#!/usr/bin/env bash
# doc-drift.sh — Plane-1 / Tier-1 checker for the R720 agent-team.
#
# Design refs: docs/r720-agent-team-design.md §4 (Tier 1 roster: doc-drift —
# "Flags repos whose architecture moved but Confluence/README did not") and §7 Phase 3
# ("doc-drift + step-ca/Roles Anywhere + aws-posture"). This is the THIRD Plane-1 checker
# built on the Phase-0 shared substrate (lib/sweep_substrate.sh); it mirrors
# compliance-drift.sh / dependency-cve.sh conventions VERBATIM so the coordinator (§5) can
# drive all of them identically. doc-drift is UNGATED (only aws-posture in this phase is
# hard-gated behind the GPT-4.1 IAM cross-review; that checker is NOT built here).
#
# WHAT IT DOES (read-only):
#   Scans the SAME shallow clean clones nightly_sweep.sh already produced in $MIRROR_DIR — it
#   does NOT re-clone (mirrors-first; an optional --refresh re-runs discovery+mirror via the
#   shared substrate). In each mirror it flags repos whose ARCHITECTURE MOVED but the README
#   DID NOT — i.e. documentation drift. The checklist is DETERMINISTIC and GROUNDED in the
#   global CLAUDE.md README obligation; it does NOT invent fuzzy judgments. See "CHECKLIST".
#
#   This phase is the deterministic core ONLY. The design's "Gemini (large context)" judge
#   layer (§4) is a LATER enhancement: a clearly-marked inert stub hook (maybe_judge) marks
#   the future seam; it does NOTHING offline and NOTHING in this phase.
#
# REPORTING (matches secrev sweep conventions):
#   - Writes a per-run JSON + text report under $REPORT_ROOT/<UTC-date>/, mode 600 (umask 077).
#   - Slack ALARM-ONLY: a clean run (no confirmed drift) posts NOTHING (memory
#     feedback_cloudwatch_alarms). Secret-shaped values are redacted from the Slack string.
#   - Reuses the substrate's redact() + post_slack_alarm() verbatim.
#
# SUBSTRATE REUSE (lib/sweep_substrate.sh, sourced — bash dynamic scoping):
#   redact, post_slack_alarm   -> Slack delivery (reads SLACK_WEBHOOK_URL, REPORT_DIR, SWEEP_LOG)
#   discover_repos, mirror_repo-> ONLY on --refresh (reads GH_TOKEN, GH_ORG, MIRROR_DIR, REPORT_DIR)
#   Default path enumerates EXISTING $MIRROR_DIR/*/.git dirs — zero clones, zero network.
#
# CANARY / DRY-RUN (offline, no network, no token):
#   --canary runs the checklist against a planted-drift fixture (checkers/fixtures/doc-drift/)
#   and asserts the known drift count. This is the anti-complacency floor (design §6.4) AND the
#   routing dry-run (§7 Phase 3): with --dry-run, the Slack alarm is composed + printed but NOT
#   POSTed. Fully offline-smoke-testable (the checks are filesystem + `git log`, no network).
#
# SCOPE / SAFETY:
#   Read-only. All checks are filesystem + local `git log`; NO network, NO token, NO GitHub API
#   (doc-drift has no API-only checks — it is purely tree+history). Fixtures ship git metadata as
#   dotgit/ (renamed to .git/ at run time) so they commit into THIS repo without becoming
#   submodules — the SAME trick compliance-drift / dependency-cve use. A repo with NO README is
#   SKIPPED (compliance-drift owns readme-present); doc-drift never double-flags a missing README.
#
# This script does NOT touch agent_team/ or agent-team/, is NOT wired into systemd, and does NOT
# stand up step-ca / Roles Anywhere / aws-posture — that is Phase-3/6 provisioning (gated). See
# the "PROVISIONING (NOT DONE HERE)" note at the bottom.
#
# Exit: 0 = ran (whether or not it alarmed); 2 = setup/usage error; 3 = canary assertion FAILED.
set -euo pipefail
export PATH="$HOME/.local/bin:/opt/homebrew/bin:/usr/local/bin:$PATH"

log() { echo "[doc-drift] $*" >&2; }
die() { echo "[doc-drift] FATAL: $*" >&2; exit 2; }

