —
+poll by re-running up to ~10 min before reporting a blocker.
+${specBlock}`,
+    { label: 'impl:cdk-stacks', model: 'sonnet', phase: 'Implement', schema: IMPL }),
+
+  () => agent(`${PREAMBLE}
+YOU OWN: all test and support files (tests/ at repo root including
+tests/test_bundle_consistency.py and tests/conftest.py,
+lambdas/po/email_processor/tests/, lambdas/wo/email_processor/tests/)
+and README.md ONLY.
+Task A: apply spec.testPlumbing in full — loader/_SIBLING_MODULES
+resolution for shared/, _po_parser_support.py edit (preserving the
+moto-before-handler ordering comment), fixture-hygiene retirement,
+test_ses_auth de-parameterization, test_parse_raw_email update,
+test_bundle_consistency updates WITHOUT losing teeth (constraint 9 — the
+new shared cp pin must reject a commented-out or narrowed variant; keep
+the existing mutation tests green).
+Task B: README — document lambdas/shared/ in the repo-layout section
+(which modules live there, the flat-landing import rule, the bundling cp
+that ships them), update the bundling/deploy-guards paragraphs for the
+shared cp + web_ui staging, and note that ses_auth is now single-sourced
+(one hardening fix lands once). Match existing README style.
+Run before returning: pytest -q --no-cov at repo root (must be green
+against the OTHER agents' edits — they land in parallel; poll by
+re-running up to ~10 min before reporting a blocker) and ruff check on
+every file you touched.
+${specBlock}`,
+    { label: 'impl:test-plumbing-readme', model: 'opus', phase: 'Implement', schema: IMPL }),
+])
+
+const implOk = impl.filter(Boolean)
+const implBlockers = implOk.flatMap(r => r.blockers || [])
+log(`Implement complete: ${implOk.length}/3 agents, blockers: ${implBlockers.length}`)
+
+// ---------------------------------------------------- verify + fix loop
+
+const EXPECTED_SCOPE = [
+  'lambdas/shared/',
+  'lambdas/po/email_processor/',
+  'lambdas/wo/email_processor/',
+  'lambdas/po/web_ui/',
+  'lambdas/wo/web_ui/',
+  'cdk/po_stack.py',
+  'cdk/wo_stack.py',
+  'tests/',
+  'README.md',
+]
+
+const mechanicalPrompt = `${PREAMBLE}
+Independent re-verification — trust nothing self-reported. Run ALL gates,
+quoting failures verbatim:
+1. pytest -q --no-cov (repo root, all three roots green)
+2. ruff check . && ruff format --check .
+3. cd cdk && npx cdk synth po-ingest -q && npx cdk synth workorder-ingest -q
+4. cd cdk && npx cdk diff po-ingest ; npx cdk diff workorder-ingest —
+   constraint 12: only the four functions' Code/S3Key (+ metadata) deltas.
+   Any alarm/IAM/env/runtime/handler-prop/logical-ID delta = FAIL. Paste
+   the diff summaries.
+5. UNTOUCHABLES (each must output NOTHING):
+   git diff ${BASE}...HEAD -- lambdas/po/email_processor/derived_fields.py
+   git diff ${BASE}...HEAD -- lambdas/po/email_processor/template_parser.py
+   git diff ${BASE}...HEAD -- lambdas/wo/email_processor/template_parser.py
+   plus both validate_ai_fallback gate modules (resolve their filenames
+   first) and lambdas/po/site_extractor/.
+6. BYTE-IDENTITY: sha256 of lambdas/shared/ses_auth.py equals sha256 of
+   git show ${BASE}:lambdas/po/email_processor/ses_auth.py (and the wo
+   copy). Both originals gone from the tree (git ls-files check) and no
+   stray ses_auth.py/__pycache__ anywhere under lambdas/ outside shared/
+   (constraint 11).
+7. ORDERING PINS: grep line numbers proving PO's ai_fallback emit still
+   precedes the Bedrock invoke and WO's emits are untouched relative to
+   ${BASE} (the wo handler diff must contain ONLY the spec's edit classes).
+8. INFRA-74: both web_ui handlers still contain their own INFRA-74
+   comment verbatim per ${BASE}.
+9. git status --porcelain scope check: every modified/added/deleted path
+   under ${EXPECTED_SCOPE.join(', ')} (untracked .coverage/.claude/
+   package/ tolerated).
+passed=true only if all green. YOU MAY NOT edit files.`
+
+const parityPrompt = `${PREAMBLE}
+You are the BUNDLE-PARITY verifier — the load-bearing gate of this phase.
+Everything is local synth + read-only AWS.
+1. cd cdk && npx cdk synth po-ingest -q -o /tmp/phase3-parity &&
+   npx cdk synth workorder-ingest -q -o /tmp/phase3-parity. Locate all
+   four staged assets (two email processors, two web_ui).
+2. Re-download both email-processor deployed zips fresh (aws lambda
+   get-function Code.Location, us-east-1) — do not trust a recon cache —
+   and fetch both web_ui functions' deployed file lists.
+3. Judge per spec.parityRules: per email processor, staged first-party
+   top-level .py set == deployed set PLUS exactly the shared modules the
+   spec's cp rule ships (list both sets; nothing else may appear or
+   vanish); sha256 of staged ses_auth.py == sha256 of the ses_auth.py
+   inside each deployed zip (fail-closed auth byte-identical through the
+   move); dependency packages compared by name, version drift noted not
+   failed. Per web_ui function: staged bundle covers the deployed file
+   list plus web_ui_auth.py, nothing stray (no tests/, no other
+   pipeline's sources, no .eml, no package/).
+4. DETERMINISM: synth po-ingest twice into fresh -o dirs — identical
+   asset hashes, including the NEW web_ui assets. Then drop a throwaway
+   __pycache__/junk.pyc under lambdas/shared/ (delete it afterwards),
+   re-synth, and confirm the excludes keep every hash unchanged.
+5. IMPORT-RESOLUTION sanity: inside each staged email-processor asset
+   dir run python3 -c "import handler" with that dir alone on sys.path
+   (env-var stubs as needed) — proves the flat landing satisfies every
+   import including 'from ses_auth import ...' with the moved copy.
+passed=true only if every check holds.`
+
+const lenses = [
+  { key: 'auth-integrity', prompt: `${PREAMBLE}
+ADVERSARIAL REVIEW — auth-integrity lens. Auth code moved; try to prove
+the move WEAKENED it. (1) ses_auth: byte-compare the shared copy against
+${BASE}'s copies yourself; then attack import resolution — in the BUNDLE
+and in TESTS, which ses_auth wins if anything shadows (stale .pyc, a
+same-named module on sys.path, the tests loader resolving the old path
+silently to a stub)? Could a test now pass against a MOCK of ses_auth
+where it previously exercised the real module? (2) web_ui_auth: diff the
+extracted block against both originals — any dropped line, changed
+global, or reordered check? Is the fail-closed path (unset ARN, Secrets
+exception, wrong token -> 401 before any table access) provably
+unchanged? Do the four cache globals still behave per-function (module
+now shared — could cross-importer state ever leak)? (3) The gate call
+sites: could any handler path now reach S3-fetch/Bedrock/save before
+authenticate_inbound_email or is_authenticated, where it could not
+before? confirmed=true only with a concrete exploit sketch or
+file:line proof.` },
+  { key: 'telemetry-emf', prompt: `${PREAMBLE}
+ADVERSARIAL REVIEW — EMF/telemetry lens. The alarms and metric filters
+consume exact EMF shapes; a silent envelope change breaks paging without
+failing any test. Read shared/emf.py + every converted call site
+(git diff ${BASE}) and the synthesized templates' metric filters/alarms.
+Verify per call site: namespace exact, dimension-set list EXACT
+([["ParseMethod"],["ParseMethod","TemplateId"]] where applicable, order
+included), property keys/types identical, timestamp/CloudWatchMetrics
+envelope structure identical — construct a sample emission per call site
+and diff it against ${BASE}'s hand-built _aws dict output. Then the
+ordering pins: PO ai_fallback still pre-Bedrock, WO still post-gate
+mutually-exclusive, the deliberate double-count comment intact. Finally
+constraint 6: where does _emit_derived_agreement_metric live and was the
+decision honored (derived_fields.py diff empty)? confirmed=true only
+with evidence.` },
+  { key: 'loader-integrity', prompt: `${PREAMBLE}
+ADVERSARIAL REVIEW — test/loader-integrity lens. The three loading idioms
+were rewired; attack them. (1) Does test_ses_auth now exercise the REAL
+lambdas/shared/ses_auth.py (trace the loader path), and did
+de-parameterization silently drop any assertion that only ran under one
+param? (2) Fixture-hygiene: the byte-identity police is retired — does
+anything still guard against a future stray ses_auth.py copy reappearing
+in a pipeline dir (should the bundle-consistency or a hygiene test)? If
+nothing does, that is a finding. (3) sys.modules save/restore: prove it
+still isolates template_parser between pipelines (run two cross-pipeline
+tests back to back); prove moto-before-handler ordering survived in
+_po_parser_support.py. (4) test_bundle_consistency: hand-mutate command
+strings on scratch copies — a commented-out 'cp shared/*.py', a shared
+glob narrowed to one file, and a PO_EXPECTED_TOP_LEVEL_MODULES missing a
+shared module must each FAIL. (5) Run pytest twice in one session and in
+file-shuffled order (-p no:randomly not installed? then two explicit
+orderings) to smoke out import-order coupling introduced by the shared
+path. confirmed=true only with file:line or reproduced-failure
+evidence.` },
+]
+
+let round = 0
+let checks = null
+let parity = null
+let confirmed = []
+while (round < 3) {
+  phase('Verify')
+  const results = await parallel([
+    () => agent(mechanicalPrompt, { label: `verify:mechanical-r${round}`, model: 'sonnet', phase: 'Verify', schema: CHECKS }),
+    () => agent(parityPrompt, { label: `verify:parity-r${round}`, model: 'opus', phase: 'Verify', schema: PARITY }),
+    ...lenses.map(l => () =>
+      agent(l.prompt, { label: `verify:${l.key}-r${round}`, phase: 'Verify', schema: FINDINGS })),
+  ])
+  checks = results[0]
+  parity = results[1]
+  confirmed = results.slice(2).filter(Boolean)
+    .flatMap(r => r.findings || [])
+    .filter(f => f.confirmed && f.severity !== 'low')
+  const green = checks && checks.passed && parity && parity.passed
+  log(`Verify round ${round}: mechanical ${checks && checks.passed ? 'GREEN' : 'RED'}, parity ${parity && parity.passed ? 'GREEN' : 'RED'}, confirmed findings: ${confirmed.length}`)
+  if (green && confirmed.length === 0) break
+
+  round += 1
+  if (round >= 3) break
+  phase('Fix')
+  await agent(`${PREAMBLE}
+You are the fix agent — you may edit files under: ${EXPECTED_SCOPE.join(', ')}.
+Fix EVERY item below minimally; the binding spec and 13 pinned constraints
+still hold (a finding that conflicts with a constraint is reported, not
+"fixed" — the constraint wins, esp. constraint 6's derived_fields
+untouchability and constraint 5's emission ordering). Re-run the specific
+failing gate/test per fix.
+MECHANICAL:\n${checks ? checks.details : '(agent died — rerun all gates)'}
+PARITY:\n${parity ? parity.details : '(agent died — rerun all)'}
+CONFIRMED FINDINGS:\n${JSON.stringify(confirmed, null, 2)}
+${specBlock}`,
+    { label: `fix:round-${round}`, model: 'opus', phase: 'Fix', schema: IMPL })
+}
+
+const verifyClean = checks && checks.passed && parity && parity.passed && confirmed.length === 0
+if (!verifyClean) {
+  return {
+    status: 'NEEDS ATTENTION — verify not clean after 3 rounds; branch left uncommitted',
+    branch: BRANCH,
+    mechanical: checks,
+    parity,
+    unresolvedFindings: confirmed,
+    implBlockers,
+    reconBlockers,
+    spec,
+  }
+}
+
+// ----------------------------------------------------------------- package
+
+phase('Package')
+const commit = await agent(`${PREAMBLE.replace('do NOT commit, ', '')}
+YOU are the commit agent:
+1. Read ~/Documents/repositories/seahaven/engineering-handbook/commit-messages.md
+   and follow it exactly.
+2. git add only paths under: ${EXPECTED_SCOPE.join(', ')} and
+   .claude/workflows/phase-3-shared-extraction.js. NOT .coverage, NOT
+   package/. Verify the staged set with git status — the deletions of the
+   moved originals MUST be staged too.
+3. ONE commit; write the message to /tmp/phase3-commit-msg.txt and use
+   git commit -F /tmp/phase3-commit-msg.txt (backticks in -m get eaten by
+   zsh). Suggested subject:
+   "feat: extract lambdas/shared/ — single-source ses_auth, web_ui auth, email parsing, EMF emitter (refactor phase 3)"
+   Body: the four moves with the byte-identity evidence one-liner for
+   ses_auth, the flat-landing import rule, the shared cp bundling change +
+   web_ui staging, the derived-agreement emitter decision (constraint 6),
+   and the test-plumbing summary. NO AI attribution / Co-Authored-By
+   lines.
+4. Do NOT push. Return commit sha + shortstat in summary.`,
+  { label: 'package:commit', model: 'sonnet', phase: 'Package', schema: IMPL })
+
+return {
+  status: 'BUILT — committed locally, NOT pushed',
+  branch: BRANCH,
+  base: BASE,
+  commit: commit ? commit.summary : 'commit agent died — commit manually',
+  spec: { sharedModules: spec.sharedModules, webUiStaging: spec.webUiStaging, emfDesign: spec.emfDesign, derivedAgreementNote: spec.notes },
+  parityEvidence: parity ? { po: parity.poVerdict, wo: parity.woVerdict, webUi: parity.webUiVerdict } : null,
+  implementation: implOk.map(r => r.summary),
+  filesChanged: implOk.flatMap(r => r.filesChanged),
+  verifyRounds: round + 1,
+  blockers: implBlockers.concat(reconBlockers),
+  outstandingGates: [
+    '/sh-security-review (MANDATORY before push — auth code moved: ses_auth + the web_ui auth gate are exactly the authentication surface; run on the committed diff, and re-run after any post-review fix to this code)',
+    'cross-family cross_review.py NOT mandatory (no IAM change; handler event/return contracts unchanged — internal module moves only). Opt-in if judgment says so',
+    'push + PR + gh pr checks green',
+    'deploy-then-merge: deploy from branch, smoke green, one real PO + WO email each, watch BOTH sender-auth-rejected alarms through live mail (the auth move must not change accept/reject behavior), verify web_ui login still works, THEN merge — and note the post-merge CI redeploy being a no-op (unchanged asset hashes) is itself a verification signal',
+  ],
+}

README.md

@@ -100,7 +100,7 @@ All Lambdas: Python 3.12, ARM64, 60-day log retention.
 
