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Author SHA1 Message Date
Adam Moussa
8d52cfadef
feat: Python derived-field classifier with shadow telemetry (PO PR 2) (#106)
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* feat: Python derived-field classifier with shadow telemetry for PO ingest

Port the site_code/trade/fiscal_year rules from EXTRACTION_PROMPT into a
pure, total derived_fields module applied in the shared enrich_parsed()
post-stage. Python fills gaps on both parse paths (the template path has
no LLM values, closing the derived-field gap opened by the PR #105
two-PR split) and never overwrites a non-null LLM value; on ai_fallback
a DerivedFieldAgreement EMF record per field shadows Python against the
LLM during the bake. Rules hardened against a full-corpus backtest
(3,422 real emails vs the LLM-written baseline): site_code 99.4% with
zero Python-wrong cases, fiscal_year 100%, trade 96.8% ex-deliberate.
Also: quantity/price now declared numeric in the prompt, and
derived_fields.py added to the po_stack bundling copy (deploy-time
ImportError otherwise).

* fix: security-review hardening — EMF value length clamp, aggregate trade CPU budget

sh-security-review (4 detectors + proof-or-kill verifier): PASS, 0
confirmed critical/high. Fixes the one confirmed low (unbounded
LLM-value str() into the DerivedFieldAgreement EMF log line, clamped to
64 chars) and adds the verifier-recommended defense-in-depth aggregate
character budget across line items in derive_trade (per-item caps alone
allowed ~10s full-core on a pathological direct-call input; unreachable
through the deployed handler but cheap to bound). Bundling cp list now
carries a warning comment (GPT-4.1 cross-review FIX).
2026-07-17 11:47:33 -04:00
Adam Moussa
dc17de4026
feat: template-first PO parser with fail-closed gate and Bedrock fallback (#105)
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* Add deterministic template parser for WO emails

The workorder-email-processor sends every one of ~22.9k emails/month to
an LLM, but ~93.6% are the plain-text "AMAZON UPDATE WO DETAILS" comment
template and ~6.4% the HTML "AMAZON assign Work Order" template. Parse
those two shapes deterministically, offline, so the AI call is reserved
for the long tail.

The module is pure (no boto3, no network). try_deterministic_parse
classifies by subject, extracts the shared contract fields, and returns
a result ONLY when it passes a strict fail-closed validation gate: exact
contract-key set, subject/id agreement, the literal "Work Order:  <id>"
double space, per-type required fields, site-code shape, and a
label-bleed guard so a value that over-ran into the next field fails.
Any miss, drift, or extractor exception yields None so the caller falls
back to the AI extractor -- data is never corrupted, only the fallback
rate rises.

Refs: #23

* Migrate WO processor to Bedrock and fix comment_id collision

Switch the AI path from the Anthropic SDK to bedrock-runtime InvokeModel
on the inference profile us.anthropic.claude-haiku-4-5-20251001-v1:0
(BEDROCK_MODEL_ID env), so parsing no longer needs a provider API key or
Secrets Manager secret. The EXTRACTION_PROMPT and JSON contract are kept
byte-identical, so the AI-fallback output is unchanged. Try the new
deterministic template parser first and only call Bedrock on a
miss/invalid result.

Fix issue #23: the WorkOrderComments range key was
work_order_id#<comment_time>, so two emails on one WO with an identical
or absent comment time collided and overwrote each other. Derive a
12-hex suffix from the S3 object key alone -- deterministic, so an async
retry of the same object is byte-identical (idempotent) while distinct
emails get distinct keys -- and keep wall-clock now() out of the key
(literal 'nocomment' segment when comment_time is absent).

Also emit one CloudWatch EMF line per record (Seahaven/WorkorderIngest
ParseOutcome, dimensioned by ParseMethod/TemplateId) for parse-outcome
observability, replace the deprecated datetime.utcnow() with
datetime.now(timezone.utc), and drop the anthropic dependency.

Refs: #23

* Migrate PO processor to Bedrock

Switch the PO email processor's AI extraction from the Anthropic SDK to
bedrock-runtime InvokeModel on the inference profile
us.anthropic.claude-haiku-4-5-20251001-v1:0 (BEDROCK_MODEL_ID env), so
it no longer needs a provider API key or Secrets Manager secret. PO
parsing stays fully AI -- only the provider changes. The EXTRACTION_PROMPT
is kept byte-identical and the Bedrock text output is still decoded with
json.loads(..., parse_float=Decimal), which DynamoDB requires (it rejects
floats). Replace the deprecated datetime.utcnow() with
datetime.now(timezone.utc) and drop the anthropic dependency.

