> For the complete documentation index, see [llms.txt](https://ai-os-and-trend-finder.gitbook.io/ai-os-and-trend-finder-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ai-os-and-trend-finder.gitbook.io/ai-os-and-trend-finder-docs/.spec_system/archive/sessions/phase29-session08-required-derived-field-closeout-gate/implementation-notes.md).

# Implementation Notes

**Session ID**: `phase29-session08-required-derived-field-closeout-gate` **Started**: 2026-06-20 22:53 **Last Updated**: 2026-06-20 23:07

***

## Session Progress

| Metric              | Value   |
| ------------------- | ------- |
| Tasks Completed     | 20 / 20 |
| Estimated Remaining | 0 hours |
| Blockers            | 0       |

***

## Task Log

### 2026-06-20 - Session Start

**Environment verified**:

* [x] Prerequisites confirmed
* [x] Tools available
* [x] Directory structure ready

***

### Task T001 - Verify analyzer state, prerequisites, and scope

**Started**: 2026-06-20 22:52 **Completed**: 2026-06-20 22:53 **Duration**: 1 minute

**Notes**:

* Ran the local spec analyzer and confirmed current session `phase29-session08-required-derived-field-closeout-gate`.
* Ran environment and Bun prerequisite checks; both passed with Bun 1.3.14.
* Read the Session 08 PRD stub and confirmed the scope is the required-derived-field closeout gate.

**Files Changed**:

* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/implementation-notes.md` - initialized progress log for the session.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T001 complete.

***

### Task T002 - Inspect collector, schema, static export, QA, payload reporter, and tests

**Started**: 2026-06-20 22:53 **Completed**: 2026-06-20 22:54 **Duration**: 1 minute

**Notes**:

* Confirmed collector validation currently relies on `TrendFinderDataSchema.safeParse()` and final collection writes snapshots after browser diagnostics slimming and vector-array safety checks.
* Confirmed static Brief export loads raw extension data, privacy-scans it, validates through schema defaults, then projects and renders before QA.
* Confirmed static Brief QA already supports blocking issue output and privacy scans, while the payload-size reporter already includes the required derived branches.
* Reviewed existing collector, static export, fixture, view-model, and e2e test patterns for focused coverage.

**Files Changed**:

* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/implementation-notes.md` - logged baseline inspection.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T002 complete.

***

### Task T006 - Preserve schema defaults and export closeout field metadata

**Started**: 2026-06-20 22:55 **Completed**: 2026-06-20 22:56 **Duration**: 1 minute

**Notes**:

* Added exported required-derived topic and report field constants/types for closeout consumers.
* Left `TrendFinderDataSchema`, `parseTrendFinderData()`, and `validateTrendFinderData()` default behavior unchanged for legacy payload parsing.

**Files Changed**:

* `src/extensions/trend-finder/schema.ts` - exported closeout field metadata without changing schema parsing.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T006 complete.

**BQC Fixes**:

* Contract alignment: kept the new closeout field list typed against `TrendTopic` and `TrendFinderData` keys.

***

### Task T003 - Create required-derived-fields helper contract

**Started**: 2026-06-20 22:56 **Completed**: 2026-06-20 22:57 **Duration**: 1 minute

**Notes**:

* Created a reusable helper with typed closeout scopes, issue codes, sanitized issue shape, capped issue collection, formatting, and a dedicated closeout error.

**Files Changed**:

* `scripts/extensions/trend-finder/required-derived-fields.ts` - added helper contract and safe issue formatting.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T003 complete.

**BQC Fixes**:

* Error information boundaries: closeout issue formatting includes only scope, code, field, path, topic ID, and omitted count.

***

### Task T005 - Define required topic and report fields

**Started**: 2026-06-20 22:56 **Completed**: 2026-06-20 22:57 **Duration**: 1 minute

**Notes**:

* Defined required topic fields for `attentionPattern`, `receptionSignal`, `corroboration`, and `evidenceRationales`.
* Defined the required report branch for `runNarratives`.
* Recorded defaults-aware shape rules: string for attention/reception, object for corroboration/rationales, array for run narratives.