 ### Sender authentication (INFRA-107)
 
-The `From` header and any `Authentication-Results` header inside the raw MIME are attacker-forgeable, so neither is trusted. Instead, both email processors (`lambdas/*/email_processor/ses_auth.py`) authenticate the sender against the verdicts SES itself stamps at delivery time, failing closed:
+The `From` header and any `Authentication-Results` header inside the raw MIME are attacker-forgeable, so neither is trusted. Instead, both email processors authenticate the sender against the verdicts SES itself stamps at delivery time, failing closed. The authenticator is **single-sourced** at `lambdas/shared/ses_auth.py` (Phase 3) — previously duplicated byte-for-byte in each pipeline's `email_processor/` dir and kept in sync by a fixture-hygiene test; now one copy, so a future hardening fix to the fail-closed logic lands **once** instead of needing two identical edits. The CDK bundling `cp`s it flat beside each handler so the handlers' unchanged `from ses_auth import authenticate_inbound_email` still resolves at runtime (see [`lambdas/shared/`](#deploy-pipeline-guards-phase-0)). The gate:
 
 1. Take **only the topmost** `Authentication-Results` header (SES prepends its trace headers; any lower copies arrived inside the message and are ignored).
 2. Require its authserv-id to be `amazonses.com`.
@@ -189,6 +189,25 @@ This is cleanup, not a regression: none of those file classes are imported at ru
 
 `tests/test_bundle_consistency.py` guards all of the above with a pure-AST check (no synth, no boto3, no handler import): it parses each handler.py's top-level first-party sibling imports, extracts the bundling `command=[...]` string from the corresponding CDK stack file, and asserts every required sibling module is guaranteed to ship. It recognizes both the scoped glob (`cp po/email_processor/*.py` / `cp wo/email_processor/*.py`, with or without a path prefix) and a whole-dir recursive copy (`cp -r . /asset-output/`) as unconditionally-safe shapes, and falls back to literal filename matching for any other (allowlist-style) shape. It pins each stack's command to the scoped-glob form specifically — a future revert to a narrowed single-file copy, a commented-out glob, or a filename allowlist missing a sibling all fail CI loudly instead of silently shipping a broken bundle. Runs in the existing pytest step, before synth.
 
+### Phase 3: shared module extraction (`lambdas/shared/`)
+
+Four first-party modules that were previously duplicated per pipeline (or inlined in each handler) are now **single-sourced** under `lambdas/shared/`, following the handbook's `lambdas/shared/` convention:
+
+| Module | What it is | Imported by |
+|---|---|---|
+| `ses_auth.py` | fail-closed SES sender-authentication (INFRA-107) | both email processors |
+| `web_ui_auth.py` | fail-closed `X-Auth-Token` gate + token cache (INFRA-74) | both web_ui handlers |
+| `email_parsing.py` | `parse_raw_email` (the WO superset that returns `cc` unconditionally; PO simply ignores `cc`) | both email processors |
+| `emf.py` | generic CloudWatch EMF emitter (`emit_metric`, `emit_parse_outcome`) parameterized by namespace / dimension-sets / properties | both email processors (PO also uses `emit_metric` for `DerivedFieldAgreement`) |
+
+**Flat-landing import rule.** The shared dir has **no `__init__.py`** — the modules are consumed by bare name (`from ses_auth import ...`, `from emf import emit_parse_outcome`), exactly as when they were siblings. This works because the bundling `cp` lands them **flat in `/asset-output/`** beside `handler.py`, so at runtime each shared module sits on the function's own `sys.path` under its bare name — the handler import lines are unchanged, which is what keeps the byte-identical fail-closed `ses_auth` behavior through the move. The load-bearing `emf` dimension-set list `[["ParseMethod"], ["ParseMethod", "TemplateId"]]` is now pinned **once** in `emf.py` (one-sided dimension drift between the two pipelines becomes structurally impossible), while the deliberate per-pipeline **emission-ordering** differences stay in the handlers (PO emits `ai_fallback` *before* the Bedrock call with an intentional double-count; WO emits mutually-exclusive `ai_fallback`/`ai_fallback_rejected` after its gate).
+
+**Bundling — email processors.** Both email-processor commands append a second glob, `cp shared/*.py /asset-output/`, after their own `cp <pipeline>/email_processor/*.py`. This ships all four shared modules flat into each email-processor zip. `web_ui_auth.py` therefore rides along into both email-processor bundles even though the email handlers never import it — a harmless, deliberate consequence of the all-of-`shared/` glob (`PO_EXPECTED_TOP_LEVEL_MODULES` and the bundle-parity expectations account for it). The base is cp-only (Phase 7 removed the pip install / `manylinux` pin from both email-processor commands, and this phase moves only pure first-party modules with no new dependencies, so it **stays** cp-only — no pip step is reintroduced).
+
+**Bundling — web UIs.** Both `po-web-ui` and `workorder-web-ui` gain the same widened-root Docker bundling mechanism: their `Code.from_asset` root widens to `../lambdas` and their command copies the function's own dir contents plus **only** `shared/web_ui_auth.py` (`cp shared/web_ui_auth.py`, *not* `cp shared/*.py`) — the web UIs need only the auth module, and shipping the email-processor-only modules would break the "deployed set + `web_ui_auth`, nothing else" parity. The per-stack INFRA-74 comments stay in each handler (their wording is deliberately pipeline-specific and is not unified). `site_extractor`'s asset is untouched.
+
+`tests/test_bundle_consistency.py` is updated in lockstep without losing teeth: `_first_party_sibling_imports` resolves shared-sourced imports under `lambdas/shared/`; the command extractor selects the email-processor command now that each stack has two bundled functions; `_bundling_ships_all` accumulates shipped module stems across **both** globs; `PO_EXPECTED_TOP_LEVEL_MODULES` gains the four shared modules; and a new pin + mutation test require the `cp shared/*.py` line to be actually executed (a commented-out or removed shared `cp` fails CI).
+
 ## Security
 
 **Web UI auth (defense-in-depth).** The `po-web-ui` / `workorder-web-ui` handlers refuse unauthenticated requests even though their public Function URLs were removed (INFRA-74). Each requires a shared secret in the `X-Auth-Token` header (or `Authorization: Bearer <token>`), compared in constant time against the configured token. The handler **fails closed** if the token is unset or unreadable (denies all). The token lives in the Secrets Manager secret `procurement-ingest/web-ui-auth-token`; only its ARN is passed to the Lambda (`WEB_UI_AUTH_TOKEN_SECRET_ARN`), and the value is fetched at runtime — never embedded in the CloudFormation template or Lambda env vars. The fetched value is cached in the warm container with a short TTL (5 min) so a rotated secret propagates without waiting for the execution environment to recycle. This is a defense-in-depth floor for a detached URL, not primary auth.
@@ -325,23 +344,32 @@ cdk/
   po_stack.py          # Purchase order pipeline resources
   wo_stack.py          # Work order pipeline resources
 lambdas/               # Phase 2: shared Code.from_asset("../lambdas") bundling root for
-                        # BOTH po-email-processor and workorder-email-processor -- each
-                        # bundling command `cp`s only its own po/email_processor/*.py or
-                        # wo/email_processor/*.py subset out; site_extractor and both
-                        # web_ui assets keep their own narrower, non-bundled asset root
+                        # BOTH po-email-processor and workorder-email-processor (and, since
+                        # Phase 3, both web_ui functions) -- each email-processor command
+                        # `cp`s its own po/email_processor/*.py (or wo/...) subset PLUS
+                        # `cp shared/*.py`; each web_ui command `cp`s its own dir PLUS only
+                        # `shared/web_ui_auth.py`; site_extractor keeps its narrower, non-
+                        # bundled asset root
+  shared/              # Phase 3: single-sourced first-party modules, landed FLAT (no
+                        # __init__.py -- bare-name imports) into each bundle by the cp above
+    ses_auth.py          # fail-closed SES sender-auth (INFRA-107) -- one copy, one fix
+    web_ui_auth.py       # fail-closed X-Auth-Token gate + token cache (INFRA-74)
+    email_parsing.py     # parse_raw_email (WO superset; returns cc unconditionally)
+    emf.py               # generic CloudWatch EMF emitter (dimension-sets pinned once)
   po/                  # PO pipeline Lambdas
     email_processor/
       handler.py         # template-first + Bedrock fallback, EMF metric, merge writes, {"healthcheck": true} early-return
       template_parser.py # pure deterministic Coupa parser + fail-closed validation gate
+      derived_fields.py  # deterministic site_code/trade/fiscal_year classifier (untouched by Phase 3)
       tests/             # golden-file + validation-gate + fallback-dispatch + healthcheck tests + fixtures
     site_extractor/
-    web_ui/
+    web_ui/              # handler.py imports `from web_ui_auth import is_authenticated` (shared)
   wo/                  # WO pipeline Lambdas
     email_processor/
       handler.py         # template-first + Bedrock fallback, EMF metric, #23 comment_id, {"healthcheck": true} early-return
       template_parser.py # pure deterministic parser + fail-closed validation gate
       tests/             # golden-file + validation-gate + comment_id + fallback + healthcheck tests
-    web_ui/
+    web_ui/              # handler.py imports `from web_ui_auth import is_authenticated` (shared)
 scripts/
   reprocess.py
   backfill_sites.py
@@ -349,7 +377,7 @@ scripts/
 test_local.py          # Parse sample emails through Bedrock locally (no AWS mutation)
 tests/
   requirements.txt         # Test-only deps (moto)
-  conftest.py              # AWS env stubs + per-pipeline module loader
+  conftest.py              # AWS env stubs + module loader (per-pipeline siblings + shared/ fallback)
   test_pad_zip.py          # PO zip-code padding tests
   test_parse_raw_email.py  # MIME parsing tests (PO + WO handlers)
   test_po_merge.py         # PO merge-write semantics tests (#97)

cdk/po_stack.py

@@ -262,7 +262,13 @@ class PoIngestStack(Stack):
                         # pip step removed in Phase 7: requirements.txt is now
                         # empty (boto3 comes from the Lambda runtime), so nothing
                         # is installed and the manylinux pin has nothing to pin.
-                        "cp po/email_processor/*.py /asset-output/",
+                        # shared/*.py ships the four modules extracted to
+                        # lambdas/shared/ (Phase 3): ses_auth, web_ui_auth,
+                        # email_parsing, emf. Flat cp keeps the bare-name
+                        # imports (e.g. `from ses_auth import ...`) resolving
+                        # unchanged in /asset-output.
+                        "cp po/email_processor/*.py /asset-output/ && "
+                        "cp shared/*.py /asset-output/",
                     ],
                 ),
             ),
@@ -602,14 +608,32 @@ class PoIngestStack(Stack):
             architecture=lambda_.Architecture.ARM_64,
             handler="handler.handler",
             code=lambda_.Code.from_asset(
-                # requirements.txt is excluded from the bundle: it exists only
-                # as a Dependabot anchor (git-based scan sees it), never pip-
-                # installed (this is a plain non-bundled asset) and never needed
-                # at runtime (boto3 comes from the Lambda runtime). Excluding it
-                # keeps the deployed asset hash neutral vs base while the manifest
-                # still lands in git for Dependabot.
-                "../lambdas/po/web_ui",
+                "../lambdas",
                 exclude=["**/__pycache__/**", "requirements.txt"],
+                bundling=cdk.BundlingOptions(
+                    image=lambda_.Runtime.PYTHON_3_12.bundling_image,
+                    command=[
+                        "bash",
+                        "-c",
+                        # web_ui_auth.py is shared (lambdas/shared) and must land
+                        # FLAT beside handler.py so the bare
+                        # `from web_ui_auth import is_authenticated` resolves at
+                        # runtime. Only web_ui_auth is copied from shared/ -- the
+                        # other shared modules (ses_auth/email_parsing/emf) are
+                        # email-processor-only and must not bloat the web UI zip.
+                        # requirements.txt stays excluded (Dependabot anchor only,
+                        # never runtime): keeps the deployed file list = {handler,
+                        # web_ui_auth}. NOTE: the top-level `exclude=` on
+                        # from_asset only filters the asset-hash fingerprint, NOT
+                        # the directory Docker bundling actually mounts, so a
+                        # local __pycache__/requirements.txt on disk at synth
+                        # time WOULD otherwise leak into the bundled zip -- strip
+                        # them explicitly post-cp instead of relying on exclude.
+                        "cp -r po/web_ui/. /asset-output/ && "
+                        "cp shared/web_ui_auth.py /asset-output/ && "
+                        "rm -rf /asset-output/__pycache__ /asset-output/requirements.txt",
+                    ],
+                ),
             ),
             timeout=Duration.seconds(60),
             memory_size=256,

