docs(worker): Gate F runbook for docling shadow extraction (packet B4)

[BigSimmo]

Summary

• Adds a full §3 Docling shadow extraction (packet B4 — default OFF) section to docs/worker-deploy-runbook.md. This is the Gate F artifact for packet B4 (README §Gates A–F: flag, one-step rollback, runbook, cost cap, redacted telemetry). B4 shipped the flag, the rollback and the numbers-only telemetry in PR feat(worker): packet B4 — docling shadow extraction mode (WORKER_DOCUMENT_EXTRACTOR_MODE=legacy|shadow, default legacy) #2170; the runbook and the stated cost cap were the missing legs, so no document told an operator how to enable shadow mode, what it costs, what to watch, or when to roll back.
• Replaces the short bullet list PR feat(worker): packet B4 — docling shadow extraction mode (WORKER_DOCUMENT_EXTRACTOR_MODE=legacy|shadow, default legacy) #2170 left inside the "Secrets and env" subsection of the run recipe with a pointer to the new section, so the two cannot drift apart. Renumbers the two sections that followed (Verify → §4, Troubleshooting → §5); no inbound reference anywhere in the repository pins a section number of this runbook.
• Cross-references the new flag rollback from the existing image-rollback section at the end of the runbook, since an operator turning shadow mode off does not need to redeploy a previous image tag.
• Updates the one-line description of the runbook in docs/README.md so the operations index names shadow extraction.
• Queues one P3 issue request (docs/outstanding-issues-inbox/219680d3-…json) covering the operational values this runbook could not verify from the repository — see Notes.

Every operational number in the new section is verified from the code or from the Gate B decision record of 2026-08-18, not assumed:

• Preconditions. The running image must be built from main at or after PR feat(worker): packet B4 — docling shadow extraction mode (WORKER_DOCUMENT_EXTRACTOR_MODE=legacy|shadow, default legacy) #2170 (5437c309f) — an older image leaves WORKER_DOCLING_PYTHON_BIN unset and records runtime_unavailable for every cohort document. Memory headroom of roughly 1.5 GiB above the worker's current peak, from Gate B's measured docling peak RSS of 1,504,313,344 B (~1.40 GiB) against the lab's 6 GiB cap, with the Railway dashboard path for checking it and the reason it is the precondition that matters most (a container OOM kill during the docling window is the one failure the fail-open code cannot catch). WORKER_CONCURRENCY=1. A read path for documents.metadata. Actual ingestion traffic, because shadow mode never backfills.
• The variables and their safe values.WORKER_DOCUMENT_EXTRACTOR_MODE, WORKER_SHADOW_EXTRACTION_COHORT_PERCENT and WORKER_DOCLING_PYTHON_BIN, each with its src/lib/env.ts contract. Why 2 is the approved start: the cohort is deterministic and salted (docling-shadow-v1) and the predicate is bucket < percent, so raising it later is purely additive and never re-rolls or discards an already-measured document — starting low costs nothing later.
• Cost and throughput cap, derived from Gate B's measured 9–19 s/doc for docling versus ~1 s legacy on 2 CPUs, against the 2851-document corpus (measured 2026-08-19, ledger #1K6T35). At 2 %: ≤ ~57 cohort documents per full pass, ~9–18 min added worker time, ceiling ~114 min at the 120 s timeout. At 5 %: ≤ ~142 documents, ~21–45 min, ceiling ~284 min. The section states plainly that the 9–19 s band is a floor rather than a forecast because it was measured on small lab fixtures, that both cohort counts are upper bounds on bucket hits, and that the proportion of total reindex wall clock is not derivable from this repository.
• What shadow mode never writes, stated explicitly: no chunk, embedding, index unit, table fact, document_index_quality row, page or image; no new writer and no state transition; search and ranking never read the record; and the record is redacted by construction. Also the one real user-visible effect, which the previous text did not mention: retrieval filters status = 'indexed' and the status flip happens after the shadow window, so a cohort document becomes searchable up to about two minutes later than it would in legacy mode.
• What to watch in the first 24 hours: the three places to look (worker logs, reindex:health, the aggregate record), a read-only SQL query for documents.metadata->'shadow_extraction', expected record volume, and a table of the specific values that mean healthy versus investigate — runtime_unavailable / process_error / skipped_concurrent at 0, wall_ms against the Gate B P95 of 12,558 ms, peak_rss_bytes around 1.4 GiB, delta.page_count at 0, the two delta ratios near 1.0.
• Named rollback triggers, split into immediate (container OOM or restart loop, queue stops draining, any job failure attributable to a fail-open path) and next-convenient (universal runtime_unavailable, sustained timeouts, sustained memory above the confirmed headroom), plus the one-step rollback with its worker-side time to take effect bounded.
• An explicit statement that no promotion argument based on table quality may be made from shadow numbers until docling-lab-fixtures.v2 lands (queued request a20fc4ce), per the first Gate B caveat, with the reason: the table-heavy leg passed at parity-on-ceiling because every v1 table fixture is cleanly ruled and puts both engines at cell F1 1.0.