* Grant Bedrock IAM, drop Anthropic secrets, add fallback alarm

Both stacks moved their processors from the Anthropic API to the Bedrock
inference profile us.anthropic.claude-haiku-4-5-20251001-v1:0. Grant each
processor role bedrock:InvokeModel + bedrock:InvokeModelWithResponseStream
on BOTH the inference-profile ARN AND the per-region foundation-model
ARNs for us-east-1/us-east-2/us-west-2 (empty-account) -- the us.* profile
routes cross-region, so a profile-only grant AccessDenies at runtime.

Remove both anthropic-api-key Secret constructs, their grant_read, and
the ANTHROPIC_API_KEY_SECRET_ARN env; add BEDROCK_MODEL_ID. The secrets
had RemovalPolicy.RETAIN so they are orphaned, not deleted -- flagged in
the README for manual post-deploy deletion and key revocation.

Add the workorder-email-processor-template-fallback-rate alarm: a
FILL(0) + >=10-sample volume-floor MathExpression over the EMF
ParseOutcome metric (15-min periods) that pages when the AI-fallback
share exceeds 15% sustained, catching Hexagon template drift. ALARM-only
SnsAction to site-alerts, no OK action, NOT_BREACHING, matching the
existing stack idiom.

* Add offline WO parser test suite

Cover the deterministic parser with golden-file tests over 55 real
scrubbed .eml fixtures (both comment sub-shapes, username Submitted-By,
address present/absent, br+CRLF assign addresses), fail-closed
validation-gate rules, adversarial and prompt-injection cases that must
route to ai_fallback or parse without corrupting other fields, the issue
#23 comment_id idempotency invariants, and the Bedrock-fallback dispatch
plus EMF-metric emission with a mocked invoke_model.

Extend pytest.ini testpaths to discover the co-located suite, and update
tests/conftest.load_handler to put a handler's own directory on sys.path
so the WO handler's new `from template_parser import ...` resolves under
the existing shared handler tests. Point test_local.py at the new
template-first + Bedrock flow.

Refs: #23

* Document Bedrock migration and WO parse flow in README

Record the provider switch to the Bedrock inference profile (no Anthropic
API key or Secrets Manager secret, with the retired secrets flagged for
manual deletion), the WO deterministic-template-first + AI-fallback flow,
the new ParseOutcome EMF metric and template-fallback-rate alarm, the
issue #23 comment_id format change, the +00:00 aware-UTC timestamp shift,
and offline test instructions.

Refs: #23

* Fix f-string lint and formatting in backfill scripts

Drop the f prefix from two f-strings that carry no placeholders
(F541) and apply ruff format, so `ruff check` / `ruff format --check`
pass in CI.

* Emit ParseMethod-only EMF set so fallback alarm can fire

The fallback-rate alarm queries the ParseOutcome series keyed on
ParseMethod alone, but the emitter published only the joint
(ParseMethod, TemplateId) dimension set. CloudWatch materializes
exactly the listed dimension sets and does not auto-aggregate, so the
alarm's series never received data: it evaluated a constant 0 and
could never page on template-drift coverage collapse.

Publish both ["ParseMethod"] and ["ParseMethod","TemplateId"] and
update the EMF regression test to assert both sets are present.

* Commit WO parser .eml fixtures for executable coverage

The parser test suite globbed for input .eml fixtures that the repo's
`*.eml` ignore rule kept uncommitted, so every parametrized golden and
fail-closed test collected zero cases and CI could not exercise the
deterministic parser that handles 100% of WO email volume.

Add a fixtures-only negation to .gitignore and commit the 55 scrubbed
positive samples (50 update-plaintext, 5 assign-html) plus 14
ai-fallback and 3 adversarial fixtures. The ai-fallback set covers each
fail-closed reason code (subject_no_match, single_space_work_order,
malformed_site_code, label_bleed, creation_time_unparseable,
wo_id_mismatch, missing_required_field) and the adversarial set proves
the parser is total and confines prompt-injection payloads to
comment_text without steering the structured fields.

* feature: Add PO template parser scaffold and design doc

Mirror WO PR #99's template-first approach for the Coupa PO processor. Two templates identified from a full 3,448-email triage:
- coupa_new_po (95.5%): scaffolded; fails closed to the LLM until extract_new_po lands.
- coupa_cancellation (2.9%): implemented.

Nested contract with recursive validation, Decimal money, and a fail-closed gate. Derived fields (site_code/trade/fiscal_year) are deferred to a shared post-stage. Comments, revisions, multi-line, and non-USD emails fall back to Bedrock. docs/po-template-parser.md records the investigation, decisions, and remaining work.