cdk/wo_stack.py

@@ -248,7 +248,13 @@ class WorkorderIngestStack(Stack):
                         # pip step removed in Phase 7: requirements.txt is now empty
                         # (boto3 comes from the Lambda runtime), so nothing is installed
                         # and the manylinux pin has nothing to pin. cp-only is safe.
-                        "cp wo/email_processor/*.py /asset-output/",
+                        # shared/*.py ships the four modules extracted to
+                        # lambdas/shared/ (Phase 3): ses_auth, web_ui_auth,
+                        # email_parsing, emf. Flat cp keeps the bare-name
+                        # imports (e.g. `from ses_auth import ...`) resolving
+                        # unchanged in /asset-output.
+                        "cp wo/email_processor/*.py /asset-output/ && "
+                        "cp shared/*.py /asset-output/",
                     ],
                 ),
             ),
@@ -548,7 +554,31 @@ class WorkorderIngestStack(Stack):
             architecture=lambda_.Architecture.ARM_64,
             handler="handler.handler",
             code=lambda_.Code.from_asset(
-                "../lambdas/wo/web_ui", exclude=["**/__pycache__/**"]
+                "../lambdas",
+                exclude=["**/__pycache__/**"],
+                bundling=cdk.BundlingOptions(
+                    image=lambda_.Runtime.PYTHON_3_12.bundling_image,
+                    command=[
+                        "bash",
+                        "-c",
+                        # web_ui_auth.py is shared (lambdas/shared) and must land
+                        # FLAT beside handler.py so
+                        # `from web_ui_auth import is_authenticated` resolves at
+                        # runtime. Only web_ui_auth is copied from shared/. WO
+                        # baseline keeps __init__.py and requirements.txt, so the
+                        # whole web_ui dir is copied; deployed file list becomes
+                        # {__init__, handler, requirements.txt, web_ui_auth}.
+                        # NOTE: the top-level `exclude=` on from_asset only
+                        # filters the asset-hash fingerprint, NOT the directory
+                        # Docker bundling actually mounts, so a local
+                        # __pycache__ on disk at synth time WOULD otherwise leak
+                        # into the bundled zip -- strip it explicitly post-cp
+                        # instead of relying on exclude.
+                        "cp -r wo/web_ui/. /asset-output/ && "
+                        "cp shared/web_ui_auth.py /asset-output/ && "
+                        "rm -rf /asset-output/__pycache__",
+                    ],
+                ),
             ),
             timeout=Duration.seconds(15),
             memory_size=128,

lambdas/po/email_processor/handler.py

@@ -7,17 +7,17 @@ back to Claude on Bedrock for structured extraction on a miss/invalid result,
 then writes the result to the purchase-orders DynamoDB table.
 """
 
-import email
 import json
 import logging
 import os
 import re
 from datetime import datetime, timezone
 from decimal import Decimal, InvalidOperation
-from email import policy
 
 import boto3
 from derived_fields import derive_all
+from email_parsing import parse_raw_email
+from emf import emit_metric, emit_parse_outcome
 from ses_auth import authenticate_inbound_email
 from template_parser import try_deterministic_parse, validate_ai_fallback
 
@@ -36,7 +36,6 @@ BEDROCK_MODEL_ID = os.environ.get(
 # CloudWatch EMF namespace/metric for the parse-outcome metric (the PO
 # fallback-rate alarm in cdk/po_stack.py reads the ["ParseMethod"] series).
 METRIC_NAMESPACE = "Seahaven/PoIngest"
-METRIC_NAME = "ParseOutcome"
 
 # Shadow telemetry for the Python-derived classifier bake. One EMF record per
 # derived field per email, emitted ONLY on the ai_fallback path (the template
@@ -249,36 +248,6 @@ The Coupa commodity/category field if present in the email (e.g., "Maintenance -
 """
 
 
-def parse_raw_email(raw_bytes: bytes) -> dict:
-    """Parse a raw MIME email into subject, sender, and body text."""
-    msg = email.message_from_bytes(raw_bytes, policy=policy.default)
-
-    subject = msg.get("Subject", "")
-    sender = msg.get("From", "")
-    to = msg.get("To", "")
-    date = msg.get("Date", "")
-
-    body = ""
-    if msg.is_multipart():
-        for part in msg.walk():
-            content_type = part.get_content_type()
-            if content_type == "text/plain":
-                body = part.get_content()
-                break
-            elif content_type == "text/html" and not body:
-                body = part.get_content()
-    else:
-        body = msg.get_content()
-
-    return {
-        "subject": subject,
-        "sender": sender,
-        "to": to,
-        "date": date,
-        "body": body,
-    }
-
-
 def extract_with_claude(email_data: dict) -> dict:
     """Send parsed email to Claude on Bedrock for structured extraction.
 
@@ -347,26 +316,9 @@ def _emit_parse_method_metric(method, template_id, reason_code, po_number):
     dashboards). CloudWatch materializes only the exact dimension sets listed
     here and does NOT auto-aggregate, so the alarm's single-dimension query
     would receive no data unless ["ParseMethod"] is emitted explicitly."""
-    emf = {
-        "_aws": {
-            # EMF requires Timestamp (epoch ms); without it CloudWatch may not
-            # extract the metric datapoint from the log event.
-            "Timestamp": int(datetime.now(timezone.utc).timestamp() * 1000),
-            "CloudWatchMetrics": [
-                {
-                    "Namespace": METRIC_NAMESPACE,
-                    "Dimensions": [["ParseMethod"], ["ParseMethod", "TemplateId"]],
-                    "Metrics": [{"Name": METRIC_NAME, "Unit": "Count"}],
-                }
-            ],
-        },
-        "ParseMethod": method,
-        "TemplateId": template_id or "unknown",
-        "ReasonCode": reason_code or "ok",
-        "po_number": po_number or "",
-        METRIC_NAME: 1,
-    }
-    print(json.dumps(emf))
+    emit_parse_outcome(
+        METRIC_NAMESPACE, method, template_id, reason_code, "po_number", po_number
+    )
 
 
 def _derived_agreement(llm_value, python_value) -> str | None:
@@ -403,29 +355,22 @@ def _emit_derived_agreement_metric(field, llm_value, python_value, po_number):
     agreement = _derived_agreement(llm_value, python_value)
     if agreement is None:
         return
-    emf = {
-        "_aws": {
-            "Timestamp": int(datetime.now(timezone.utc).timestamp() * 1000),
-            "CloudWatchMetrics": [
-                {
-                    "Namespace": METRIC_NAMESPACE,
-                    "Dimensions": [["Field", "Agreement"]],
-                    "Metrics": [{"Name": DERIVED_METRIC_NAME, "Unit": "Count"}],
-                }
-            ],
+    emit_metric(
+        METRIC_NAMESPACE,
+        DERIVED_METRIC_NAME,
+        [["Field", "Agreement"]],
+        {
+            "Field": field,
+            "Agreement": agreement,
+            "po_number": po_number or "",
+            # Length-clamped: Python values are regex/enum-bounded by construction,
+            # but the LLM value is schema-unvalidated model output -- a hallucinated
+            # free-text field must not land unbounded in a 2-month log line
+            # (sh-security-review PO-DC-02, confirmed low).
+            "PythonValue": "" if python_value is None else str(python_value)[:64],
+            "LlmValue": "" if llm_value is None else str(llm_value)[:64],
         },
-        "Field": field,
-        "Agreement": agreement,
-        "po_number": po_number or "",
-        # Length-clamped: Python values are regex/enum-bounded by construction,
-        # but the LLM value is schema-unvalidated model output -- a hallucinated
-        # free-text field must not land unbounded in a 2-month log line
-        # (sh-security-review PO-DC-02, confirmed low).
-        "PythonValue": "" if python_value is None else str(python_value)[:64],
-        "LlmValue": "" if llm_value is None else str(llm_value)[:64],
-        DERIVED_METRIC_NAME: 1,
-    }
-    print(json.dumps(emf))
+    )
 
 
 def pad_zip(zip_code: str | None) -> str | None:

lambdas/po/email_processor/tests/_po_parser_support.py

@@ -34,6 +34,9 @@ import moto  # noqa: F401
 
 _HERE = os.path.dirname(__file__)
 _MODULE_DIR = os.path.abspath(os.path.join(_HERE, ".."))
+# Phase 3 single-sourced ses_auth/email_parsing/emf under lambdas/shared/.
+# _HERE = lambdas/po/email_processor/tests -> ../../.. = lambdas.
+_SHARED_DIR = os.path.abspath(os.path.join(_HERE, "..", "..", "..", "shared"))
 
 # The handler creates boto3 clients at import time; give it a region and dummy
 # creds so import works offline/under CI.
@@ -59,6 +62,24 @@ def _load_module(filename, module_name):
     return module
 
 
+def _load_shared_module(filename, module_name):
+    """Load a Phase 3 shared sibling (ses_auth/email_parsing/emf) from
+    lambdas/shared/. Mirrors ``_load_module`` but resolves against
+    ``_SHARED_DIR`` -- the handler ``from email_parsing import ...`` /
+    ``from emf import ...`` / ``from ses_auth import ...`` bare imports must be
+    pre-bound in sys.modules because this support module does NOT put shared/
+    on sys.path."""
+    if module_name in sys.modules:
+        return sys.modules[module_name]
+    spec = importlib.util.spec_from_file_location(
+        module_name, os.path.join(_SHARED_DIR, filename)
+    )
+    module = importlib.util.module_from_spec(spec)
+    sys.modules[module_name] = module
+    spec.loader.exec_module(module)
+    return module
+
+
 def load_template_parser():
     return _load_module("template_parser.py", f"{_HANDLER_NAME}__template_parser")
 
@@ -68,10 +89,14 @@ def load_po_handler():
         return sys.modules[_HANDLER_NAME]
     siblings = {
         "template_parser": load_template_parser(),
-        "ses_auth": _load_module("ses_auth.py", f"{_HANDLER_NAME}__ses_auth"),
+        "ses_auth": _load_shared_module("ses_auth.py", f"{_HANDLER_NAME}__ses_auth"),
         "derived_fields": _load_module(
             "derived_fields.py", f"{_HANDLER_NAME}__derived_fields"
         ),
+        "email_parsing": _load_shared_module(
+            "email_parsing.py", f"{_HANDLER_NAME}__email_parsing"
+        ),
+        "emf": _load_shared_module("emf.py", f"{_HANDLER_NAME}__emf"),
     }
     saved = {name: sys.modules.get(name) for name in siblings}
     sys.modules.update(siblings)

lambdas/po/email_processor/tests/test_po_bedrock_fallback.py

@@ -633,10 +633,12 @@ def test_fixture_hygiene_ses_auth_and_scrub_markers():
     from _po_parser_support import (
         ADVERSARIAL_STEMS,
         AI_FALLBACK_STEMS,
-        _load_module,
+        _load_shared_module,
     )
 
-    ses_auth = _load_module("ses_auth.py", "po_email_processor_handler__ses_auth")
+    ses_auth = _load_shared_module(
+        "ses_auth.py", "po_email_processor_handler__ses_auth"
+    )
     coupa = (
         [("new-po", s) for s in NEW_PO_STEMS]
         + [("cancellation", s) for s in CANCELLATION_STEMS]

lambdas/po/web_ui/handler.py

@@ -5,15 +5,14 @@ Serves a simple HTML dashboard for viewing purchase orders.
 Accessed via Lambda Function URL.
 """
 