Verification

• npm run verify:pr-local — run in full on the committed change. It classified the diff as recognised low-risk documentation scope (skipping lint, typecheck, the unit suite, the offline RAG checks and the build) and ran eleven gates, all of which passed:

  PR-local verification summary:
  - completed: check:runtime, check:installed-lock-parity, format:changed, sitemap:check, docs:check-index,
  docs:check-inventory, docs:check-scripts, docs:check-links, check:branch-review-ledger,
  check:outstanding-issues, check:ledger-write-discipline
  - failed: (none)
  - not reached: (none)
  

  Decisive lines from the documentation and ledger gates:

  docs link check passed: 2054 repo path references resolve.
  docs/codebase-index.md coverage OK: all 54 repository roots/modules/routes and all schema tables are indexed.
  docs script-ref check passed: 524 npm-run reference(s) resolve to real scripts.
  Docs inventory current: 249 script files, 252 npm scripts.
  Ledger inbox check passed: 5 pending request(s), 404 applied.
  Outstanding-issues guard passed: 403 rows (67 open, 336 archived), unique display and durable ids, ...
  Ledger write discipline passed for 2abbe0068560..HEAD.
  Branch review ledger guard passed: 880 live table records + 1206 archived + 409 immutable ...
  

  npm run format was run and its result committed before push; prettier --check on the changed files reports All matched files use Prettier code style!.

• npm run verify:ui — UI verification not run: no UI, routing, styling, browser, reduced-motion or forced-colors behaviour changed. The diff is three files under docs/.

• npm run verify:release — Verification not run: no release or handoff confidence claim is being made, and the gate is provider-backed.

• npm run eval:retrieval:quality — Verification not run: no retrieval, ranking, selection, chunking or scoring behaviour changed, and the gate is provider-backed.

• npm run eval:rag -- --limit 15 + npm run eval:quality -- --rag-only — Verification not run: no answer generation, synthesis prompt or answer post-processing changed, and both are provider-backed.

• npm run check:production-readiness — Verification not run: no clinical workflow, privacy, environment, Supabase, source governance or deployment behaviour changed. The runbook documents an operator variable that already exists and already ships defaulted to legacy; this diff changes no default and no configuration.

• npm run check:deployment-readiness — Verification not run: no deployment startup, hosting or rollout behaviour changed.

Risk and rollout

• Risk: Very low. Documentation only. No source, worker, Supabase, workflow or configuration file is touched, no default is changed, and shadow extraction is not enabled anywhere. The residual risk is that an operator follows a number in the runbook that later proves wrong for the live corpus; the section addresses this by naming its source for every figure, by marking the Gate B 9–19 s band as a floor rather than a forecast, and by flagging the values that could not be verified from the repository rather than inventing them.
• Rollback: git revert the single commit. Nothing operational depends on it.
• Provider or production effects: None. The only provider access in producing this change was the read-only open-PR duplicate check required by #292, which found no open PR touching this runbook or the docling surface (open PRs at the time: feat(sitemap,indexing): audit indexing, wire dynamic formulation metadata, and complete sitemap inventory #2189, fix: resolve 29 audit findings across clinical safety, privacy, worker, and api domains #2188, and three draft dependabot PRs). The runbook instructs an operator to make provider-touching reads — Railway metrics, npm run reindex:health, a read-only Supabase query — and labels each as requiring explicit approval; none was performed here, and no Railway or Supabase mutation of any kind was made.
• RAG impact: no retrieval behaviour change — operator documentation only. No file under src/lib/rag/, no retrieval RPC, no ranking surface, no golden fixture and no ranking contract test is touched; the diff is three files under docs/.

Clinical Governance Preflight

Not applicable to this change, and not required by policy. classifyPullRequestFiles in scripts/pr-policy.mjs returns clinicalRisk: false for this diff: docs/README.md, docs/worker-deploy-runbook.md and a docs/outstanding-issues-inbox/*.json request match none of the clinical-risk, operational-risk or RAG-ranking path patterns. The change touches no ingestion, answer generation, search/ranking, source rendering, document access, privacy, production environment or clinical output behaviour — it describes an existing, default-off worker flag. For completeness: the Supabase target named in the new section is the pinned live project Clinical KB Database (sjrfecxgysukkwxsowpy), and the sample query it offers an operator is read-only.

