> 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-session05-per-evidence-rationale/implementation_summary.md).

# Implementation Summary

**Session ID**: `phase29-session05-per-evidence-rationale` **Completed**: 2026-06-20 **Duration**: 0.5 hours

***

## Overview

Completed Phase 29 Session 05 by adding bounded per-evidence rationale support for Trend Finder topic evidence links. AI rationale output is validated against known cited evidence IDs and cited-row metadata, deterministic fallback copy covers no-AI paths, and weak unjustified links are omitted from topic rendering without deleting raw normalized evidence rows.

***

## Deliverables

### Files Created

| File                                                                                  | Purpose                                                                                          | Lines |
| ------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------ | ----- |
| `scripts/lib/ai-runtime/evidence-rationale.ts`                                        | Bounded rationale contract, fallback builder, grounding checks, and weak-link omission reasons.  | 517   |
| `scripts/lib/ai-runtime/__tests__/evidence-rationale.test.ts`                         | Unit coverage for fallback rationales, weak-link omission, bounded text, and grounding behavior. | 170   |
| `.spec_system/specs/phase29-session05-per-evidence-rationale/spec.md`                 | Session implementation specification.                                                            | 292   |
| `.spec_system/specs/phase29-session05-per-evidence-rationale/tasks.md`                | Completed 22-task checklist.                                                                     | 96    |
| `.spec_system/specs/phase29-session05-per-evidence-rationale/implementation-notes.md` | Task-by-task implementation notes and verification commands.                                     | 484   |
| `.spec_system/specs/phase29-session05-per-evidence-rationale/security-compliance.md`  | Session security and GDPR review.                                                                | 89    |
| `.spec_system/specs/phase29-session05-per-evidence-rationale/validation.md`           | PASS validation report.                                                                          | 237   |

### Files Modified

| File                                                                      | Changes                                                                                               |
| ------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------- |
| `.spec_system/state.json`                                                 | Marked Session 05 completed, cleared current session, and appended completion history.                |
| `.spec_system/PRD/phase_29/PRD_phase_29.md`                               | Updated Phase 29 progress to 5/18 and advanced upcoming work to Session 06.                           |
| `.spec_system/PRD/phase_29/session_05_per_evidence_rationale.md`          | Marked the session stub complete and checked completed criteria.                                      |
| `package.json`                                                            | Bumped version from `0.1.349` to `0.1.350`.                                                           |
| `README.md`                                                               | Synced visible version line to `0.1.350`.                                                             |
| `docs/CHANGELOG.md`                                                       | Added the Session 05 closeout entry.                                                                  |
| `scripts/lib/ai-runtime/trend-analyst.ts`                                 | Added analyst rationale schema and validation for known, cited, grounded evidence IDs.                |
| `scripts/extensions/trend-finder/collector.ts`                            | Merged AI/fallback rationales and omitted unjustified weak topic links while preserving raw evidence. |
| `scripts/extensions/trend-finder/topics.ts`                               | Added fallback rationale assignment for deterministic topic builders.                                 |
| `src/extensions/trend-finder/schema.ts`                                   | Added rationale constants, defaults, and legacy-safe parsing.                                         |
| `src/extensions/trend-finder/view-model.ts`                               | Projected rationale text, tone, and accessibility labels onto evidence links.                         |
| `src/extensions/trend-finder/components/evidence-links.tsx`               | Rendered compact rationale copy in live Evidence to verify cards.                                     |
| `scripts/extensions/trend-finder/static-brief-export.ts`                  | Projected bounded rationale fields into static Brief evidence rows.                                   |
| `scripts/extensions/trend-finder/static-brief-renderer.ts`                | Rendered escaped rationale markup in static Brief evidence cards.                                     |
| `scripts/extensions/trend-finder/measure-payload-size.ts`                 | Included rationale maps in payload-size reporting.                                                    |
| `src/extensions/trend-finder/fixtures.ts`                                 | Added AI, fallback, and omitted weak-evidence fixture examples.                                       |
| `scripts/lib/ai-runtime/__tests__/trend-analyst.test.ts`                  | Covered accepted grounded rationales and fabricated or unknown rationale rejection.                   |
| `scripts/extensions/trend-finder/__tests__/collector.test.ts`             | Covered topic-link omission with raw evidence preservation.                                           |
| `src/lib/__tests__/trend-finder-schema.test.ts`                           | Covered rationale schema defaults and invalid payload fallback behavior.                              |
| `src/extensions/trend-finder/__tests__/view-model.test.ts`                | Covered evidence-link rationale projection and missing-rationale behavior.                            |
| `src/extensions/trend-finder/components/__tests__/trend-card.test.tsx`    | Covered rendered rationale copy and accessible text.                                                  |
| `scripts/extensions/trend-finder/__tests__/static-brief-export.test.ts`   | Covered rationale projection and private/raw field exclusion.                                         |
| `scripts/extensions/trend-finder/__tests__/static-brief-renderer.test.ts` | Covered escaped rationale rendering and no raw/private leakage.                                       |

***

## Technical Decisions

1. **Validate AI rationales at the runtime boundary**: Analyst rationale text is rejected before scoring or display if it references unknown evidence, uncited evidence, unsafe text, or unsupported cited-row claims.
2. **Prefer deterministic fallback for gaps**: Valid AI rationale text wins, but the deterministic builder fills safe no-AI paths from already-collected relevance, quality, source-role, entity, metric, and topic cues.
3. **Project omissions instead of mutating raw evidence**: Weak unjustified evidence is removed from topic evidence links while raw normalized evidence remains available for audit and diagnostics.

***

## Test Results

| Metric   | Value         |
| -------- | ------------- |
| Tests    | 3748          |
| Passed   | 3748          |
| Coverage | Not collected |

Validation commands:

* `bun run test` - PASS, 318 test files and 3748 tests.
* `bun run typecheck` - PASS.
* `bun run typecheck:scripts` - PASS.
* `bun run scripts/extensions/trend-finder/measure-payload-size.ts src/data/live-data.example.json --threshold-kb=0 --json` - PASS, 14138 bytes for Trend Finder data.

***

## Lessons Learned

1. Rationale copy needs the same evidence-ID and invented-metadata guardrails as topic-level analyst output because it is browser-visible trust material.
2. Weak evidence omission is safer as a projection concern than as a raw evidence mutation because the normalized collection remains the audit trail.
3. Payload reporting should surface new derived maps even when a fixture has no records so future budget regressions are easier to spot.

***

## Future Considerations

Items for future sessions:

1. Reuse the evidence-ID grounding discipline for Session 06 cross-topic substrate narratives.
2. Keep static Brief and Engine Replay privacy scans focused on rationale text as more derived narrative fields are added.
3. Watch payload growth as later Phase 29 sessions add more per-topic derived fields.

***

## Session Statistics

* **Tasks**: 22 completed
* **Files Created**: 7
* **Files Modified**: 24
* **Tests Added**: 1 new helper suite plus expanded analyst, collector, schema, view-model, component, export, and renderer suites
* **Blockers**: 0 resolved


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://ai-os-and-trend-finder.gitbook.io/ai-os-and-trend-finder-docs/.spec_system/archive/sessions/phase29-session05-per-evidence-rationale/implementation_summary.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.