-import hmac
 import json
 import logging
 import os
-import time
 from decimal import Decimal
 from html import escape as esc
 
 import boto3
+from web_ui_auth import is_authenticated
 
 logger = logging.getLogger()
 logger.setLevel(logging.INFO)
@@ -30,73 +29,6 @@ PO_TABLE = os.environ.get("PO_TABLE", "purchase-orders")
 # Manager to keep it out of CloudFormation templates and Lambda env vars. If the
 # ARN is unset or the secret is missing, the handler fails closed and denies every
 # request.
-_WEB_UI_AUTH_TOKEN_SECRET_ARN = os.environ.get("WEB_UI_AUTH_TOKEN_SECRET_ARN")
-# Refresh the cached token this often so a rotated secret propagates without
-# waiting for the execution environment to recycle (emergency-rotation path).
-_AUTH_TOKEN_CACHE_TTL_SECONDS = 300
-_auth_token_cache = None
-_auth_token_cached_at = 0.0
-
-
-def _get_auth_token() -> str | None:
-    """Fetch the shared web UI auth token from Secrets Manager.
-
-    Cached in the warm container for a short TTL so we don't hit Secrets Manager
-    on every request, while still picking up a rotated secret within the TTL
-    rather than only when the execution environment recycles. Returns None when
-    not configured or unreadable (the caller then fails closed).
-    """
-    global _auth_token_cache, _auth_token_cached_at
-    now = time.monotonic()
-    if (
-        _auth_token_cache is not None
-        and now - _auth_token_cached_at < _AUTH_TOKEN_CACHE_TTL_SECONDS
-    ):
-        return _auth_token_cache
-    if not _WEB_UI_AUTH_TOKEN_SECRET_ARN:
-        return None
-    secrets = boto3.client("secretsmanager")
-    try:
-        secret = secrets.get_secret_value(SecretId=_WEB_UI_AUTH_TOKEN_SECRET_ARN)
-        _auth_token_cache = secret["SecretString"]
-        _auth_token_cached_at = now
-        return _auth_token_cache
-    except Exception:
-        # Fail closed (return None -> caller 401s) but surface the failure: a
-        # Secrets Manager permission/config error would otherwise make every
-        # request 401 with no operational signal. The secret value is never
-        # logged.
-        logger.exception(
-            "Failed to fetch web UI auth token from Secrets Manager; "
-            "denying request (failing closed)"
-        )
-        return None
-
-
-def _header(event: dict, name: str) -> str:
-    """Case-insensitive header lookup from a Lambda Function URL / APIGW event."""
-    headers = event.get("headers") or {}
-    name_lower = name.lower()
-    for key, value in headers.items():
-        if key.lower() == name_lower:
-            return value or ""
-    return ""
-
-
-def is_authenticated(event: dict) -> bool:
-    """Constant-time check of the request's shared secret against the configured
-    token. Fails closed when no token is configured."""
-    token = _get_auth_token()
-    if not token:
-        return False
-    presented = _header(event, "x-auth-token")
-    if not presented:
-        auth = _header(event, "authorization")
-        if auth.lower().startswith("bearer "):
-            presented = auth[7:].strip()
-    if not presented:
-        return False
-    return hmac.compare_digest(presented, token)
 
 
 def get_purchase_orders(limit=500):

lambdas/shared/email_parsing.py

@@ -0,0 +1,34 @@
+import email
+from email import policy
+
+
+def parse_raw_email(raw_bytes: bytes) -> dict:
+    """Parse a raw email into subject, sender, body text."""
+    msg = email.message_from_bytes(raw_bytes, policy=policy.default)
+
+    subject = msg.get("Subject", "")
+    sender = msg.get("From", "")
+    to = msg.get("To", "")
+    cc = msg.get("Cc", "")
+    date = msg.get("Date", "")
+
+    body = ""
+    if msg.is_multipart():
+        for part in msg.walk():
+            content_type = part.get_content_type()
+            if content_type == "text/plain":
+                body = part.get_content()
+                break
+            elif content_type == "text/html" and not body:
+                body = part.get_content()
+    else:
+        body = msg.get_content()
+
+    return {
+        "subject": subject,
+        "sender": sender,
+        "to": to,
+        "cc": cc,
+        "date": date,
+        "body": body,
+    }

lambdas/shared/emf.py

@@ -0,0 +1,82 @@
+"""Shared CloudWatch EMF emitter for the procurement-ingest pipelines.
+
+A single generic ``emit_metric`` builds the Embedded Metric Format envelope
+(``_aws`` block + promoted dimension properties + the metric-value key) and
+prints it to stdout, where the Lambda log subscription materializes the metric.
+Both the PO and WO email processors emit their parse-outcome metric through
+``emit_parse_outcome`` so the load-bearing dimension-set list
+``[["ParseMethod"], ["ParseMethod", "TemplateId"]]`` is pinned in exactly ONE
+place -- a one-sided dimension change to one pipeline is structurally
+impossible.
+
+Envelope byte-equivalence rests on CPython dict insertion order (preserved by
+json.dumps with default separators): ``{**properties, metric_name: value}``
+yields ``_aws`` first, then the caller's properties in order, then the metric
+value last -- matching every inline emitter this module replaced.
+"""
+
+import json
+from datetime import datetime, timezone
+
+PARSE_METRIC_NAME = "ParseOutcome"
+
+# Two dimension sets are published for every parse-outcome metric: ["ParseMethod"]
+# (aggregated across all template ids -- the series the fallback-rate alarms
+# query) AND ["ParseMethod", "TemplateId"] (per-template breakdown for Logs
+# Insights / dashboards). CloudWatch materializes only the exact dimension sets
+# listed here and does NOT auto-aggregate, so an alarm's single-dimension query
+# would receive no data unless ["ParseMethod"] is emitted explicitly. Pinned
+# ONCE here; both pipelines share it.
+_PARSE_DIMENSION_SETS = [["ParseMethod"], ["ParseMethod", "TemplateId"]]
+
+
+def emit_metric(
+    namespace, metric_name, dimension_sets, properties, *, value=1, unit="Count"
+):
+    """Print one CloudWatch EMF log line for ``metric_name`` in ``namespace``.
+
+    Zero-latency (no PutMetricData API call): the extraction path is async and
+    the role already has logs:PutLogEvents. ``properties`` are emitted in caller
+    order between the ``_aws`` block and the trailing metric-value key; the keys
+    named in ``dimension_sets`` are the promoted (dimensioned) fields, the rest
+    ride along as Logs-Insights-queryable properties.
+    """
+    emf = {
+        "_aws": {
+            # EMF requires Timestamp (epoch ms); without it CloudWatch may not
+            # extract the metric datapoint from the log event.
+            "Timestamp": int(datetime.now(timezone.utc).timestamp() * 1000),
+            "CloudWatchMetrics": [
+                {
+                    "Namespace": namespace,
+                    "Dimensions": dimension_sets,
+                    "Metrics": [{"Name": metric_name, "Unit": unit}],
+                }
+            ],
+        },
+        **properties,
+        metric_name: value,
+    }
+    print(json.dumps(emf))
+
+
+def emit_parse_outcome(namespace, method, template_id, reason_code, id_key, id_value):
+    """Emit one parse-outcome EMF line shared by both email processors.
+
+    ParseMethod/TemplateId are the only promoted (dimensioned) fields to keep
+    cardinality low; ReasonCode and the pipeline id (``id_key``: ``po_number``
+    or ``work_order_id``) ride along as Logs-Insights-queryable properties. See
+    ``_PARSE_DIMENSION_SETS`` for why both the single- and two-dimension sets
+    are published.
+    """
+    emit_metric(
+        namespace,
+        PARSE_METRIC_NAME,
+        _PARSE_DIMENSION_SETS,
+        {
+            "ParseMethod": method,
+            "TemplateId": template_id or "unknown",
+            "ReasonCode": reason_code or "ok",
+            id_key: id_value or "",
+        },
+    )

lambdas/shared/web_ui_auth.py

@@ -0,0 +1,77 @@
+import hmac
+import logging
+import os
+import time
+
+import boto3
+
+logger = logging.getLogger()
+
+
+_WEB_UI_AUTH_TOKEN_SECRET_ARN = os.environ.get("WEB_UI_AUTH_TOKEN_SECRET_ARN")
+# Refresh the cached token this often so a rotated secret propagates without
+# waiting for the execution environment to recycle (emergency-rotation path).
+_AUTH_TOKEN_CACHE_TTL_SECONDS = 300
+_auth_token_cache = None
+_auth_token_cached_at = 0.0
+
+
+def _get_auth_token() -> str | None:
+    """Fetch the shared web UI auth token from Secrets Manager.
+
+    Cached in the warm container for a short TTL so we don't hit Secrets Manager
+    on every request, while still picking up a rotated secret within the TTL
+    rather than only when the execution environment recycles. Returns None when
+    not configured or unreadable (the caller then fails closed).
+    """
+    global _auth_token_cache, _auth_token_cached_at
+    now = time.monotonic()
+    if (
+        _auth_token_cache is not None
+        and now - _auth_token_cached_at < _AUTH_TOKEN_CACHE_TTL_SECONDS
+    ):
+        return _auth_token_cache
+    if not _WEB_UI_AUTH_TOKEN_SECRET_ARN:
+        return None
+    secrets = boto3.client("secretsmanager")
+    try:
+        secret = secrets.get_secret_value(SecretId=_WEB_UI_AUTH_TOKEN_SECRET_ARN)
+        _auth_token_cache = secret["SecretString"]
+        _auth_token_cached_at = now
+        return _auth_token_cache
+    except Exception:
+        # Fail closed (return None -> caller 401s) but surface the failure: a
+        # Secrets Manager permission/config error would otherwise make every
+        # request 401 with no operational signal. The secret value is never
+        # logged.
+        logger.exception(
+            "Failed to fetch web UI auth token from Secrets Manager; "
+            "denying request (failing closed)"
+        )
+        return None
+
+
+def _header(event: dict, name: str) -> str:
+    """Case-insensitive header lookup from a Lambda Function URL / APIGW event."""
+    headers = event.get("headers") or {}
+    name_lower = name.lower()
+    for key, value in headers.items():
+        if key.lower() == name_lower:
+            return value or ""
+    return ""
+
+
+def is_authenticated(event: dict) -> bool:
+    """Constant-time check of the request's shared secret against the configured
+    token. Fails closed when no token is configured."""
+    token = _get_auth_token()
+    if not token:
+        return False
+    presented = _header(event, "x-auth-token")
+    if not presented:
+        auth = _header(event, "authorization")
+        if auth.lower().startswith("bearer "):
+            presented = auth[7:].strip()
+    if not presented:
+        return False
+    return hmac.compare_digest(presented, token)

lambdas/wo/email_processor/handler.py

@@ -6,19 +6,18 @@ Parses the raw email, sends it to Claude for structured extraction,
 then writes the result to DynamoDB.
 """
 
-import email
 import hashlib
 import json
 import logging
 import os
 import re
 from datetime import datetime, timezone
-from email import policy
 from email.utils import parsedate_to_datetime
 
 import boto3
+from email_parsing import parse_raw_email
+from emf import emit_parse_outcome
 from ses_auth import authenticate_inbound_email
-
 from template_parser import try_deterministic_parse, validate_ai_fallback
 
 logger = logging.getLogger()
@@ -36,7 +35,6 @@ BEDROCK_MODEL_ID = os.environ.get(
 
 # CloudWatch EMF namespace + metric for parse-outcome observability.
 METRIC_NAMESPACE = "Seahaven/WorkorderIngest"
-METRIC_NAME = "ParseOutcome"
 
 EXTRACTION_PROMPT = """\
 You are an email parser for a facilities maintenance work order system.
@@ -79,38 +77,6 @@ Rules:
 """
 
 
-def parse_raw_email(raw_bytes: bytes) -> dict:
-    """Parse a raw email into subject, sender, body text."""
-    msg = email.message_from_bytes(raw_bytes, policy=policy.default)
-
-    subject = msg.get("Subject", "")
-    sender = msg.get("From", "")
-    to = msg.get("To", "")
-    cc = msg.get("Cc", "")
-    date = msg.get("Date", "")
-
-    body = ""
-    if msg.is_multipart():
-        for part in msg.walk():
-            content_type = part.get_content_type()
-            if content_type == "text/plain":
-                body = part.get_content()
-                break
-            elif content_type == "text/html" and not body:
-                body = part.get_content()
-    else:
-        body = msg.get_content()
-
-    return {
-        "subject": subject,
-        "sender": sender,
-        "to": to,
-        "cc": cc,
-        "date": date,
-        "body": body,
-    }
-
-
 # An <email>/</email> (or whitespace-padded variant) appearing INSIDE the
 # untrusted email text could forge the data-block boundary, so any such
 # sequence is neutralized before wrapping. A single [\s/]* class (not two
@@ -185,26 +151,14 @@ def emit_parse_metric(method, template_id, reason_code, work_order_id):
     dashboards). CloudWatch materializes only the exact dimension sets listed
     here and does NOT auto-aggregate, so the alarm's single-dimension query
     would receive no data unless ["ParseMethod"] is emitted explicitly."""
-    emf = {
-        "_aws": {
-            # EMF requires Timestamp (epoch ms); without it CloudWatch may not
-            # extract the metric datapoint from the log event (advisory A2).
-            "Timestamp": int(datetime.now(timezone.utc).timestamp() * 1000),
-            "CloudWatchMetrics": [
-                {
-                    "Namespace": METRIC_NAMESPACE,
-                    "Dimensions": [["ParseMethod"], ["ParseMethod", "TemplateId"]],
-                    "Metrics": [{"Name": METRIC_NAME, "Unit": "Count"}],
-                }
-            ],
-        },
-        "ParseMethod": method,
-        "TemplateId": template_id or "unknown",
-        "ReasonCode": reason_code or "ok",
-        "work_order_id": work_order_id or "",
-        METRIC_NAME: 1,
-    }
-    print(json.dumps(emf))
+    emit_parse_outcome(
+        METRIC_NAMESPACE,
+        method,
+        template_id,
+        reason_code,
+        "work_order_id",
+        work_order_id,
+    )
 
 
 def save_work_order(parsed: dict, s3_key: str):