# --- Shared substrate ---------------------------------------------------------
HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
SUBSTRATE="$HERE/../lib/sweep_substrate.sh"
[ -f "$SUBSTRATE" ] || die "shared substrate not found: $SUBSTRATE"
# shellcheck source=../lib/sweep_substrate.sh
. "$SUBSTRATE"

# --- Config + defaults (env, all optional) ------------------------------------
GH_ORG="${GH_ORG:-Sea-Haven-Industries}"
MIRROR_DIR="${MIRROR_DIR:-$HOME/repo-mirrors}"
REPORT_ROOT="${REPORT_ROOT:-$HOME/sweep-reports/doc-drift}"
# Docs-only repos describe themselves differently (a handbook is its own doc); skip the
# architecture-omission scan for them. They still get the staleness check.
DOCS_ONLY_REPOS="${DOCS_ONLY_REPOS:-engineering-handbook}"
# Staleness thresholds: README must lag the newest code by BOTH at least this many days AND
# this many substantial code commits before we call it drift (two-factor = no false alarm on a
# single quick fix landed after a doc commit; memory feedback_cloudwatch_alarms).
DOC_DRIFT_STALE_DAYS="${DOC_DRIFT_STALE_DAYS:-60}"
DOC_DRIFT_STALE_COMMITS="${DOC_DRIFT_STALE_COMMITS:-3}"

REFRESH=0           # --refresh: re-run discovery+mirror via substrate (network). Default: reuse mirrors.
DO_API=1            # --no-api: accepted for interface-parity with the other checkers; doc-drift makes
                    #           NO API calls, so this flag is a documented no-op (kept so the coordinator
                    #           can pass a uniform flag set to every Tier-1 checker).
DRY_RUN=0           # --dry-run: compose the Slack alarm but DO NOT post it (routing dry-run).
CANARY=0            # --canary: run against the planted-drift fixture + assert the known count.
TARGETS_OVERRIDE="" # --targets "p1 p2": scan explicit dirs instead of the mirror set.

usage() {
  cat >&2 <<EOF
doc-drift.sh — Plane-1 Tier-1 documentation-drift checker (read-only)

  --canary          run against the planted-drift fixture and assert the known drift count
                    (implies --dry-run; fully offline smoke test — no network, no token)
  --dry-run         compose the Slack alarm but DO NOT post it (routing dry-run)
  --no-api          accepted for parity with the other Tier-1 checkers; doc-drift makes NO
                    API calls, so this is a documented no-op
  --refresh         re-discover + re-mirror via the shared substrate before scanning (network)
  --targets "a b"   scan these explicit repo dirs instead of \$MIRROR_DIR/* (no clone)
  -h|--help         this help

Env: GH_ORG MIRROR_DIR REPORT_ROOT GH_TOKEN SLACK_WEBHOOK_URL DOCS_ONLY_REPOS
     DOC_DRIFT_STALE_DAYS DOC_DRIFT_STALE_COMMITS
EOF
}

while [ $# -gt 0 ]; do
  case "$1" in
    --canary)   CANARY=1; DRY_RUN=1 ;;
    --dry-run)  DRY_RUN=1 ;;
    --no-api)   DO_API=0 ;;
    --refresh)  REFRESH=1 ;;
    --targets)  shift; TARGETS_OVERRIDE="${1:-}" ;;
    -h|--help)  usage; exit 0 ;;
    *) die "unknown arg: $1 (see --help)" ;;
  esac
  shift
done

command -v jq  >/dev/null || die "jq is required"
command -v git >/dev/null || die "git is required"

# --- Report dir (mode 600 reports; matches sweep conventions) -----------------
umask 077
UTC_DATE="$(date -u +%Y-%m-%d)"
UTC_STAMP="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
REPORT_DIR="$REPORT_ROOT/$UTC_DATE"
mkdir -p "$REPORT_DIR"; chmod 700 "$REPORT_ROOT" "$REPORT_DIR" 2>/dev/null || true
# shellcheck disable=SC2034  # read by the sourced substrate (post_slack_alarm) via dynamic scope
SWEEP_LOG="$REPORT_DIR/doc-drift.log"   # name the substrate's post_slack_alarm() references
REPORT_JSON="$REPORT_DIR/doc-drift.json"
REPORT_TXT="$REPORT_DIR/doc-drift.txt"