**Files Changed**:

* `scripts/extensions/trend-finder/required-derived-fields.ts` - added field definitions and shape map.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T005 complete.

**BQC Fixes**:

* Contract alignment: helper field names are imported from schema-exported typed constants.

***

### Task T008 - Implement topic derived field closeout assertion

**Started**: 2026-06-20 22:56 **Completed**: 2026-06-20 22:57 **Duration**: 1 minute

**Notes**:

* Added deterministic topic iteration, missing-field detection, wrong-shape detection, safe topic ID fallback, and capped issue output.

**Files Changed**:

* `scripts/extensions/trend-finder/required-derived-fields.ts` - implemented topic field issue collection.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T008 complete.

**BQC Fixes**:

* Trust boundary enforcement: helper validates raw objects with explicit type checks instead of trusting schema-defaulted values.
* Error information boundaries: unsafe topic IDs fall back to `topic-index-N`.

***

### Task T009 - Implement report-level derived branch assertion

**Started**: 2026-06-20 22:56 **Completed**: 2026-06-20 22:57 **Duration**: 1 minute

**Notes**:

* Added report-level presence and shape checks for `runNarratives`, allowing an empty array while rejecting missing or non-array branches.

**Files Changed**:

* `scripts/extensions/trend-finder/required-derived-fields.ts` - implemented report field issue collection and assertion entry point.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T009 complete.

**BQC Fixes**:

* Failure path completeness: helper throws a dedicated closeout error with sanitized, bounded issue details.

***

### Task T004 - Add closeout fixture variants

**Started**: 2026-06-20 22:57 **Completed**: 2026-06-20 22:58 **Duration**: 1 minute

**Notes**:

* Added closeout fixture exports for complete generated payloads, missing topic fields, wrong-shaped topic fields, missing report fields, wrong-shaped report fields, and allowed empty fallback shapes.
* Kept malformed variants as builder functions returning `unknown` so production fixture typing remains accurate.

**Files Changed**:

* `src/extensions/trend-finder/fixtures.ts` - added closeout fixture builders and exported required field lists.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T004 complete.

**BQC Fixes**:

* Contract alignment: malformed test payload builders return `unknown` instead of pretending invalid data satisfies `TrendFinderData`.

***

### Task T010 - Wire collector closeout before snapshots and handoff

**Started**: 2026-06-20 22:58 **Completed**: 2026-06-20 22:59 **Duration**: 1 minute

**Notes**:

* Added strict closeout assertion after browser diagnostics slimming and vector safety.
* The assertion runs before snapshot writes, archive retention, final Engine Replay trace rebuild, static Brief readiness logging, and collect return.
* Closeout failures are traced with sanitized issue strings and then thrown.

**Files Changed**:

* `scripts/extensions/trend-finder/collector.ts` - wired generated payload closeout assertion.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T010 complete.

**BQC Fixes**:

* Failure path completeness: generated payloads now fail before persistence or browser handoff when required derived branches are absent.
* Error information boundaries: trace details use helper-formatted sanitized issue strings.

***

### Task T011 - Wire collector validateData strict closeout

**Started**: 2026-06-20 22:58 **Completed**: 2026-06-20 22:59 **Duration**: 1 minute

**Notes**:

* Updated collector `validateData()` to reject raw generated payloads missing required derived fields before schema defaults can fill them.
* Existing schema validation still runs after strict closeout passes.

**Files Changed**:

* `scripts/extensions/trend-finder/collector.ts` - added strict closeout check to `validateData()`.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T011 complete.

**BQC Fixes**:

* Trust boundary enforcement: extension payload validation now checks raw generated shape at the collector boundary.