lambdas/wo/email_processor/ses_auth.py

@@ -1,452 +0,0 @@
-"""Fail-closed SES sender authentication (INFRA-107).
-
-SES Email Receiving *prepends* its own trace headers -- including an
-``Authentication-Results`` header whose authserv-id is ``amazonses.com`` --
-to the top of the raw MIME it writes to S3. Everything below those
-prepended headers (the From header, any additional Authentication-Results
-copies) is attacker-controlled, so ONLY the topmost Authentication-Results
-header is trusted, and only when its authserv-id is ``amazonses.com``.
-
-An email is accepted only when that header carries ``dkim=pass`` for a
-domain in the ``ALLOWED_DKIM_DOMAINS`` allowlist (a comma-separated Lambda
-environment variable set by the CDK stack). Every other outcome fails
-closed and the email is rejected:
-
-- ``ALLOWED_DKIM_DOMAINS`` unset or empty
-- no Authentication-Results header at all
-- topmost header unparseable or from an authserv-id other than SES
-- no ``dkim=pass`` clause
-- ``dkim=pass`` only for domains outside the allowlist
-
-Observed SES format (2026-07-15, both ingest buckets)::
-
-    Authentication-Results: amazonses.com;
-     spf=pass (spfCheck: ...) client-ip=...; envelope-from=...; helo=...;
-     dkim=pass header.i=@seahaven.com;
-     dmarc=none header.from=hxgnsmartcloud.com;
-
-Note SES reports the passing DKIM identity as ``header.i=@<domain>``
-(RFC 6376 AUID), not ``header.d=``; the parser accepts both, and treats
-``header.d`` (the plain signing domain) as authoritative over ``header.i``
-when both are present. The ``header.i`` domain is derived per RFC 6376 as
-the part after the AUID's *last* ``@`` -- a ``@`` inside a quoted
-local-part (e.g. ``i="@seahaven.com"@attacker.com``) is signer-controlled
-label text, never the identity domain, and yields the true signer
-(``attacker.com``).
-
-**Clause injection defence (INFRA-107 hardening).** SES echoes several
-attacker-controlled SMTP-session tokens into its own Authentication-Results
-value as their own semicolon-delimited property clauses -- notably
-``envelope-from=<MAIL FROM>``, ``helo=<HELO>`` and ``header.from=<From
-domain>``. An RFC 5321 quoted-local-part MAIL FROM may legally contain
-spaces and semicolons, e.g.::
-
-    MAIL FROM:<"x; dkim=pass header.i=@amazon.coupahost.com"@attacker.com>
-
-which SES renders verbatim as ``envelope-from="x; dkim=pass
-header.i=@amazon.coupahost.com"@attacker.com;``. A naive ``split(";")``
-would tear the quoted string apart and manufacture a synthetic
-``dkim=pass header.i=@amazon.coupahost.com`` clause out of attacker input.
-The parser therefore tokenises per RFC 8601 / RFC 5322 structure: CFWS
-comments ``(...)`` are stripped first, and the value is split into clauses
-only on semicolons that sit *outside* a quoted-string. A ``;`` inside a
-quoted ``pvalue`` stays part of that one property clause and can never be
-read as the start of a ``dkim=`` methodspec.
-"""
-
-import email.parser
-import email.policy
-import json
-import logging
-import os
-import re
-
-logger = logging.getLogger()
-
-ALLOWED_DKIM_DOMAINS_ENV = "ALLOWED_DKIM_DOMAINS"
-SES_AUTHSERV_ID = "amazonses.com"
-
-# One resinfo clause of an Authentication-Results value, e.g.
-# "dkim=pass header.i=@seahaven.com". The clause must START with the
-# method=result pair; header.d= / header.i= may appear anywhere after it.
-# The result token must be terminated by end-of-clause or whitespace so
-# "dkim=pass-anything" can never be read as "pass". (Comments are stripped
-# before matching, so the pre-strip "dkim=pass(comment)" form arrives here
-# as "dkim=pass ..." and still terminates on whitespace.)
-_DKIM_RESULT_RE = re.compile(r"^dkim\s*=\s*([a-z0-9]+)(?=$|\s)", re.IGNORECASE)
-
-
-def get_allowed_dkim_domains() -> frozenset:
-    """Read the DKIM-domain allowlist from the environment (may be empty)."""
-    raw = os.environ.get(ALLOWED_DKIM_DOMAINS_ENV, "")
-    return frozenset(
-        d.strip().lower().lstrip("@").rstrip(".") for d in raw.split(",") if d.strip()
-    )
-
-
-def _unfold(value: str) -> str:
-    """Collapse RFC 5322 folding whitespace into single spaces."""
-    return re.sub(r"[\r\n\t ]+", " ", value).strip()
-
-
-def _strip_comments(value: str) -> tuple:
-    """Remove RFC 5322 CFWS comments ``(...)`` from an unfolded header value.
-
-    Comments may nest and may contain quoted pairs (``\\)``). A ``(`` that
-    appears *inside* a quoted-string is literal text, not a comment start,
-    so quoted-strings (which carry attacker-controlled ``pvalue`` content
-    such as a quoted MAIL FROM local part) are passed through untouched.
-    Dropping comments first means comment-embedded ``header.i=`` / ``;``
-    fakes can never influence clause splitting or domain extraction.
-
-    Every removed comment is replaced by a single space so comments act as
-    folding whitespace (RFC 5322 CFWS semantics). A ``)`` that appears
-    outside any comment (depth 0) is an unmatched close and makes the value
-    not well-formed, closing the ``)(`` clause-injection gap.
-
-    CFWS also means a comment abutting a token *ends* that token:
-    ``header.d=seahaven.com(note)`` reads as domain ``seahaven.com``, where
-    the pre-CFWS gluing behaviour read ``seahaven.comnote`` (rejected).
-    This is deliberate -- ``header.d`` is written verbatim by SES from a
-    *verified* signature's ``d=`` tag, so a comment in that position is
-    never attacker-controlled.
-
-    Returns ``(stripped_text, well_formed)``. ``well_formed`` is False when
-    the value ends inside an unterminated comment or quoted-string, or when
-    an unmatched ``)`` appears at the top level. Callers reject on
-    ``not well_formed`` so a malformed header (which could otherwise be
-    mis-tokenised) fails closed rather than being partially parsed.
-    """
-    out = []
-    depth = 0  # comment nesting depth
-    in_quote = False  # inside a quoted-string (only tracked at depth 0)
-    extra_close = False  # SES-AR-01: ")" at depth 0 (no matching open)
-    i = 0
-    n = len(value)
-    while i < n:
-        c = value[i]
-        if depth > 0:
-            # Inside a comment: only quoted-pairs and nested parens matter.
-            if c == "\\":
-                i += 2
-                continue
-            if c == "(":
-                depth += 1
-            elif c == ")":
-                depth -= 1
-                if depth == 0:
-                    # SES-AR-02: comment acts as folding whitespace (RFC 5322).
-                    out.append(" ")
-            i += 1
-            continue
-        if in_quote:
-            out.append(c)
-            if c == "\\" and i + 1 < n:
-                out.append(value[i + 1])
-                i += 2
-                continue
-            if c == '"':
-                in_quote = False
-            i += 1
-            continue
-        # Normal context (outside any comment or quoted-string).
-        if c == "(":
-            depth += 1
-            i += 1
-            continue
-        if c == ")":
-            # SES-AR-01: ")" at depth 0 is an unmatched close -- refuse to
-            # tokenise rather than letting a ")(...)" pair manufacture a
-            # gap where attacker text leaks out at depth 0.
-            extra_close = True
-            i += 1
-            continue
-        if c == '"':
-            in_quote = True
-        out.append(c)
-        i += 1
-    well_formed = depth == 0 and not in_quote and not extra_close
-    return "".join(out), well_formed
-
-
-def _split_clauses(value: str) -> list:
-    """Split a comment-free header value into clauses on top-level ``;``.
-
-    A semicolon inside a quoted-string is preserved as part of the clause,
-    so an attacker-controlled quoted ``pvalue`` (e.g. a quoted MAIL FROM
-    echoed into ``envelope-from=``) cannot smuggle in a fake ``dkim=pass``
-    clause. Callers must run :func:`_strip_comments` first.
-    """
-    clauses = []
-    buf = []
-    in_quote = False
-    i = 0
-    n = len(value)
-    while i < n:
-        c = value[i]
-        if in_quote:
-            buf.append(c)
-            if c == "\\" and i + 1 < n:
-                buf.append(value[i + 1])
-                i += 2
-                continue
-            if c == '"':
-                in_quote = False
-            i += 1
-            continue
-        if c == '"':
-            in_quote = True
-            buf.append(c)
-            i += 1
-            continue
-        if c == ";":
-            clauses.append("".join(buf))
-            buf = []
-            i += 1
-            continue
-        buf.append(c)
-        i += 1
-    clauses.append("".join(buf))
-    return clauses
-
-
-def _split_properties(clause: str) -> list:
-    """Split a clause into whitespace-separated ``name=pvalue`` tokens.
-
-    Whitespace *inside* a quoted-string does not split, so an RFC 8601 pvalue
-    that embeds a quoted-string (e.g. a DKIM AUID with a quoted local-part that
-    legally contains spaces) survives as a single token. This is the same
-    quoted-string discipline :func:`_split_clauses` applies at the ``;`` level,
-    reused here at the token level so ``header.d=`` / ``header.i=`` extraction
-    is quoted-string-aware rather than a naive regex grab.
-    """
-    tokens = []
-    buf = []
-    in_quote = False
-    i = 0
-    n = len(clause)
-    while i < n:
-        c = clause[i]
-        if in_quote:
-            buf.append(c)
-            if c == "\\" and i + 1 < n:
-                buf.append(clause[i + 1])
-                i += 2
-                continue
-            if c == '"':
-                in_quote = False
-            i += 1
-            continue
-        if c == '"':
-            in_quote = True
-            buf.append(c)
-            i += 1
-            continue
-        if c.isspace():
-            if buf:
-                tokens.append("".join(buf))
-                buf = []
-            i += 1
-            continue
-        buf.append(c)
-        i += 1
-    if buf:
-        tokens.append("".join(buf))
-    return tokens
-
-
-def _auid_domain(pvalue: str) -> str:
-    """Domain of a DKIM AUID (``header.i``) per RFC 6376.
-
-    The identity domain is the part after the *last* ``@`` of the AUID -- but a
-    ``@`` inside a quoted local-part is NOT the identity separator. So
-    ``"@seahaven.com"@attacker.com`` yields ``attacker.com`` (the real signer),
-    not ``seahaven.com``: the ``@seahaven.com`` sits inside the quoted
-    local-part and is signer-controlled label text, never the domain. A bare
-    unquoted ``@seahaven.com`` still yields ``seahaven.com``. Returns "" when
-    there is no top-level ``@`` (no valid domain) or the domain looks malformed.
-    """
-    last_at = -1
-    in_quote = False
-    i = 0
-    n = len(pvalue)
-    while i < n:
-        c = pvalue[i]
-        if in_quote:
-            if c == "\\":
-                i += 2
-                continue
-            if c == '"':
-                in_quote = False
-            i += 1
-            continue
-        if c == '"':
-            in_quote = True
-        elif c == "@":
-            last_at = i
-        i += 1
-    if last_at < 0:
-        return ""
-    domain = pvalue[last_at + 1 :].lower().rstrip(".")
-    # A DKIM domain-name is a plain dot-atom; anything with a residual quote is
-    # malformed (or a smuggling attempt) and must not be trusted.
-    if not domain or '"' in domain:
-        return ""
-    return domain
-
-
-def _plain_domain(pvalue: str) -> str:
-    """Domain of ``header.d`` -- the DKIM signing domain, a plain dot-atom.
-
-    SES writes ``header.d`` verbatim from the signature's ``d=`` tag, which is
-    never a quoted-string. A residual quote means malformed/smuggled input and
-    fails closed.
-    """
-    domain = pvalue.lower().rstrip(".")
-    if not domain or '"' in domain:
-        return ""
-    return domain
-
-
-def _clause_signer_domain(clause: str) -> str:
-    """Authoritative DKIM signer domain of a ``dkim=pass`` clause, or "".
-
-    ``header.d`` (the signing domain) is authoritative and is preferred when
-    present; only when it is absent does this fall back to ``header.i`` and
-    derive the domain from the AUID's post-final-``@`` part. Both lookups run
-    over :func:`_split_properties` tokens, so a ``header.d=``/``header.i=``
-    literal smuggled *inside* another property's quoted pvalue is confined to
-    that one token and can never be read as a top-level property.
-    """
-    header_d = None
-    header_i = None
-    for token in _split_properties(clause):
-        name, sep, val = token.partition("=")
-        if not sep:
-            continue
-        key = name.strip().lower()
-        if key == "header.d" and header_d is None:
-            header_d = val
-        elif key == "header.i" and header_i is None:
-            header_i = val
-    if header_d is not None:
-        return _plain_domain(header_d)
-    if header_i is not None:
-        return _auid_domain(header_i)
-    return ""
-
-
-def parse_authentication_results(value: str) -> tuple:
-    """Parse one Authentication-Results header value.
-
-    Returns ``(authserv_id, passing_dkim_domains)`` where the domains are the
-    authoritative signer domains of every ``dkim=pass`` clause -- ``header.d``
-    when present, else the ``header.i`` AUID's post-final-``@`` domain (see
-    :func:`_clause_signer_domain`). Malformed input yields ``("", frozenset())``,
-    which callers treat as a rejection.
-
-    Tokenisation is comment- and quoted-string-aware (RFC 8601 / RFC 5322) at
-    the ``;`` (clause), whitespace (property) and ``@`` (AUID domain) levels, so
-    attacker-controlled tokens SES echoes into its header (envelope-from, helo,
-    header.from) cannot be split into a forged ``dkim=pass`` clause and a quoted
-    AUID local-part cannot masquerade as the identity domain.
-    """
-    text, well_formed = _strip_comments(_unfold(value))
-    if not well_formed:
-        # Unbalanced quotes/comments: refuse to guess how to tokenise it.
-        return "", frozenset()
-    clauses = [c.strip() for c in _split_clauses(text)]
-    if not clauses or not clauses[0]:
-        return "", frozenset()
-
-    # First clause is the authserv-id, optionally followed by a version
-    # token ("amazonses.com 1"); take only the first token.
-    authserv_id = clauses[0].split()[0].strip('"').lower()
-
-    passing = set()
-    for clause in clauses[1:]:
-        match = _DKIM_RESULT_RE.match(clause)
-        if not match or match.group(1).lower() != "pass":
-            continue
-        domain = _clause_signer_domain(clause)
-        if domain:
-            passing.add(domain)
-    return authserv_id, frozenset(passing)
-
-
-def evaluate_sender_authentication(raw_email: bytes, allowed_domains) -> tuple:
-    """Evaluate the SES-stamped verdicts in a raw MIME message.
-
-    Returns ``(accepted, reason, detail)``. Pure function of its inputs so
-    it can be unit-tested without touching the environment.
-    """
-    if not allowed_domains:
-        return False, "allowlist_not_configured", {}
-
-    try:
-        # compat32 keeps header values as raw strings (we unfold ourselves)
-        # and never raises on structurally odd headers; headersonly avoids
-        # parsing the body at all.
-        msg = email.parser.BytesParser(policy=email.policy.compat32).parsebytes(
-            raw_email, headersonly=True
-        )
-    except Exception:
-        return False, "unparseable_message", {}
-
-    ar_headers = msg.get_all("Authentication-Results") or []
-    if not ar_headers:
-        return False, "authentication_results_missing", {}
-
-    # SES prepends its trace headers, so index 0 is the SES-stamped copy.
-    # Any Authentication-Results header further down arrived inside the
-    # message (attacker-suppliable) and is deliberately ignored.
-    #
-    # The parse is wrapped so an unexpected parser exception fails CLOSED
-    # (rejected, structured reason) instead of propagating out of the handler
-    # into Lambda's async retries / DLQ on attacker-crafted input.
-    try:
-        authserv_id, passing = parse_authentication_results(str(ar_headers[0]))
-    except Exception:
-        return False, "authentication_results_unparseable", {}
-    detail = {
-        "authserv_id": authserv_id,
-        "passing_dkim_domains": sorted(passing),
-    }
-
-    if authserv_id != SES_AUTHSERV_ID:
-        return False, "untrusted_authserv_id", detail
-    if not passing:
-        return False, "no_passing_dkim_signature", detail
-
-    matched = passing & set(allowed_domains)
-    if not matched:
-        return False, "dkim_domain_not_allowlisted", detail
-
-    detail["matched_domains"] = sorted(matched)
-    return True, "authenticated", detail
-
-
-def authenticate_inbound_email(raw_email: bytes, s3_key: str) -> bool:
-    """Fail-closed gate used by the S3-triggered handlers.
-
-    On rejection: logs a structured warning with the reason and S3 key and
-    returns False. Callers skip the message and return normally, so
-    rejected mail never errors the invocation (no retries, no DLQ spam).
-    """
-    allowed = get_allowed_dkim_domains()
-    accepted, reason, detail = evaluate_sender_authentication(raw_email, allowed)
-    if accepted:
-        logger.info(json.dumps({"event": "sender_auth_ok", "s3_key": s3_key, **detail}))
-        return True
-    logger.warning(
-        json.dumps(
-            {
-                "event": "sender_auth_rejected",
-                "reason": reason,
-                "s3_key": s3_key,
-                "allowed_dkim_domains": sorted(allowed),
-                **detail,
-            }
-        )
-    )
-    return False