# doc-drift makes NO API calls, so DO_API is a documented no-op kept only for coordinator
# flag-parity; surface it in the run banner so the chosen value is auditable (and used).
log "=== doc-drift $UTC_STAMP (canary=$CANARY dry_run=$DRY_RUN refresh=$REFRESH api=${DO_API}[no-op] stale_days=$DOC_DRIFT_STALE_DAYS stale_commits=$DOC_DRIFT_STALE_COMMITS) ==="

# ------------------------------------------------------------------------------
# CHECKLIST (grounded — every item cites the README obligation; nothing invented):
#
#   readme-omits-component  README exists but omits a major existing component
#                           present in the tree (top-level service dir, SAM/CDK stack,
#                           Lambda handler dir, openapi/docs API spec)
#                           -> global CLAUDE.md: "README must accurately describe
#                              architecture, services, data flow, and configuration"
#   readme-stale-vs-code    README last-touched commit far older than the newest code
#                           commit (>= DOC_DRIFT_STALE_DAYS) AND >= DOC_DRIFT_STALE_COMMITS
#                           substantial code commits landed after the README was touched
#                           -> global CLAUDE.md: "update the README in the same commit"
#
# A repo with NO README is SKIPPED (compliance-drift owns readme-present; double-flagging would
# be a false alarm). Each emitted finding follows the spirit of finding.schema.json
# (id/title/severity/category/proof/status) so the coordinator can route it like an agentic
# finding. category="other" (doc drift is not one of the schema's security categories).
# status="confirmed" only for deterministic filesystem/git-history facts. The future Gemini
# judge (design §4) is an inert stub (maybe_judge) — never invoked offline / in this phase.
# ------------------------------------------------------------------------------

# Drift accumulator: one JSON object per finding, appended to a bash array.
declare -a FINDINGS=()
add_finding() {  # repo id title severity check proof
  local repo="$1" id="$2" title="$3" sev="$4" check="$5" proof="$6"
  FINDINGS+=( "$(jq -n \
    --arg repo "$repo" --arg id "$id" --arg title "$title" --arg sev "$sev" \
    --arg check "$check" --arg proof "$proof" \
    '{repo:$repo, id:($repo+"-"+$id), title:$title, severity:$sev, category:"other",
      check:$check, status:"confirmed", proof:{outcome:$proof}}')" )
}
declare -a SKIPPED_CHECKS=()   # (repo:check) checks skipped on missing data — reported, never alarmed
note_skip() { SKIPPED_CHECKS+=( "$1" ); }

in_csv() {  # needle csv  -> 0 if present
  local n="$1" csv="$2"; case ",$csv," in *",$n,"*) return 0 ;; *) return 1 ;; esac
}

# Inert future seam (design §4 "Gemini (large context)" judge): in LIVE mode an ambiguous
# omission ("is this component material enough to require a README mention?") could be escalated
# to a large-context judge. This phase keeps the deterministic core ONLY — the stub does nothing
# and is never reached offline / in canary / dry-run.
maybe_judge() {  # candidate_json  (no-op stub; Phase-3 intentionally inert)
  return 0
}

# --- Does a README mention a component name? (case-insensitive, word-ish, deterministic) ----
# Matches the bare name OR the name with a trailing slash (how a dir is usually cited). Strips
# a leading "the " never matters; we test the literal token. Pure grep, no fuzzy matching.
readme_mentions() {  # readme_file name
  local rf="$1" name="$2"
  # Escape regex metacharacters in the component name (defensive; dir names are usually plain).
  local esc; esc="$(printf '%s' "$name" | sed -E 's/[][(){}.*+?^$|\\/]/\\&/g')"
  grep -qiE "(^|[^A-Za-z0-9_-])${esc}([^A-Za-z0-9_-]|/|$)" "$rf" 2>/dev/null
}

# --- Enumerate the major components present in a repo tree (deterministic) ------
# Emits "TYPE<TAB>label<TAB>mention_token" lines. mention_token is what the README must contain.
#   service-dir   a top-level directory whose name ends in -service or -api, or named api/web/worker
#   sam-cdk-stack a SAM/CDK stack root (template.yaml | app.py at a stack root | cdk.json)
#   lambda-dir    a Lambda handler dir (a dir named handlers/ or containing handler.* / app.py under handlers/)
#   api-spec      an openapi/ or docs/ directory or an openapi.* / swagger.* spec file
enumerate_components() {  # repo_dir -> TSV lines
  local dir="$1" d nm

