> 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/phase28-session01-cross-source-signal-identity-and-dedup/implementation_summary.md).

# Implementation Summary

**Session ID**: `phase28-session01-cross-source-signal-identity-and-dedup` **Completed**: 2026-06-14 **Duration**: 0.4 hours

***

## Overview

Completed Phase 28 Session 01 by adding a deterministic signal identity layer to Trend Finder. The session normalizes evidence URLs, derives content hashes and source-scoped fingerprints, drops exact same-source duplicates, preserves cross-source syndicated evidence rows, and uses grouped story inputs for scoring-sensitive volume, momentum, and diversity calculations. Browser and engine trace payloads expose only bounded aggregate counters.

***

## Deliverables

### Files Created

| File                                                                                                    | Purpose                                                     | Lines |
| ------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------- | ----- |
| `.spec_system/specs/phase28-session01-cross-source-signal-identity-and-dedup/spec.md`                   | Session specification.                                      | 329   |
| `.spec_system/specs/phase28-session01-cross-source-signal-identity-and-dedup/tasks.md`                  | Completed task checklist.                                   | 97    |
| `.spec_system/specs/phase28-session01-cross-source-signal-identity-and-dedup/implementation-notes.md`   | Task-by-task implementation and verification notes.         | 641   |
| `.spec_system/specs/phase28-session01-cross-source-signal-identity-and-dedup/security-compliance.md`    | Session security and GDPR report.                           | 83    |
| `.spec_system/specs/phase28-session01-cross-source-signal-identity-and-dedup/validation.md`             | Independent validation report.                              | 248   |
| `.spec_system/specs/phase28-session01-cross-source-signal-identity-and-dedup/IMPLEMENTATION_SUMMARY.md` | Updateprd closeout summary.                                 | \~95  |
| `scripts/extensions/trend-finder/sources/signal-identity.ts`                                            | URL normalization, hashing, dedup, and syndication helpers. | 532   |
| `scripts/extensions/trend-finder/sources/__tests__/signal-identity.test.ts`                             | Identity helper regression tests.                           | 162   |

### Files Modified

| File                                                             | Changes                                                                                                         |
| ---------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- |
| `.spec_system/state.json`                                        | Marked Session 01 complete, cleared current session, set Phase 28 in progress, and appended completion history. |
| `.spec_system/PRD/phase_28/PRD_phase_28.md`                      | Marked Session 01 complete, added completion date, and updated progress to 1/15.                                |
| `.gitignore`                                                     | Ignored accidental repo-local `~/` private runtime mirrors.                                                     |
| `README.md`                                                      | Synced visible project version to `0.1.319`.                                                                    |
| `docs/CHANGELOG.md`                                              | Added the Phase 28 Session 01 closeout entry.                                                                   |
| `package.json`                                                   | Bumped project version from `0.1.318` to `0.1.319`.                                                             |
| `scripts/extensions/trend-finder/collector.ts`                   | Wired identity metadata, duplicate filtering, warnings, and sanitized trace summaries.                          |
| `scripts/extensions/trend-finder/engine-trace.ts`                | Mapped identity trace events into aggregate replay evidence counters.                                           |
| `scripts/extensions/trend-finder/__tests__/collector.test.ts`    | Added dedup, high duplicate-rate, syndication, and browser-safe metadata tests.                                 |
| `scripts/extensions/trend-finder/__tests__/engine-trace.test.ts` | Added sanitized duplicate and syndicated group counter tests.                                                   |
| `scripts/lib/ai-runtime/trend-analyst.ts`                        | Added optional script-only identity and syndication metadata.                                                   |
| `scripts/lib/ai-runtime/scoring.ts`                              | Added syndicated story grouping for scoring-sensitive inputs while preserving display evidence.                 |
| `scripts/lib/ai-runtime/__tests__/scoring.test.ts`               | Added syndicated scoring projection regression coverage.                                                        |
| `src/extensions/trend-finder/engine-trace.ts`                    | Added aggregate duplicate and syndication evidence-count schema fields.                                         |
| `src/extensions/trend-finder/schema.ts`                          | Added additive bounded syndication count defaults for browser payloads.                                         |

***

## Technical Decisions

1. **Script-only identity metadata**: Raw normalized URLs, hashes, and source fingerprints remain out of browser payloads and engine replay output.
2. **Dedup before analyst input**: Same-source duplicates are dropped before both browser and analyst evidence paths so collection, analysis, and traces agree.
3. **Grouped scoring, full evidence display**: Syndicated story groups count once for scoring-sensitive volume, momentum, and diversity inputs while all legitimate per-source evidence rows remain available for links, source breakdowns, lifecycle, and role coverage.
4. **Additive schema defaults**: New counters default cleanly for legacy payloads and traces.

***

## Test Results

| Metric   | Value         |
| -------- | ------------- |
| Tests    | 3481          |
| Passed   | 3481          |
| Coverage | Not collected |

Validation passed with `bun run test`, `bun run typecheck`, `bun run typecheck:scripts`, `bun run lint`, scoped Prettier checks, ASCII/LF checks, and `git diff --check`.

***

## Lessons Learned

1. Cross-source syndication must be separated from same-source duplication so source coverage is preserved without inflating scoring inputs.
2. Aggregate-only trace counters are enough for replay proof and future collection-health work without exposing identity artifacts.
3. Legacy schema defaults are the lowest-risk way to add counters across the generated payload and replay surfaces.

***

## Future Considerations

Items for future sessions:

1. Session 02 should consume the duplicate and syndication counters for per-signal quality and collection-health rollups.
2. Keep raw URL, content hash, and fingerprint values script-only unless a later spec explicitly defines a safe operator-facing need.
3. Reuse the grouped scoring projection when later aging, saturation, and action-verdict work depends on evidence volume or source diversity.

***

## Session Statistics

* **Tasks**: 23 completed
* **Files Created**: 8
* **Files Modified**: 15
* **Tests Added**: 4 focused coverage areas
* **Blockers**: 0 resolved


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