Notes

• The task premise was partly wrong, and the diff reflects the corrected version. PR feat(worker): packet B4 — docling shadow extraction mode (WORKER_DOCUMENT_EXTRACTOR_MODE=legacy|shadow, default legacy) #2170 did leave a short B4 subsection in this runbook, inside "Secrets and env" — it was not nothing. But it was missing most of what Gate F asks for: no cost or throughput cap expressed as added worker time, no first-24-hours watch list, no healthy-versus-investigate numbers, no named rollback triggers, no time to take effect for the rollback, no statement of why 2 is the approved cohort value or what 5 would cost, and no image-vintage precondition. Rather than add a second B4 section and let the two drift, this promotes the material into a full section and leaves a pointer behind.
• Two claims in that older text were corrected against the code. It implied shadow mode has no user-visible effect, whereas documents.status flips to indexed only after the shadow window and every retrieval RPC filters on that status. And its "≤ ~57 cohort documents per full reindex" is an upper bound on bucket hits, not on the cohort, because non-PDFs and PDFs carrying no tables/OCR/layout signal drop out of the predicate.
• Kept in the runbook rather than as a standalone document, per the preference for avoiding doc sprawl. The section only makes sense to someone who has read §1 (what ships in the image) and §2 (the run recipe and env), it shares their operator audience and Railway context, and its flag rollback needs to sit next to the image rollback it is deliberately not.
• Values that could not be verified from the repository are marked as such in the text rather than guessed: Railway's own behaviour on a variable change (restart versus full rebuild), which bounds the real-world rollback time; the Railway worker service's memory limit and observed peak, which the headroom precondition asks the operator to read in the dashboard; and the proposed ">10 % of cohort runs timing out" rollback threshold, which is an operating rule needing owner ratification rather than a measurement. Queued as one P3 request, together with the observation that no npm script reads, exports or clears the shadow records, so the first-24-hours watch is currently a hand-run SQL query.
• The Gate B decision record's second caveat — docling's eager-mode latency — is carried in §3.4 as the reason the cohort is bounded three ways; the first caveat has its own subsection (§3.8).

Summary by CodeRabbit

• Documentation
  • Expanded the worker deployment runbook with a default-off Docling shadow-extraction procedure.
  • Added guidance for configuration, redaction, prerequisites, cost limits, monitoring, rollback, and evidence limitations.
  • Clarified the distinction between image rollback and Docling feature rollback.
  • Updated the README and tracked remaining documentation gaps and verification items.

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📝 Walkthrough

Walkthrough

The pull request expands the worker deployment runbook with a default-off Docling shadow-extraction procedure. It documents behavior, configuration, enablement, monitoring, rollback, evidence limits, and related follow-up requirements.

Changes

Docling shadow extraction

Layer / File(s)	Summary
Shadow-extraction behavior and configuration docs/README.md, docs/worker-deploy-runbook.md	The documentation defines deterministic PDF cohort processing, redacted aggregate metadata, fail-open behavior, prerequisites, environment variables, validation bounds, cost limits, and corpus projections.
Enablement and monitoring docs/worker-deploy-runbook.md	The runbook adds enablement steps, restart requirements, prerequisite handling, startup messages, queue monitoring, log checks, and outcome thresholds.
Rollback and evidence boundaries docs/worker-deploy-runbook.md, docs/outstanding-issues-inbox/*.json	The runbook documents immediate and deferred rollback triggers, flag rollback, image rollback scope, section renumbering, and limits on promotion evidence. The issue record lists unresolved validation work.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk:🔵 Low · up to 0ec44

This change only updates operator documentation and does not alter worker behavior or defaults. A few bounded follow-ups remain to align issue metadata and dates, clarify cohort-volume and cost figures for configurable percentages, and restore review traceability; the PR is otherwise mergeable with explicit owner awareness.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the documentation change: a Gate F runbook for Docling shadow extraction.
Description check	✅ Passed	The description covers the template sections, verification results, risk, rollback, effects, RAG impact, governance, and notes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Commit unit tests in branch claude/docling-shadow-extraction-runbook-942862

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In `@docs/outstanding-issues-inbox/219680d3-050e-40d4-bd95-f511420ac3cb.json`:
- Around line 9-10: The issue summary in the outstanding-issue record does not
cover all unknowns described in its detail. Update the summary to include
Railway variable-change behavior, the shadow-record read path, timeout rollback
threshold, and memory headroom, while preserving the existing documentation and
read-only script scope.
- Line 10: The detail’s section-added date conflicts with the entry’s createdOn
date. Update the section 3 date in the detail to a date no later than
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keeping both metadata values consistent.
In `@docs/README.md`:
- Line 53: Update the documentation ledger to add or resolve the “Shadow
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