  # 1) top-level service-ish directories (the unit a README is expected to name)
  for d in "$dir"/*/; do
    [ -d "$d" ] || continue
    nm="$(basename "$d")"
    case "$nm" in
      .git|.github|node_modules|dist|build|vendor|__pycache__|.venv) continue ;;
    esac
    case "$nm" in
      *-service|*-api|api|web|worker|backend|frontend)
        printf 'service-dir\t%s\t%s\n' "$nm" "$nm" ;;
    esac
  done

  # 2) SAM / CDK stack roots
  if [ -f "$dir/template.yaml" ] || [ -f "$dir/template.yml" ]; then
    printf 'sam-cdk-stack\t%s\t%s\n' "template.yaml (SAM stack)" "template.yaml"
  fi
  if [ -f "$dir/cdk.json" ]; then
    printf 'sam-cdk-stack\t%s\t%s\n' "cdk.json (CDK app)" "cdk.json"
  fi

  # 3) Lambda handler dirs: a top-level/handlers-rooted dir literally named "handlers"
  while IFS= read -r d; do
    [ -n "$d" ] || continue
    printf 'lambda-dir\t%s\t%s\n' "handlers/ (Lambda handlers)" "handlers"
    break   # one mention requirement for the handlers tree is enough
  done < <(find "$dir" -maxdepth 2 -type d -name handlers -not -path '*/.git/*' 2>/dev/null)

  # 4) API spec: an openapi/ or docs/ dir, or an openapi.*/swagger.* file
  if [ -d "$dir/openapi" ]; then
    printf 'api-spec\t%s\t%s\n' "openapi/ (API spec)" "openapi"
  elif find "$dir" -maxdepth 2 \( -iname 'openapi.*' -o -iname 'swagger.*' \) -not -path '*/.git/*' -print -quit 2>/dev/null | grep -q .; then
    printf 'api-spec\t%s\t%s\n' "openapi/swagger spec" "openapi"
  fi
}

# --- README last-touch epoch vs newest code commit (staleness, deterministic git log) -------
# Returns the staleness facts on stdout as TSV "readme_epoch<TAB>newest_code_epoch<TAB>commits_after".
# commits_after = count of commits that touched code (non-doc) files AFTER the README's last touch.
# Code = anything that is NOT a README/markdown/LICENSE/.gitignore/docs file. Prints nothing if
# the repo has no git history or no README in history (caller treats that as "cannot assess").
readme_staleness_facts() {  # repo_dir
  local dir="$1"
  command -v git >/dev/null || return 0
  git -C "$dir" rev-parse --git-dir >/dev/null 2>&1 || return 0

  # README last-touch (committer epoch of the most recent commit touching README.md).
  local rd_epoch
  rd_epoch="$(git -C "$dir" log -1 --format='%ct' -- README.md 2>/dev/null || true)"
  [ -n "$rd_epoch" ] || return 0   # README not in history -> cannot assess staleness

  # Newest commit touching a CODE path (exclude docs/markdown/license/config-noise).
  local code_epoch
  code_epoch="$(git -C "$dir" log -1 --format='%ct' -- \
      ':(exclude)README.md' ':(exclude)*.md' ':(exclude)docs/**' \
      ':(exclude)LICENSE' ':(exclude).gitignore' ':(exclude).github/**' \
      2>/dev/null || true)"
  [ -n "$code_epoch" ] || return 0  # no code commits -> nothing to be stale against

  # Count CODE commits strictly AFTER the README's last touch.
  local commits_after
  commits_after="$(git -C "$dir" rev-list --count "--since=@${rd_epoch}" HEAD -- \
      ':(exclude)README.md' ':(exclude)*.md' ':(exclude)docs/**' \
      ':(exclude)LICENSE' ':(exclude).gitignore' ':(exclude).github/**' \
      2>/dev/null || echo 0)"
  printf '%s\t%s\t%s\n' "$rd_epoch" "$code_epoch" "${commits_after:-0}"
}

# ==============================================================================
# PER-REPO CHECK (offline; filesystem + local git log only)
# ==============================================================================
check_repo() {  # repo_name repo_dir
  local repo="$1" dir="$2"
  local docs_only=0; in_csv "$repo" "$DOCS_ONLY_REPOS" && docs_only=1

