> 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/phases/phase_29/session_08_required_derived_field_closeout_gate.md).

# Session 08: Required-Derived-Field Closeout Gate

**Session ID**: `phase29-session08-required-derived-field-closeout-gate` **Status**: Not Started **Estimated Tasks**: \~12-25 **Estimated Duration**: 2-4 hours

***

## Objective

Prevent blank or misleading surfaces by failing loudly when ranked topics lack the derived fields their surfaces expect. Maps the Tier 3 staleness/field gate idea.

***

## Scope

### In Scope (MVP)

* Add a closeout assertion after topic projection and before browser/static export.
* Gate only fields that have schema defaults and deterministic fallback support. Where Sessions 02-06 have shipped, include `attentionPattern`, `receptionSignal`, `corroboration`, `evidenceRationale`, and run narratives as applicable.
* Emit sanitized validation issues that identify the missing field and topic ID, not raw source content.

### Out of Scope

* Gating fields without schema defaults or deterministic fallback.
* Exposing raw source content in validation issues.

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## Prerequisites

* [ ] Sessions 02-06 complete (derived fields exist with defaults and fallback).

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## Deliverables

1. Closeout assertion before browser/static export.
2. Sanitized field/topic-ID validation issues.
3. Unit/e2e tests for missing-field failure and legacy-payload safety.

***

## Success Criteria

* [ ] A fixture topic missing a required derived field fails the closeout check before rendering.
* [ ] A legacy payload relying on schema defaults still parses safely.
* [ ] Validation issues name the field and topic ID without raw content.
* [ ] Payload budget and privacy scans remain green.

***

## Key Files

* `scripts/extensions/trend-finder/collector.ts`
* `src/extensions/trend-finder/schema.ts`
* `scripts/extensions/trend-finder/static-brief-qa.ts`
* `scripts/extensions/trend-finder/measure-payload-size.ts`
* `tests/e2e/trend-finder-static-brief.spec.ts`
* `tests/e2e/trend-finder-engine-replay.spec.ts`

***

## Comparison Notes (folded from comparison plan)

**Effort:** Low-Medium. **Boundary risk:** None. Tier 3 polish. **Depends on Sessions 02-06** (the derived fields it gates must exist first).

**Staleness/field gate.** In TrendingAI a blocking check ensures every confirmed feature has the expected sentiment row before render. Trend Finder adoption: add a closeout assertion that ranked topics have required derived fields before browser/static export. Gate only fields that have schema defaults and deterministic fallback support - when Sessions 02-06 have shipped, include `attentionPattern`, `receptionSignal`, `corroboration`, `evidenceRationale`, and run narratives as applicable.

**TrendingAI source pointers.** `scripts/validate-synthesis.ts`, `.claude/skills/TrendingAI/Workflows/Run.md`.


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