lambdas/wo/email_processor/tests/_wo_parser_support.py

@@ -16,6 +16,14 @@ _HERE = os.path.dirname(__file__)
 _MODULE_DIR = os.path.abspath(os.path.join(_HERE, ".."))
 if _MODULE_DIR not in sys.path:
     sys.path.insert(0, _MODULE_DIR)
+# Phase 3: handler.py now imports ses_auth/email_parsing/emf, single-sourced
+# under lambdas/shared/ (no longer in _MODULE_DIR). Put shared/ on sys.path so
+# the handler's bare `from email_parsing import ...` etc. resolve. These modules
+# are single-copy, so bare-name caching is correct for both pipelines -- no
+# collision guard needed (that only matters for the duplicated template_parser).
+_SHARED_DIR = os.path.abspath(os.path.join(_HERE, "..", "..", "..", "shared"))
+if _SHARED_DIR not in sys.path:
+    sys.path.insert(0, _SHARED_DIR)
 os.environ.setdefault("AWS_DEFAULT_REGION", "us-east-1")
 
 FIXTURES = os.path.join(_HERE, "fixtures")

lambdas/wo/web_ui/handler.py

@@ -5,14 +5,13 @@ Serves a simple HTML dashboard for viewing work orders and comments.
 Accessed via Lambda Function URL.
 """
 
-import hmac
 import json
 import logging
 import os
-import time
 from html import escape as esc
 
 import boto3
+from web_ui_auth import is_authenticated
 
 logger = logging.getLogger()
 logger.setLevel(logging.INFO)
@@ -29,73 +28,6 @@ COMMENTS_TABLE = os.environ.get("COMMENTS_TABLE", "WorkOrderComments")
 # fetched at runtime from Secrets Manager to keep it out of CloudFormation
 # templates and Lambda env vars. If the ARN is unset or the secret is missing, the
 # handler fails closed and denies every request.
-_WEB_UI_AUTH_TOKEN_SECRET_ARN = os.environ.get("WEB_UI_AUTH_TOKEN_SECRET_ARN")
-# Refresh the cached token this often so a rotated secret propagates without
-# waiting for the execution environment to recycle (emergency-rotation path).
-_AUTH_TOKEN_CACHE_TTL_SECONDS = 300
-_auth_token_cache = None
-_auth_token_cached_at = 0.0
-
-
-def _get_auth_token() -> str | None:
-    """Fetch the shared web UI auth token from Secrets Manager.
-
-    Cached in the warm container for a short TTL so we don't hit Secrets Manager
-    on every request, while still picking up a rotated secret within the TTL
-    rather than only when the execution environment recycles. Returns None when
-    not configured or unreadable (the caller then fails closed).
-    """
-    global _auth_token_cache, _auth_token_cached_at
-    now = time.monotonic()
-    if (
-        _auth_token_cache is not None
-        and now - _auth_token_cached_at < _AUTH_TOKEN_CACHE_TTL_SECONDS
-    ):
-        return _auth_token_cache
-    if not _WEB_UI_AUTH_TOKEN_SECRET_ARN:
-        return None
-    secrets = boto3.client("secretsmanager")
-    try:
-        secret = secrets.get_secret_value(SecretId=_WEB_UI_AUTH_TOKEN_SECRET_ARN)
-        _auth_token_cache = secret["SecretString"]
-        _auth_token_cached_at = now
-        return _auth_token_cache
-    except Exception:
-        # Fail closed (return None -> caller 401s) but surface the failure: a
-        # Secrets Manager permission/config error would otherwise make every
-        # request 401 with no operational signal. The secret value is never
-        # logged.
-        logger.exception(
-            "Failed to fetch web UI auth token from Secrets Manager; "
-            "denying request (failing closed)"
-        )
-        return None
-
-
-def _header(event: dict, name: str) -> str:
-    """Case-insensitive header lookup from a Lambda Function URL / APIGW event."""
-    headers = event.get("headers") or {}
-    name_lower = name.lower()
-    for key, value in headers.items():
-        if key.lower() == name_lower:
-            return value or ""
-    return ""
-
-
-def is_authenticated(event: dict) -> bool:
-    """Constant-time check of the request's shared secret against the configured
-    token. Fails closed when no token is configured."""
-    token = _get_auth_token()
-    if not token:
-        return False
-    presented = _header(event, "x-auth-token")
-    if not presented:
-        auth = _header(event, "authorization")
-        if auth.lower().startswith("bearer "):
-            presented = auth[7:].strip()
-    if not presented:
-        return False
-    return hmac.compare_digest(presented, token)
 
 
 def get_work_orders(limit=500):

tests/conftest.py

@@ -19,15 +19,25 @@ os.environ.setdefault("AWS_SECRET_ACCESS_KEY", "testing")
 os.environ.setdefault("AWS_SESSION_TOKEN", "testing")
 
 REPO_ROOT = Path(__file__).resolve().parents[1]
+_SHARED_DIR = REPO_ROOT / "lambdas" / "shared"
 
 
-# Sibling modules that exist per-pipeline and are imported by bare name from
-# the handlers (the Lambda runtime puts each function's own directory on
-# sys.path). Both pipelines duplicate these filenames, so the bare names MUST
-# be bound to the right pipeline's file around each handler exec -- relying on
-# sys.path ordering (or on whatever a previously collected suite left in
-# sys.modules) silently binds a handler to the OTHER pipeline's sibling.
-_SIBLING_MODULES = ("ses_auth", "template_parser", "derived_fields")
+# Sibling modules imported by bare name from the handlers (the Lambda runtime
+# puts each function's own directory on sys.path; the CDK bundling then cp's the
+# shared modules in flat beside handler.py so those bare imports resolve too).
+# template_parser/derived_fields are duplicated PER PIPELINE, so their bare
+# names MUST be bound to the right pipeline's file around each handler exec --
+# relying on sys.path ordering (or on whatever a previously collected suite left
+# in sys.modules) silently binds a handler to the OTHER pipeline's sibling.
+# ses_auth/email_parsing/emf are now single-sourced under lambdas/shared/ (Phase
+# 3); the loop below resolves them from there via a shared-dir fallback.
+_SIBLING_MODULES = (
+    "ses_auth",
+    "template_parser",
+    "derived_fields",
+    "email_parsing",
+    "emf",
+)
 
 
 def _load_module(path, module_name):
@@ -69,7 +79,14 @@ def load_handler(relative_path, module_name):
         return _load_module(path, module_name)
     saved = {}
     for sibling in _SIBLING_MODULES:
+        # Per-pipeline siblings (template_parser/derived_fields) resolve next to
+        # the handler; the shared, single-sourced siblings (ses_auth/
+        # email_parsing/emf) fall back to lambdas/shared/. No ambiguity: post
+        # Phase 3 the shared names exist ONLY under shared/, the per-pipeline
+        # names ONLY next to the handler.
         sibling_path = path.parent / f"{sibling}.py"
+        if not sibling_path.exists():
+            sibling_path = _SHARED_DIR / f"{sibling}.py"
         if not sibling_path.exists():
             continue
         saved[sibling] = sys.modules.get(sibling)
@@ -109,11 +126,12 @@ def email_handler(request):
     return request.getfixturevalue(request.param)
 
 
-@pytest.fixture(params=["wo", "po"])
-def ses_auth(request):
-    """The ses_auth module of each pipeline (duplicated file, kept in sync)."""
-    pipeline = request.param
-    return load_handler(
-        f"lambdas/{pipeline}/email_processor/ses_auth.py",
-        f"{pipeline}_ses_auth",
-    )
+@pytest.fixture
+def ses_auth():
+    """The single-sourced ses_auth module (lambdas/shared/, Phase 3).
+
+    Previously parameterized over the two per-pipeline copies to prove they
+    stayed byte-identical; now there is exactly one copy, so this loads it
+    once -- halving the test_ses_auth run.
+    """
+    return load_handler("lambdas/shared/ses_auth.py", "shared_ses_auth")

tests/test_bundle_consistency.py

@@ -23,16 +23,45 @@ PO_HANDLER = REPO_ROOT / "lambdas" / "po" / "email_processor" / "handler.py"
 WO_HANDLER = REPO_ROOT / "lambdas" / "wo" / "email_processor" / "handler.py"
 PO_STACK = REPO_ROOT / "cdk" / "po_stack.py"
 WO_STACK = REPO_ROOT / "cdk" / "wo_stack.py"
+# Phase 3: ses_auth/web_ui_auth/email_parsing/emf are single-sourced here and
+# shipped into the email-processor bundles via `cp shared/*.py`.
+SHARED_DIR = REPO_ROOT / "lambdas" / "shared"
 