  # No README -> doc-drift cannot assess drift; compliance-drift owns readme-present. SKIP.
  if [ ! -f "$dir/README.md" ]; then
    note_skip "$repo:doc-drift(no-readme — compliance-drift owns readme-present)"
    return
  fi
  local readme="$dir/README.md"

  # --- readme-omits-component (skip for docs-only repos: they document differently) ---
  if [ "$docs_only" -eq 0 ]; then
    local type label token
    while IFS=$'\t' read -r type label token; do
      [ -n "$token" ] || continue
      if ! readme_mentions "$readme" "$token"; then
        add_finding "$repo" "readme-omits-$(printf '%s' "$type-$token" | tr -c 'A-Za-z0-9-' '-')" \
          "README omits existing component: $label" "medium" "readme-omits-component" \
          "global CLAUDE.md: README must accurately describe architecture/services (present in tree, absent from README: $label)"
      fi
    done < <(enumerate_components "$dir")
  else
    note_skip "$repo:readme-omits-component(docs-only)"
  fi

  # --- readme-stale-vs-code (two-factor: age in days AND code-commits-after) ---
  local facts; facts="$(readme_staleness_facts "$dir")"
  if [ -z "$facts" ]; then
    note_skip "$repo:readme-stale-vs-code(no-history-or-no-readme-in-history)"
  else
    local rd_epoch code_epoch commits_after age_days
    IFS=$'\t' read -r rd_epoch code_epoch commits_after <<< "$facts"
    age_days=$(( (code_epoch - rd_epoch) / 86400 ))
    [ "$age_days" -lt 0 ] && age_days=0
    if [ "$age_days" -ge "$DOC_DRIFT_STALE_DAYS" ] && [ "$commits_after" -ge "$DOC_DRIFT_STALE_COMMITS" ]; then
      add_finding "$repo" "readme-stale" \
        "README is stale: ${age_days}d behind newest code, ${commits_after} code commit(s) since last README touch" \
        "medium" "readme-stale-vs-code" \
        "global CLAUDE.md: update the README in the same commit as functionality changes (thresholds: >=${DOC_DRIFT_STALE_DAYS}d AND >=${DOC_DRIFT_STALE_COMMITS} code commits)"
    fi
  fi

  maybe_judge ""   # inert in this phase (future Gemini large-context seam)
}

# ==============================================================================
# TARGET RESOLUTION
# ==============================================================================
declare -a REPO_NAMES=(); declare -A REPO_DIR=()