Signed-off-by: Adam Moussa <166072409+amoussa1229@users.noreply.github.com>

* Implement PO new_po extraction and value-level gate

Replace the extract_new_po scaffold stub with the full
section-windowed extractor (duplicate-label anchoring, sentinel
ship-to, label-keyed U+2022 bullet split, Decimal money from three
anchored contexts only) and add value-level gate rules V1-V13.
Both new_po_not_implemented scaffold guards are removed; rules 6-8
(unrecognized_status, multiline_unsupported, non_usd) go live.

The gate re-derives every byte proof from the email body so an
extractor bug cannot vouch for itself: amount re-serialization
with a digit/comma border check (the thousands-separator
truncation kill switch), sum(lines)==total against both Total
blocks, anchor/supplier identity proofs, USPS address shape on
the raw pre-enrichment zip, bullet label discipline, and
sentinel/artifact hygiene. Any failure falls closed to the LLM;
a validation failure is never a parsed result.

Refs: #99

* Wire template-first parse into PO handler with EMF metric

Run try_deterministic_parse ahead of the Bedrock extractor and
fall back only on a miss/invalid (fail-closed) result. The shared
enrich_parsed post-stage and the save_cancellation/save_revision/
save_new_po routing are untouched, so both paths write identical
DynamoDB shapes and the po-ingest-site-extractor stream contract
is preserved.

Each record emits one ParseMethod EMF line (Seahaven/PoIngest/
ParseOutcome, dimension sets [ParseMethod] and
[ParseMethod,TemplateId], ReasonCode/po_number ride-alongs)
mirroring the WO idiom. The metric fires before the Bedrock call
so a Bedrock-side error still records the ai_fallback outcome.

Refs: #99

* Add PO fallback-rate alarm retuned for ~57 emails/day

The WO alarm's 15-min period and >=10-sample floor assume
~760/day and would be structurally dead at PO volume (a 15-min
period holds ~0.6 emails, so the floor is never met). Retune:
6-hour periods (~14.25 expected emails), IF((fb+tmpl)>=8,...)
volume floor so a single email can never breach a datapoint
(1/8 = 12.5% < 20%), threshold >20% against a ~1% expected
baseline, eval 4 / datapoints 2 (24h span) so noise self-clears
while total template drift pages within ~12h. No element-wise
MAX in the math expression (post-#102 rule); ALARM-only
SnsAction to site-alerts, NOT_BREACHING. Gated with
'npx cdk synth po-ingest'.

Also add template_parser.py to the bundling cp list -- without it
every deployed invocation would ImportError (unit tests cannot
catch an asset-bundling omission).

Refs: #99, #102

* Add offline PO parser suite with scrubbed fixture corpus

132 tests: golden-file comparison for all 25 positive fixtures
(17 single-line new-PO + 8 cancellations, Decimal-exact via
parse_float=Decimal), every fail-closed gate reason code covered
(body-level triggers via 17 synthetic adversarial .eml mutations,
candidate-level via direct validate() unit tests), real multi-line
and comment/non-Coupa fallback fixtures, dual line-ending parse
identity, two-path enrich/save parity (site-extractor stream
guard), V10 URL-id corpus sweep, fixture hygiene (ses_auth pass +
scrub-marker leak sweep), and Bedrock dispatch/EMF assertions.

The suite loads handler/template_parser via importlib under
unique module names and binds the handler's bare sibling imports
around exec (tests/conftest.py load_handler gets the same
treatment) -- the WO suite caches bare 'handler'/'template_parser'
names in sys.modules, and bare imports here would silently bind
to the wrong pipeline. moto is imported before the handler so its
botocore stubber hook precedes boto3 session creation (the PO
conftest chain now loads at pytest session start).

Fixtures are scrubbed real S3 samples: transport/auth header
values replaced with same-shape placeholders (structure kept so
ses_auth still passes), per-file digit ciphers, amounts remapped
with sum==total re-established. The .gitignore exception is
scoped to the PO fixtures path only.

Refs: #99

* Document PO template-first parser and retuned alarm

README: PO flow is now template-first with Bedrock fallback;
parser/gate section mirroring the WO writeup; Seahaven/PoIngest
ParseOutcome namespace and the fallback-rate alarm numbers with
their volume justification (deliberately not WO's settings);
test-suite and repo-layout updates.

Design doc: mark PR #1 complete in progress/checklist sections;
document the six value-level gate reason codes and the scaffold
guard removal; correct the stale data-access note (default CLI
session is 328440206208) and note the ~90-day S3 lifecycle aging
of the corpus; record the 2.3 layout addendum (leading Supplier
bullet segment, EA evidence lines, summary unit-price tokens,
decode-path line endings), the fixture-build pins (address join
convention, quantity/unit/price source), the V10 sweep outcome,
and resolutions for open questions Q3/Q6. Cross-family review and
the Confluence architecture-map update are flagged outstanding
for merge.