-# The complete set of top-level modules the PO email_processor ships via the
-# non-recursive `cp ./*.py` glob. Pinned as an upper bound: a new top-level
-# .py in that dir must be added here deliberately, which is the moment to
-# decide whether it SHOULD ship (a real module) or must be excluded (a scratch
-# or secrets file that from_asset would otherwise stage into the bundle on a
-# local deploy). See test_po_bundle_ships_no_unexpected_top_level_modules.
-PO_EXPECTED_TOP_LEVEL_MODULES = frozenset(
-    {"handler", "ses_auth", "template_parser", "derived_fields"}
-)
+# The names Phase 3 single-sourced under lambdas/shared/. After the move NONE
+# of these may reappear as a top-level .py in either email-processor pipeline
+# dir: every handler loader resolves a pipeline-local copy FIRST
+# (tests/conftest.py load_handler checks path.parent before _SHARED_DIR;
+# lambdas/wo/email_processor/tests/_wo_parser_support.py inserts the pipeline
+# dir ahead of shared/ on sys.path), so a stray reappearance would silently
+# SHADOW the single shared source in every handler-loaded test while
+# test_ses_auth / test_parse_raw_email keep exercising shared/ -- divergence
+# undetected. This is exactly the future-drift invariant the retired
+# byte-identity ses_auth fixture used to guard; it is now enforced by policing
+# the pipeline dirs and shared/ SEPARATELY (never as a union, which would let
+# the same name already expected in shared/ mask a pipeline-dir stray) --
+# see test_no_shared_module_shadow_in_pipeline_dirs and the per-dir exact-set
+# pins below.
+SHARED_MODULES = frozenset({"ses_auth", "email_parsing", "emf", "web_ui_auth"})
+
+# Exact top-level .py stems each dir must hold. Pinned as exact sets (both
+# bounds): the bundling globs (`cp <pipeline>/email_processor/*.py` +
+# `cp shared/*.py`) ship every top-level .py in these dirs, and
+# `Code.from_asset` stages untracked files too (it does not honor .gitignore),
+# so a stray scratch/secrets .py -- or a shadow copy of a shared module -- would
+# silently ship into the production zip on a local deploy. Any new top-level
+# module must be added here deliberately, the moment to decide whether it SHOULD
+# ship (a real module) or must be excluded.
+PO_PIPELINE_MODULES = frozenset({"handler", "template_parser", "derived_fields"})
+WO_PIPELINE_MODULES = frozenset({"__init__", "handler", "template_parser"})
+
+# Full shipped set of each email-processor bundle (pipeline glob + shared glob).
+# Derived from the per-dir pins above so it stays consistent with them; policed
+# per-dir (NOT via this union) so a shared-name shadow in a pipeline dir cannot
+# be masked. web_ui_auth is a deliberate, harmless ride-along of the pinned
+# `cp shared/*.py` (constraint #8) -- never imported by the email handlers, but
+# it ships, so it is part of the shipped set.
+PO_EXPECTED_TOP_LEVEL_MODULES = PO_PIPELINE_MODULES | SHARED_MODULES
+WO_EXPECTED_TOP_LEVEL_MODULES = WO_PIPELINE_MODULES | SHARED_MODULES
 
 # Pipeline-scoped glob shapes the per-stack ships-all pins accept. Phase 2
 # widened the bundling cwd to the shared ../lambdas asset root, so the executed
@@ -47,6 +76,22 @@ PO_EXPECTED_TOP_LEVEL_MODULES = frozenset(
 PO_SCOPED_GLOB_RE = r"(?:^|\s)(?:\./|po/email_processor/)?\*\.py(?:\s|$)"
 WO_SCOPED_GLOB_RE = r"(?:^|\s)(?:\./|wo/email_processor/)?\*\.py(?:\s|$)"
 
+# Phase 3: both email-processor bundles gain a second glob copying the
+# single-sourced shared modules flat into the zip. This must be the EXECUTED
+# form (`_executed_cp_commands` strips comments), so a commented-out shared cp
+# cannot false-pass the pin.
+SHARED_CP_RE = r"(?:^|\s)shared/\*\.py(?:\s|$)"
+
+# Phase 3: each stack's web_ui function stages ONLY shared/web_ui_auth.py flat
+# beside its handler (NOT all of shared/ -- the email-only modules must not
+# bloat the web UI zip). The auth-gated web_ui handlers do a module-top-level
+# `from web_ui_auth import is_authenticated`, so dropping/commenting this cp
+# ImportErrors the Lambda at cold start with green CI -- the PR #105 ImportError
+# class the AST test exists to prevent, but for a surface (web_ui) the
+# email-processor selector deliberately excludes. Checked as the EXECUTED form
+# so a commented-out cp cannot false-pass.
+WEB_UI_AUTH_CP_RE = r"(?:^|\s)shared/web_ui_auth\.py(?:\s|$)"
+
 
 def _first_party_sibling_imports(handler_path: Path) -> set[str]:
     """Top-level module names handler.py imports that are first-party siblings.
@@ -67,7 +112,16 @@ def _first_party_sibling_imports(handler_path: Path) -> set[str]:
             if node.module:
                 names.add(node.module.split(".")[0])
     sibling_dir = handler_path.parent
-    return {name for name in names if (sibling_dir / f"{name}.py").exists()}
+    # A first-party sibling resolves either next to the handler (per-pipeline:
+    # template_parser/derived_fields) or under lambdas/shared/ (single-sourced:
+    # ses_auth/email_parsing/emf, Phase 3). Both must count, or the ships-all
+    # pin would silently drop the shared siblings (ses_auth was silently
+    # dropped, email_parsing/emf never seen, before this resolved shared/).
+    return {
+        name
+        for name in names
+        if (sibling_dir / f"{name}.py").exists() or (SHARED_DIR / f"{name}.py").exists()
+    }
 
 
 def _extract_bundling_command(stack_path: Path) -> str:
@@ -79,11 +133,13 @@ def _extract_bundling_command(stack_path: Path) -> str:
     lines, with `#` comments interspersed) is folded by the parser itself,
     so this returns the exact single command string CDK will hand to bash.
 
-    Each stack currently has exactly one bundled function; if a second one
-    is ever added, "the" bundling command becomes ambiguous and every
-    assertion in this file needs to pick its target explicitly — so demand
-    exactly one match rather than silently returning whichever ast.walk
-    happens to visit first.
+    Since Phase 3 each stack has TWO bundled functions -- the email processor
+    and the web_ui function (which now also stages a shared module). "The"
+    bundling command this test cares about is the EMAIL-processor one, so we
+    select the command whose text mentions ``email_processor`` (its first cp
+    is ``cp <pipeline>/email_processor/*.py``) and demand exactly one match --
+    the web_ui command (``cp -r <pipeline>/web_ui/.``) and site_extractor do
+    not match.
     """
     tree = ast.parse(stack_path.read_text())
     commands: list[str] = []
@@ -94,13 +150,47 @@ def _extract_bundling_command(stack_path: Path) -> str:
                 last = list_node.elts[-1]
                 if isinstance(last, ast.Constant) and isinstance(last.value, str):
                     commands.append(last.value)
-    if len(commands) != 1:
+    email_cmds = [c for c in commands if "email_processor" in c]
+    if len(email_cmds) != 1:
         raise AssertionError(
-            f"expected exactly one bundling command=[...] list in {stack_path}, "
-            f"found {len(commands)} — update this test to select the intended "
-            "bundling command explicitly"
+            f"expected exactly one email-processor bundling command=[...] list in "
+            f"{stack_path}, found {len(email_cmds)} (of {len(commands)} total "
+            "command lists) — update this test to select the intended bundling "
+            "command explicitly"
         )
-    return commands[0]
+    return email_cmds[0]
+
+
+def _extract_web_ui_command(stack_path: Path) -> str:
+    """Extract the web_ui function's bash -c bundling command string.
+
+    Mirrors _extract_bundling_command but selects the command whose text
+    mentions ``web_ui`` (its first cp is ``cp -r <pipeline>/web_ui/.``). The
+    email-processor command (``cp <pipeline>/email_processor/*.py``, plus
+    ``cp shared/*.py``) and site_extractor do not contain ``web_ui`` in the
+    folded command STRING (the explanatory ``# ... web_ui_auth ...`` comments
+    around the email command are Python comments, not string content, so they
+    are not part of the folded literal). Demands exactly one match so an
+    ambiguity surfaces loudly instead of silently checking the wrong command.
+    """
+    tree = ast.parse(stack_path.read_text())
+    commands: list[str] = []
+    for node in ast.walk(tree):
+        if isinstance(node, ast.keyword) and node.arg == "command":
+            list_node = node.value
+            if isinstance(list_node, ast.List) and list_node.elts:
+                last = list_node.elts[-1]
+                if isinstance(last, ast.Constant) and isinstance(last.value, str):
+                    commands.append(last.value)
+    web_ui_cmds = [c for c in commands if "web_ui" in c]
+    if len(web_ui_cmds) != 1:
+        raise AssertionError(
+            f"expected exactly one web_ui bundling command=[...] list in "
+            f"{stack_path}, found {len(web_ui_cmds)} (of {len(commands)} total "
+            "command lists) — update this test to select the intended bundling "
+            "command explicitly"
+        )
+    return web_ui_cmds[0]
 
 
 def _executed_cp_commands(command: str) -> list[str]:
@@ -127,39 +217,38 @@ def _bundling_ships_all(command: str, sibling_names: set[str]) -> bool:
     """True if `command` is guaranteed to ship every name in `sibling_names`.
 
     Inspects only the `cp` commands bash actually executes (comments stripped
-    via `_executed_cp_commands`). An executed copy ships every top-level .py
-    sibling unconditionally in two shapes:
-      - a non-recursive glob copy whose (optional) path prefix resolves, under
-        the ../lambdas bundling cwd, to a directory that ACTUALLY contains
-        every required sibling, e.g. `cp po/email_processor/*.py /asset-output/`
-        (PO, Phase 2). The directory is filesystem-checked, not merely
-        pattern-matched: a wrong-pipeline or arbitrary-directory glob
-        (`cp wo/email_processor/*.py` in po_stack, `cp venv/lib/*.py`) does NOT
-        qualify, because that directory does not hold every required sibling --
-        so it can never short-circuit to True while dropping a module;
+    via `_executed_cp_commands`) and ACCUMULATES the set of shipped module
+    stems across ALL of them -- because since Phase 3 the required siblings
+    ship via TWO globs, not one: `cp <pipeline>/email_processor/*.py` covers
+    the per-pipeline siblings and `cp shared/*.py` covers the single-sourced
+    ones (ses_auth/email_parsing/emf). A single-cp "one glob ships everything"
+    check would wrongly report False now that coverage is split.
+
+    Each executed cp contributes to the shipped set as follows:
+      - a non-recursive `*.py` glob ships every top-level .py in the globbed
+        directory -- but ONLY that directory. Its (optional) path prefix is
+        resolved against the ../lambdas asset root (the Phase 2 bundling cwd)
+        and every `.py` stem actually present there is added. A wrong-pipeline
+        or arbitrary-directory glob (`cp wo/email_processor/*.py` in po_stack,
+        `cp venv/lib/*.py`) therefore contributes only what that dir really
+        holds (or nothing, if it does not exist) and can never cover a sibling
+        that lives elsewhere;
       - a recursive copy of the WHOLE source dir, e.g. `cp -r . /asset-output/`
-        -- the source operand must be `.`/`./`, so a narrowed recursive
-        copy like `cp -r ./package /asset-output/` does NOT qualify.
-    Any other executed `cp` is treated as an explicit filename allowlist (the
-    legacy PO form) and is safe only if every required `<name>.py` literally
-    appears among the copied filenames -- the branch that must reject a
-    reverted allowlist missing a sibling.
+        (`.`/`./` source only), ships everything -> short-circuit True;
+      - any other executed `cp` is an explicit filename allowlist (the legacy
+        PO form): each copied `<name>.py` stem is added, so a reverted
+        allowlist missing a sibling leaves that sibling out of the set.
+    Returns True only if every required sibling ended up in the accumulated set.
     """
     cp_cmds = _executed_cp_commands(command)
     if not cp_cmds:
         return False
-    copied_files: set[str] = set()
+    shipped: set[str] = set()
     for cp in cp_cmds:
         glob_match = re.search(r"(?:^|\s)((?:[\w./-]+/)?)\*\.py(?:\s|$)", cp)
         if glob_match:
-            # A `*.py` glob ships every top-level .py in the globbed directory
-            # -- but ONLY that directory. Resolve its prefix against the
-            # ../lambdas asset root (the Phase 2 bundling cwd) and confirm it
-            # actually holds every required sibling, so a wrong-pipeline glob
-            # cannot pass the ships-all check on the mere presence of a `*.py`.
             glob_dir = (REPO_ROOT / "lambdas" / glob_match.group(1)).resolve()
-            if all((glob_dir / f"{name}.py").exists() for name in sibling_names):
-                return True
+            shipped.update(p.stem for p in glob_dir.glob("*.py"))
             continue
         if re.search(r"cp\s+-r\s+\.\/?\s+/asset-output", cp):
             return True
@@ -169,8 +258,8 @@ def _bundling_ships_all(command: str, sibling_names: set[str]) -> bool:
             r"cp\s+(?:-\S+\s+)*(.*?)\s*/asset-output/?\"?\s*$", cp.strip()
         )
         if match:
-            copied_files.update(match.group(1).split())
-    return all(f"{name}.py" in copied_files for name in sibling_names)
+            shipped.update(Path(f).stem for f in match.group(1).split())
+    return all(name in shipped for name in sibling_names)
 
 
 def test_po_bundling_ships_all_first_party_siblings():
@@ -194,6 +283,16 @@ def test_po_bundling_ships_all_first_party_siblings():
         "arbitrary-directory glob is rejected here on purpose. "
         f"Executed cp commands: {executed_cps}"
     )
+    # Phase 3: the shared siblings (ses_auth/email_parsing/emf) ship via a
+    # SECOND executed glob, `cp shared/*.py /asset-output/`. Require it to be
+    # actually executed (comment-stripped), so commenting it out fails here;
+    # combined with ships-all below (those siblings resolve only under shared/)
+    # a removed/commented shared cp fails BOTH assertions.
+    assert any(re.search(SHARED_CP_RE, cp) for cp in executed_cps), (
+        "cdk/po_stack.py email-processor bundling command must EXECUTE "
+        "'cp shared/*.py /asset-output/' so the single-sourced shared modules "
+        f"ship flat beside handler.py. Executed cp commands: {executed_cps}"
+    )
     assert _bundling_ships_all(command, siblings), (
         f"cdk/po_stack.py bundling command does not ship all of {sorted(siblings)}: "
         f"{command!r}"
@@ -221,36 +320,115 @@ def test_wo_bundling_ships_all_first_party_siblings():
         "wrong-pipeline or arbitrary-directory glob is rejected here on purpose. "
         f"Executed cp commands: {executed_cps}"
     )
+    # Phase 3: shared siblings ship via the second executed glob `cp shared/*.py`.
+    assert any(re.search(SHARED_CP_RE, cp) for cp in executed_cps), (
+        "cdk/wo_stack.py email-processor bundling command must EXECUTE "
+        "'cp shared/*.py /asset-output/' so the single-sourced shared modules "
+        f"ship flat beside handler.py. Executed cp commands: {executed_cps}"
+    )
     assert _bundling_ships_all(command, siblings), (
         f"cdk/wo_stack.py bundling command does not ship all of {sorted(siblings)}: "
         f"{command!r}"
     )
 
 
-def test_po_bundle_ships_no_unexpected_top_level_modules():
-    """Upper bound: the PO glob ships EXACTLY the expected top-level modules.
+def test_po_email_processor_dir_ships_no_unexpected_top_level_modules():
+    """Upper bound on the PO pipeline dir alone (NOT unioned with shared/).
 