if [ "$CANARY" -eq 1 ]; then
  FIXTURE_ROOT="$HERE/fixtures/doc-drift"
  [ -d "$FIXTURE_ROOT" ] || die "canary fixture missing: $FIXTURE_ROOT"
  # Pin the exception lists + thresholds the fixtures were authored against, so the canary is
  # self-contained and deterministic regardless of the operator's env.
  DOCS_ONLY_REPOS=""
  DOC_DRIFT_STALE_DAYS=60
  DOC_DRIFT_STALE_COMMITS=3
  # Fixtures ship their git metadata as `dotgit/` (not `.git/`) so they are committable into THIS
  # repo without becoming nested submodules. Materialize them into a temp work area — copy each
  # fixture and rename dotgit -> .git — so the README/git-log checks run against a real git
  # checkout. The temp area is mode 700 and removed on exit (same trick as compliance-drift.sh).
  FIXTURE_WORK="$(mktemp -d "${TMPDIR:-/tmp}/doc-drift-canary.XXXXXX")"
  trap 'rm -rf "$FIXTURE_WORK"' EXIT
  log "canary: materializing planted-drift fixtures from $FIXTURE_ROOT into $FIXTURE_WORK"
  for d in "$FIXTURE_ROOT"/*/; do
    [ -d "$d/dotgit" ] || continue           # only fixture repos (skip README.md, EXPECTED_* etc.)
    nm="$(basename "$d")"
    cp -R "$d" "$FIXTURE_WORK/$nm"
    mv "$FIXTURE_WORK/$nm/dotgit" "$FIXTURE_WORK/$nm/.git"
    REPO_NAMES+=( "$nm" ); REPO_DIR["$nm"]="$FIXTURE_WORK/$nm"
  done
elif [ -n "$TARGETS_OVERRIDE" ]; then
  # shellcheck disable=SC2206  # intentional word-split of the space-separated --targets list
  arr=( $TARGETS_OVERRIDE )
  for p in "${arr[@]}"; do p="${p/#\~/$HOME}"; nm="$(basename "$p")"; REPO_NAMES+=( "$nm" ); REPO_DIR["$nm"]="$p"; done
  log "explicit targets: ${REPO_NAMES[*]}"
else
  if [ "$REFRESH" -eq 1 ]; then
    [ -n "${GH_TOKEN:-}" ] || die "--refresh needs GH_TOKEN"
    command -v curl >/dev/null || die "--refresh needs curl"
    mkdir -p "$MIRROR_DIR"
    log "refresh: re-discovering + mirroring via shared substrate (no separate clone path)"
    DISCOVERED="$REPORT_DIR/discovered.tsv"
    if discover_repos > "$DISCOVERED" 2>>"$REPORT_DIR/discover.log" && [ -s "$DISCOVERED" ]; then
      while IFS=$'\t' read -r name url branch; do
        [ -n "$name" ] || continue
        mirror_repo "$name" "$url" "$branch" || log "  mirror FAILED: $name (will use stale mirror if present)"
      done < "$DISCOVERED"
    else
      log "discovery failed — falling back to existing mirrors (coverage may be stale)"
    fi
  fi
  # Default + post-refresh: enumerate EXISTING mirrors. No clone here — reuse the sweep's clones.
  [ -d "$MIRROR_DIR" ] || die "mirror dir not found: $MIRROR_DIR (run nightly_sweep.sh first, or use --refresh/--targets)"
  for d in "$MIRROR_DIR"/*/; do
    [ -d "$d/.git" ] || continue
    nm="$(basename "$d")"; REPO_NAMES+=( "$nm" ); REPO_DIR["$nm"]="${d%/}"
  done
  log "reusing ${#REPO_NAMES[@]} existing mirror(s) in $MIRROR_DIR (no re-clone)"
fi

[ "${#REPO_NAMES[@]}" -gt 0 ] || die "no repos to scan"

# ==============================================================================
# RUN CHECKS
# ==============================================================================
for nm in "${REPO_NAMES[@]}"; do
  check_repo "$nm" "${REPO_DIR[$nm]}"
done

# ==============================================================================
# ASSEMBLE REPORT (JSON + text), mode 600  (identical shape to compliance-drift)
# ==============================================================================
if [ "${#FINDINGS[@]}" -gt 0 ]; then
  FINDINGS_JSON="$(printf '%s\n' "${FINDINGS[@]}" | jq -cs .)"
else
  FINDINGS_JSON="[]"
fi
if [ "${#SKIPPED_CHECKS[@]}" -gt 0 ]; then
  SKIPPED_JSON="$(printf '%s\n' "${SKIPPED_CHECKS[@]}" | jq -R . | jq -cs .)"
else
  SKIPPED_JSON="[]"
fi

N_DRIFT="$(echo "$FINDINGS_JSON" | jq 'length')"
N_HIGH="$(echo "$FINDINGS_JSON"  | jq '[.[]|select(.severity=="high")]   | length')"
N_REPOS_DRIFTED="$(echo "$FINDINGS_JSON" | jq '[.[].repo] | unique | length')"

jq -n \
  --arg checker "doc-drift" --arg ts "$UTC_STAMP" --arg org "$GH_ORG" \
  --argjson scanned "${#REPO_NAMES[@]}" \
  --argjson findings "$FINDINGS_JSON" --argjson skipped "$SKIPPED_JSON" \
  '{checker:$checker, generated:$ts, org:$org,
    repos_scanned:$scanned, drift_count:($findings|length),
    repos_with_drift:([$findings[].repo]|unique|length),
    findings:$findings, skipped_checks:$skipped}' > "$REPORT_JSON"