Refs: #99

* Record cross-family review outcome for handler wiring

GPT-4.1 cross_review.py run against the real handler diff
returned no BLOCK and no security findings; both FIX items
verified as no-change-needed (fallback logging already correct;
non-dict AI output is the pre-existing issue #101 pattern this
PR deliberately does not touch).

Refs: #99

* Pin line-item currency to USD in the PO gate

The non_usd rule only checked the Total-block top-level currency, so a
new_po whose line item read 'for 55,206.00 CAD' under a USD Total block
still template-parsed as ok -- a fail-open hole in the fail-closed
gate. Every line item's captured currency and its re-derived body token
must now byte-equal the proven-USD top-level currency; covered by a
line-level CAD adversarial fixture (the existing adv-non-usd only
exercised the Total-block variant) and a candidate-mutation unit test.

* Scrub residual transport tokens from PO fixtures

The first-pass harvest scrub sanitized only the primary SES/DKIM
header blocks, leaving the real SES Feedback-ID sender-identity hash
in 49 committed fixtures and, on the two non-Coupa fixtures, an
embedded second SES block's X-Ses-Receipt, the Exchange cross-tenant
UPN ciphertext, and Gmail ARC fh= / X-Gm-* tokens -- exactly the
token classes the PR #99 fixture lesson requires placeholdered.
Replace each with a same-shape ScrubbedFixture value (byte-safe,
CRLF and folding preserved) so header structure and ses_auth
behavior are unchanged.

* Converge quantity/price to Decimal on both paths

EXTRACTION_PROMPT declares quantity and price as JSON strings, so a
prompt-obedient Bedrock response stores DynamoDB Strings where the
template parser stores Numbers -- divergent attribute types for the
same email on the purchase-orders stream. Coerce numeric strings to
Decimal in the shared enrich_parsed post-stage (thousands-separator
safe; non-numeric strings kept verbatim) so both paths converge;
prompt rewording itself remains PR #2 scope.

The two-path parity test was circular -- it replayed the parser-
derived golden as 'the LLM output', so it could never see the type
divergence. It now feeds a prompt-shaped payload (string quantity/
price, LLM-filled site_code) through enrich_parsed and save_new_po,
and the fixture-hygiene test now asserts the scrubbed transport-token
header classes so fixture regressions are caught.

* Coerce bare-int quantity/price to Decimal in enrich_parsed

GPT-4.1 cross-family review of the final PR diff (no BLOCK) flagged
residual type drift: parse_float=Decimal rules out floats on the LLM
path, but a bare JSON int survived as Python int. Coerce it so both
parse paths emit one canonical Decimal type.

* Scrub fixture-body PII and harden cancellation gate (sec review)

/sh-security-review of PR #105 (5 fresh-context detectors + proof-or-kill
verifier) confirmed two diff-introduced findings; both fixed here.

F3 (medium, real PII in new fixtures): the harvest scrub replaced header
tokens but left real third-party PII in message BODIES -- an Amazon
contact's name/phone/personal email in non-coupa-02.eml and an internal
t.corp.amazon.com ticket URL in comment-02.eml, plus real submitter/attn
names recurring across the new_po corpus. Replaced every personal name,
phone, personal email, and internal URL with synthetic placeholders
(QP-soft-wrap aware) across both .eml bodies and expected goldens.
Extended test_fixture_hygiene to scan BODIES (phone shapes, corp URLs,
the leaked tokens), closing the header-only gap that let this through.

F1 (medium, cancellation gate): _CANCELLATION_SUBJECT was unanchored and
matched with .search(), unlike the anchored new_po pattern -- a subject
merely ending with the cancellation phrase could be routed to the sticky-
Cancelled write. Fully anchored it and switched to .match, and added a
body-corroboration gate (the real Coupa body independently restates
'Purchase Order #<po> ... has been cancelled'); a near-miss/misrouted
subject whose body does not corroborate now fails closed to the LLM
(new reason code cancellation_body_unconfirmed).

Pre-existing (advisory, not this PR): the LLM-fallback else->save_new_po
dispatch and undelimited extraction prompt (issue #101 family) are
byte-identical to main and unchanged here.

401 tests pass; ruff/format clean; cdk synth po-ingest clean.

---------

Signed-off-by: Adam Moussa <166072409+amoussa1229@users.noreply.github.com>
2026-07-16 17:50:59 -04:00