     The sibling-import tests above prove the glob ships every module the
-    handler needs (shipped >= required). This proves the other direction
-    (shipped <= expected): because `cp ./*.py` copies every top-level .py in
-    the dir -- and `Code.from_asset` stages untracked files too (it does not
-    honor .gitignore) -- a stray scratch/secrets .py left in this dir would
-    silently ship into the production zip on a local deploy. Pinning the set
-    forces any new top-level module to be added to
-    PO_EXPECTED_TOP_LEVEL_MODULES deliberately, at which point the author
-    decides whether it should ship or be excluded from bundling.
+    handler needs (shipped >= required). This proves the other direction for
+    the pipeline dir (shipped <= expected): because `cp po/email_processor/*.py`
+    copies every top-level .py in that dir -- and `Code.from_asset` stages
+    untracked files too (it does not honor .gitignore) -- a stray scratch or
+    secrets .py, OR a shadow copy of a moved shared module, would silently ship
+    into the zip on a local deploy. Policing this dir SEPARATELY from shared/
+    (rather than as a union with it) is what makes a strayed-back ses_auth.py /
+    email_parsing.py / emf.py FAIL here instead of being masked by the same name
+    already being expected in shared/.
     """
     top_level = {p.stem for p in PO_HANDLER.parent.glob("*.py")}
-    assert top_level == set(PO_EXPECTED_TOP_LEVEL_MODULES), (
+    assert top_level == set(PO_PIPELINE_MODULES), (
         "unexpected top-level .py set in lambdas/po/email_processor -- the "
-        "'cp ./*.py' glob would ship exactly these into the Lambda zip. "
-        f"Found {sorted(top_level)}, expected "
-        f"{sorted(PO_EXPECTED_TOP_LEVEL_MODULES)}. If a new module is "
-        "intended, add it to PO_EXPECTED_TOP_LEVEL_MODULES; if it is a scratch "
-        "or secrets file, remove it (or exclude it from bundling) before deploy."
+        "'cp po/email_processor/*.py' glob would ship exactly these into the "
+        f"Lambda zip. Found {sorted(top_level)}, expected "
+        f"{sorted(PO_PIPELINE_MODULES)}. A moved shared module "
+        f"({sorted(SHARED_MODULES)}) reappearing here would SHADOW the single "
+        "shared source in every handler-loaded test -- remove it. If a new "
+        "per-pipeline module is intended, add it to PO_PIPELINE_MODULES."
     )
 
 
+def test_wo_email_processor_dir_ships_no_unexpected_top_level_modules():
+    """Upper bound on the WO pipeline dir alone (NOT unioned with shared/).
+
+    The WO equivalent of the PO exact-set pin -- previously MISSING entirely,
+    so a stray .py (or a shadow copy of a moved shared module) in
+    lambdas/wo/email_processor was policed by nothing. Same rationale as the PO
+    pin: `cp wo/email_processor/*.py` ships every top-level .py in this dir, and
+    a strayed-back ses_auth/email_parsing/emf would shadow the shared source in
+    the WO handler-loaded tests.
+    """
+    top_level = {p.stem for p in WO_HANDLER.parent.glob("*.py")}
+    assert top_level == set(WO_PIPELINE_MODULES), (
+        "unexpected top-level .py set in lambdas/wo/email_processor -- the "
+        "'cp wo/email_processor/*.py' glob would ship exactly these into the "
+        f"Lambda zip. Found {sorted(top_level)}, expected "
+        f"{sorted(WO_PIPELINE_MODULES)}. A moved shared module "
+        f"({sorted(SHARED_MODULES)}) reappearing here would SHADOW the single "
+        "shared source in every handler-loaded test -- remove it. If a new "
+        "per-pipeline module is intended, add it to WO_PIPELINE_MODULES."
+    )
+
+
+def test_shared_dir_ships_no_unexpected_top_level_modules():
+    """Upper bound on lambdas/shared/ alone (NOT unioned with a pipeline dir).
+
+    `cp shared/*.py` ships every top-level .py under lambdas/shared/ into BOTH
+    email-processor bundles, so a stray scratch/secrets .py here would leak into
+    both production zips. Pinned to exactly the four single-sourced modules.
+    """
+    top_level = {p.stem for p in SHARED_DIR.glob("*.py")}
+    assert top_level == set(SHARED_MODULES), (
+        "unexpected top-level .py set in lambdas/shared -- the 'cp shared/*.py' "
+        "glob would ship exactly these into BOTH email-processor Lambda zips. "
+        f"Found {sorted(top_level)}, expected {sorted(SHARED_MODULES)}. If a new "
+        "shared module is intended, add it to SHARED_MODULES; if it is a scratch "
+        "or secrets file, remove it before deploy."
+    )
+
+
+def test_no_shared_module_shadow_in_pipeline_dirs():
+    """The moved shared names must live ONLY under lambdas/shared/.
+
+    Replaces the future-drift guard the retired byte-identity ses_auth fixture
+    used to provide. A stray reappearance of a moved shared module in either
+    email-processor pipeline dir would be resolved FIRST by every handler loader
+    -- tests/conftest.py load_handler checks `path.parent / f"{sibling}.py"`
+    before the _SHARED_DIR fallback, and
+    lambdas/wo/email_processor/tests/_wo_parser_support.py inserts the pipeline
+    dir ahead of shared/ on sys.path -- silently SHADOWING the single shared
+    source in every handler-loaded test, while test_ses_auth / test_parse_raw_email
+    keep exercising shared/. Divergence would go undetected. Police the pipeline
+    dirs and shared/ SEPARATELY so no union can mask the shadow.
+    """
+    for name in sorted(SHARED_MODULES):
+        assert (SHARED_DIR / f"{name}.py").exists(), (
+            f"{name}.py must exist under lambdas/shared/ (single source of truth)"
+        )
+        assert not (PO_HANDLER.parent / f"{name}.py").exists(), (
+            f"{name}.py reappeared in lambdas/po/email_processor -- it would "
+            "SHADOW lambdas/shared/{name}.py in every PO handler-loaded test "
+            "(the loader resolves the pipeline-local copy first). Delete it; "
+            "the single source lives under lambdas/shared/."
+        )
+        assert not (WO_HANDLER.parent / f"{name}.py").exists(), (
+            f"{name}.py reappeared in lambdas/wo/email_processor -- it would "
+            "SHADOW lambdas/shared/{name}.py in every WO handler-loaded test "
+            "(_wo_parser_support inserts the pipeline dir ahead of shared/ on "
+            "sys.path). Delete it; the single source lives under lambdas/shared/."
+        )
+
+
 def test_detection_logic_catches_allowlist_missing_a_sibling():
     """Unit-level check on `_bundling_ships_all` itself.
 
@@ -272,13 +450,15 @@ def test_detection_logic_catches_allowlist_missing_a_sibling():
 
     assert not _bundling_ships_all(reverted_allowlist_command, siblings)
 
-    # Control: the same allowlist shape WITH derived_fields.py added back in
-    # is correctly recognized as complete, proving the failure above is
-    # about the missing file and not a false-positive-prone regex.
+    # Control: the same allowlist shape listing ALL required siblings (including
+    # the Phase 3 shared ones -- derived_fields, email_parsing, emf added back)
+    # is correctly recognized as complete under the accumulate model, proving
+    # the failure above is about the missing files and not a regex artifact.
     complete_allowlist_command = (
         "pip install --platform manylinux2014_aarch64 --only-binary=:all: "
         "-r requirements.txt -t /asset-output && "
-        "cp handler.py ses_auth.py template_parser.py derived_fields.py /asset-output/"
+        "cp handler.py ses_auth.py template_parser.py derived_fields.py "
+        "email_parsing.py emf.py /asset-output/"
     )
     assert _bundling_ships_all(complete_allowlist_command, siblings)
 
@@ -325,6 +505,26 @@ def test_detection_logic_rejects_commented_out_scoped_glob():
     assert not _bundling_ships_all(commented_out_command, siblings)
 
 
+def test_detection_logic_rejects_commented_out_shared_cp():
+    """A `cp shared/*.py` surviving only in a `#` comment must not count as run.
+
+    Simulates a half-finished revert that drops the executed shared cp but
+    leaves its text trailing as a comment. `_executed_cp_commands` strips `#`
+    comments before any regex sees the segment, so the shared-cp text alone --
+    never executed by bash -- is not among the executed cp's. Combined with the
+    fixed ships-all (ses_auth/email_parsing/emf resolve ONLY under shared/), a
+    removed or commented shared cp fails both the SHARED_CP_RE pin and ships-all.
+    """
+    commented_out_command = (
+        "cp po/email_processor/*.py /asset-output/  # cp shared/*.py /asset-output/"
+    )
+    executed = _executed_cp_commands(commented_out_command)
+    assert not any(re.search(SHARED_CP_RE, cp) for cp in executed)
+    # And ships-all is False: the shared siblings never got shipped.
+    po_siblings = _first_party_sibling_imports(PO_HANDLER)
+    assert not _bundling_ships_all(commented_out_command, po_siblings)
+
+
 def test_detection_logic_rejects_wrong_pipeline_glob():
     """A glob pointing at the WRONG pipeline (or any other dir) must not pass.
 
@@ -361,3 +561,58 @@ def test_detection_logic_rejects_wrong_pipeline_glob():
     assert not re.search(PO_SCOPED_GLOB_RE, "cp wo/email_processor/*.py /asset-output/")
     assert re.search(WO_SCOPED_GLOB_RE, "cp wo/email_processor/*.py /asset-output/")
     assert not re.search(WO_SCOPED_GLOB_RE, "cp po/email_processor/*.py /asset-output/")
+
+
+def test_po_web_ui_bundle_stages_shared_auth_module():
+    """The PO web_ui bundle must EXECUTE `cp shared/web_ui_auth.py`.
+
+    Phase 3 removed the inline auth block from lambdas/po/web_ui/handler.py,
+    which now does a module-top-level `from web_ui_auth import is_authenticated`;
+    web_ui_auth.py lives ONLY under lambdas/shared/. No test imports the web_ui
+    handler, and the email-processor AST pins deliberately exclude the web_ui
+    command -- so without this pin, dropping/commenting the web_ui cp would
+    ImportError the auth-gated Lambda at cold start with green CI. Checked
+    against the comment-stripped executed cp so the old text surviving only in a
+    comment cannot satisfy it.
+    """
+    command = _extract_web_ui_command(PO_STACK)
+    executed_cps = _executed_cp_commands(command)
+    assert any(re.search(WEB_UI_AUTH_CP_RE, cp) for cp in executed_cps), (
+        "cdk/po_stack.py web_ui bundling command must EXECUTE "
+        "'cp shared/web_ui_auth.py /asset-output/' so the shared auth module "
+        "ships flat beside handler.py and `from web_ui_auth import "
+        f"is_authenticated` resolves at cold start. Executed cp commands: "
+        f"{executed_cps}"
+    )
+
+
+def test_wo_web_ui_bundle_stages_shared_auth_module():
+    """The WO web_ui bundle must EXECUTE `cp shared/web_ui_auth.py`.
+
+    WO equivalent of test_po_web_ui_bundle_stages_shared_auth_module -- same
+    ImportError-at-cold-start hazard for lambdas/wo/web_ui/handler.py.
+    """
+    command = _extract_web_ui_command(WO_STACK)
+    executed_cps = _executed_cp_commands(command)
+    assert any(re.search(WEB_UI_AUTH_CP_RE, cp) for cp in executed_cps), (
+        "cdk/wo_stack.py web_ui bundling command must EXECUTE "
+        "'cp shared/web_ui_auth.py /asset-output/' so the shared auth module "
+        "ships flat beside handler.py and `from web_ui_auth import "
+        f"is_authenticated` resolves at cold start. Executed cp commands: "
+        f"{executed_cps}"
+    )
+
+
+def test_detection_logic_rejects_commented_out_web_ui_auth_cp():
+    """A `cp shared/web_ui_auth.py` surviving only in a `#` comment must not pass.
+
+    Mirror of test_detection_logic_rejects_commented_out_shared_cp for the
+    web_ui staging: a half-finished revert that drops the executed cp but leaves
+    its text trailing as a comment must NOT register as executed, since bash
+    would never run it.
+    """
+    commented_out_command = (
+        "cp -r po/web_ui/. /asset-output/  # cp shared/web_ui_auth.py /asset-output/"
+    )
+    executed = _executed_cp_commands(commented_out_command)
+    assert not any(re.search(WEB_UI_AUTH_CP_RE, cp) for cp in executed)