***

### Task T007 - Prepare static Brief export and QA error plumbing

**Started**: 2026-06-20 22:59 **Completed**: 2026-06-20 23:00 **Duration**: 1 minute

**Notes**:

* Added a static Brief QA issue code and mapper for required-derived-field closeout failures.
* Static export now maps closeout failures into blocking, sanitized error detail strings.

**Files Changed**:

* `scripts/extensions/trend-finder/static-brief-qa.ts` - added closeout QA issue mapping.
* `scripts/extensions/trend-finder/static-brief-export.ts` - mapped raw closeout failures to static export errors.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T007 complete.

**BQC Fixes**:

* Error information boundaries: static export closeout details reuse the sanitized helper formatter.

***

### Task T012 - Wire static Brief export closeout and duplicate prevention

**Started**: 2026-06-20 22:59 **Completed**: 2026-06-20 23:00 **Duration**: 1 minute

**Notes**:

* Static Brief export now runs required-derived-field closeout on raw Trend Finder data after input privacy scanning and before schema parsing, projection, rendering, QA, or output promotion.
* Added per-output-directory in-flight protection so concurrent export calls cannot race on the same output root.

**Files Changed**:

* `scripts/extensions/trend-finder/static-brief-export.ts` - added raw closeout gate and active export guard.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T012 complete.

**BQC Fixes**:

* Duplicate action prevention: concurrent exports to the same output directory now fail with `export_in_progress`.
* Failure path completeness: malformed generated payloads fail before HTML rendering or file promotion.

***

### Task T013 - Add static Brief QA issue handling for closeout failures

**Started**: 2026-06-20 22:59 **Completed**: 2026-06-20 23:00 **Duration**: 1 minute

**Notes**:

* Added `required_derived_field` as a blocking static Brief QA issue code and mapped issue sections to run narratives or top opportunities.
* Messages include only the sanitized closeout issue fields.

**Files Changed**:

* `scripts/extensions/trend-finder/static-brief-qa.ts` - added closeout issue code and mapper.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T013 complete.

**BQC Fixes**:

* Error information boundaries: QA closeout messages do not include topic names, evidence text, source content, prompts, paths, or provider output.

***

### Task T014 - Keep required derived branches visible in payload-size reporting

**Started**: 2026-06-20 23:00 **Completed**: 2026-06-20 23:00 **Duration**: 0 minutes

**Notes**:

* Verified `measure-payload-size.ts` already always includes `data.runNarratives`, `data.topics[].attentionPattern`, `data.topics[].receptionSignal`, `data.topics[].corroboration`, and `data.topics[].evidenceRationales`.
* No reporter output change was needed because the closeout gate adds no browser payload branch.

**Files Changed**:

* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T014 complete.

**BQC Fixes**:

* Contract alignment: preserved existing payload budget visibility for the required derived branches without adding unused report rows.

***

### Task T015 - Update Trend Finder pipeline docs

**Started**: 2026-06-20 23:00 **Completed**: 2026-06-20 23:01 **Duration**: 1 minute

**Notes**:

* Documented the generated payload closeout stage, required branches, strict closeout versus legacy schema defaults, and static export blocking behavior.

**Files Changed**:

* `docs/extensions/trend-finder-pipeline.md` - added closeout behavior to pipeline, release checks, static export, and implementation map.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T015 complete.

***

### Task T016 - Update Trend Finder surface docs

**Started**: 2026-06-20 23:00 **Completed**: 2026-06-20 23:01 **Duration**: 1 minute

**Notes**:

* Documented that live/static surfaces require generated derived fields before rendering and that legacy schema defaults remain separate from strict closeout.

**Files Changed**:

* `docs/extensions/trend-finder-ui-surfaces.md` - added required derived field closeout surface notes.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T016 complete.

***

### Task T017 - Add helper unit tests

**Started**: 2026-06-20 23:01 **Completed**: 2026-06-20 23:02 **Duration**: 1 minute

**Notes**:

* Added helper tests for complete payloads, allowed empty fallback shapes, missing topic fields, wrong-shaped topic fields, missing and wrong-shaped report branches, issue caps, deterministic ordering, safe formatting, and unsafe topic ID fallback.