{
  echo "doc-drift report — $UTC_STAMP"
  echo "org=$GH_ORG repos_scanned=${#REPO_NAMES[@]} stale_thresholds=${DOC_DRIFT_STALE_DAYS}d/${DOC_DRIFT_STALE_COMMITS}commits"
  echo "drift findings: $N_DRIFT ($N_HIGH high) across $N_REPOS_DRIFTED repo(s)"
  echo
  echo "$FINDINGS_JSON" | jq -r '.[] | "• [\(.severity)] \(.repo): \(.title)\n    rule: \(.proof.outcome)"'
  if [ "$(echo "$SKIPPED_JSON" | jq 'length')" -gt 0 ]; then
    echo; echo "skipped checks (missing data / not doc-drift's job — NOT counted as drift):"
    echo "$SKIPPED_JSON" | jq -r '.[] | "  - \(.)"'
  fi
} > "$REPORT_TXT"
chmod 600 "$REPORT_JSON" "$REPORT_TXT" 2>/dev/null || true

log "report: $REPORT_JSON ($N_DRIFT drift finding(s), $N_REPOS_DRIFTED repo(s))"

# ==============================================================================
# CANARY ASSERTION (anti-complacency floor, design §6.4)
# ==============================================================================
if [ "$CANARY" -eq 1 ]; then
  EXPECT_FILE="$HERE/fixtures/doc-drift/EXPECTED_DRIFT_COUNT"
  [ -f "$EXPECT_FILE" ] || die "canary expected-count file missing: $EXPECT_FILE"
  EXPECTED="$(tr -dc '0-9' < "$EXPECT_FILE")"
  log "canary assertion: expected drift=$EXPECTED, got=$N_DRIFT"
  if [ "$N_DRIFT" -ne "$EXPECTED" ]; then
    echo "[doc-drift] CANARY FAIL: planted-drift count mismatch (expected $EXPECTED, got $N_DRIFT)" >&2
    echo "  -> the checklist regressed (a check stopped firing) or the fixture changed. See $REPORT_TXT." >&2
    exit 3
  fi
  log "canary PASS: all $EXPECTED planted drifts detected."
fi

# ==============================================================================
# ALARM-ONLY ROUTING (clean = silent; memory feedback_cloudwatch_alarms)
# ==============================================================================
if [ "$N_DRIFT" -eq 0 ]; then
  log "no confirmed drift — posting NOTHING to Slack (ALARM-only policy)."
  exit 0
fi

ALARM_BODY="$(echo "$FINDINGS_JSON" | jq -r '
  group_by(.repo)[] | "*\(.[0].repo)*: " + ([.[] | "[\(.severity)] \(.title)"] | join("; "))' | sed 's/^/• /')"
SLACK_TEXT=":memo: *Sea Haven doc-drift — ALARM* ($UTC_STAMP)
$N_DRIFT documentation-drift finding(s) across $N_REPOS_DRIFTED repo(s) ($N_HIGH high):
$ALARM_BODY

Checks: README-omits-component · README-stale-vs-code (architecture moved, docs did not)
Report (mode 600): \`$REPORT_JSON\` (on R720)"
SLACK_TEXT="$(echo "$SLACK_TEXT" | redact)"

echo "$SLACK_TEXT" >&2

if [ "$DRY_RUN" -eq 1 ]; then
  log "DRY-RUN: alarm composed but NOT posted (routing dry-run, design §7 Phase 3)."
  exit 0
fi
post_slack_alarm "$SLACK_TEXT"
exit 0

# ==============================================================================
# PROVISIONING (NOT DONE HERE — gated, Phase 3 / Phase 6):
#   - No systemd unit / timer is installed by this script. Wiring it into the live
#     sea-haven-secrev schedule (or a sibling timer) is provisioning and is gated.
#   - This script is NOT registered in checker_coordinator.sh; the coordinator registry is
#     integrated centrally (separate change), so doc-drift is not yet driven by the coordinator.
#   - step-ca / IAM Roles Anywhere / the read-only AWS role / aws-posture are NOT stood up or
#     built here. The IAM artifacts authored alongside this checker (security-review/iam/) are
#     FILES for the mandatory GPT-4.1 cross-review; aws-posture itself is hard-gated behind that
#     review and is built only after it is recorded (design §7, B3).
#   - The LIVE "Gemini (large context)" doc-drift judge (design §4) is the only LLM seam; it is
#     an inert stub here (maybe_judge) and stays off in canary / dry-run / offline.
#   - Confluence + project_r720_agent_team memory updates are docs-as-you-go obligations for the
#     build session, tracked outside this script.
# ==============================================================================