**Files Changed**:

* `scripts/extensions/trend-finder/__tests__/required-derived-fields.test.ts` - added closeout helper coverage.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T017 complete.

**BQC Fixes**:

* Error information boundaries: tests assert closeout messages exclude topic names, evidence titles, URLs, local paths, prompts, provider-response markers, and unsafe topic IDs.

***

### Task T018 - Add collector and static Brief export closeout tests

**Started**: 2026-06-20 23:02 **Completed**: 2026-06-20 23:03 **Duration**: 1 minute

**Notes**:

* Added collector `validateData()` coverage for complete closeout payload success and missing field rejection with sanitized reasons.
* Added static Brief export coverage for blocking missing required fields before rendering/output promotion, preserving existing output, and complete payload dry-run success.

**Files Changed**:

* `scripts/extensions/trend-finder/__tests__/collector.test.ts` - added collector strict closeout validation test.
* `scripts/extensions/trend-finder/__tests__/static-brief-export.test.ts` - added static export closeout failure and success coverage.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T018 complete.

**BQC Fixes**:

* Failure path completeness: tests assert static export fails before output promotion.
* Error information boundaries: tests assert collector/export failures exclude raw source titles, evidence titles, URLs, local paths, prompts, and provider-response markers.

***

### Task T019 - Add schema/view-model and e2e regressions

**Started**: 2026-06-20 23:03 **Completed**: 2026-06-20 23:04 **Duration**: 1 minute

**Notes**:

* Added a legacy parse regression proving missing required closeout branches still default through normal schema parsing.
* Updated the static Brief e2e to assert complete payload projection includes QA pass, run narratives, and polarity/attention rows before existing privacy and overflow checks.

**Files Changed**:

* `src/extensions/trend-finder/__tests__/view-model.test.ts` - added legacy default regression for all required closeout branches.
* `tests/e2e/trend-finder-static-brief.spec.ts` - added complete-payload static Brief projection assertions.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T019 complete.

**BQC Fixes**:

* Contract alignment: tests preserve the distinction between defaultable legacy parsing and strict generated/export closeout.

***

### Task T020 - Run focused validation checks

**Started**: 2026-06-20 23:04 **Completed**: 2026-06-20 23:07 **Duration**: 3 minutes

**Notes**:

* Formatted touched code, docs, and session files with Prettier.
* Ran focused Vitest coverage for helper, collector, static Brief export, and view-model regressions.
* Ran application and script TypeScript checks.
* Ran static Brief Playwright e2e, payload-size reporting, private-artifact scan, whitespace check, and ASCII validation.

**Files Changed**:

* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/implementation-notes.md` - recorded final validation evidence.
* `.spec_system/specs/phase29-session08-required-derived-field-closeout-gate/tasks.md` - marked T020 and completion checklist complete.

**BQC Fixes**:

* Contract alignment: script typecheck caught an invalid test object inference, fixed by explicitly typing malformed test data as `Record<string, unknown>`.

***

## Validation Evidence

* `bun run test -- scripts/extensions/trend-finder/__tests__/required-derived-fields.test.ts scripts/extensions/trend-finder/__tests__/collector.test.ts scripts/extensions/trend-finder/__tests__/static-brief-export.test.ts src/extensions/trend-finder/__tests__/view-model.test.ts` - passed, 4 files / 111 tests.
* `bun run typecheck` - passed.
* `bun run typecheck:scripts` - passed after fixing the test-only type inference.
* `bun run test:e2e -- tests/e2e/trend-finder-static-brief.spec.ts` - passed, 1 Playwright test.
* `bun run scripts/extensions/trend-finder/measure-payload-size.ts --json` - passed; Trend Finder browser data payload reported at 457,150 bytes under the 1,048,576-byte boundary.
* `bun run runtime:check-private` - passed.
* `git diff --check` - passed.
* ASCII validation for 16 touched/session files - passed.


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