> 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-session11-search-palette-and-deterministic-embeddings/implementation_summary.md).

# Implementation Summary

**Session ID**: `phase28-session11-search-palette-and-deterministic-embeddings` **Completed**: 2026-06-14 **Duration**: 1.6 hours

***

## Overview

Completed Phase 28 Session 11 by shipping the Trend Finder command palette and dependency-free feature-hash embeddings. The work added safe search projection over loaded payload text, browser and script vector helpers, hybrid lexical and cosine ranking, deterministic fallback clustering improvements, payload guards, documentation updates, and focused/full validation coverage.

***

## Deliverables

### Files Created

| File                                                                             | Purpose                                                                              | Lines |
| -------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------ | ----- |
| `src/lib/trend-text-vector-features.ts`                                          | Shared feature extraction, lexical scoring, vector contracts, and cosine math.       | 408   |
| `scripts/lib/ai-runtime/text-vectors.ts`                                         | Script-side SHA-256 feature-hash vectors, ranking, and similarity grouping.          | 198   |
| `src/extensions/trend-finder/text-vectors.ts`                                    | Browser Web Crypto vectors with timeout, stale-query, and lexical fallback handling. | 205   |
| `src/extensions/trend-finder/search-index.ts`                                    | Safe Trend Finder search document projection, scope filtering, and bounded ranking.  | 396   |
| `src/extensions/trend-finder/components/trend-search-palette.tsx`                | Keyboard command palette UI, result grouping, state rows, and navigation handling.   | 380   |
| `scripts/lib/ai-runtime/__tests__/text-vectors.test.ts`                          | Script vector determinism, normalization, cosine, grouping, and ranking tests.       | 78    |
| `src/lib/__tests__/trend-text-vector-features.test.ts`                           | Shared feature extraction, lexical scoring, and vector math tests.                   | 65    |
| `src/extensions/trend-finder/__tests__/search-index.test.ts`                     | Search index, scope, ranking, href, and no-vector-payload tests.                     | 71    |
| `src/extensions/trend-finder/components/__tests__/trend-search-palette.test.tsx` | Palette focus, scope, empty/offline/fallback, Enter selection, and navigation tests. | 90    |

### Files Modified

| File                                                              | Changes                                                                                         |
| ----------------------------------------------------------------- | ----------------------------------------------------------------------------------------------- |
| `scripts/extensions/trend-finder/theme-rollups.ts`                | Added similarity-assisted fallback grouping while preserving analyst labels.                    |
| `scripts/extensions/trend-finder/topics.ts`                       | Replaced source-only fallback clustering with similarity clusters over evidence titles.         |
| `scripts/extensions/trend-finder/collector.ts`                    | Added similarity trace summaries, fallback warnings, and vector-array publish guard.            |
| `src/extensions/trend-finder/client.tsx`                          | Mounted the palette and scoped Ctrl/Cmd+K plus slash shortcut handling.                         |
| `src/extensions/trend-finder/view-model.ts`                       | Added search-safe labels and Trend Finder href helpers.                                         |
| `src/extensions/trend-finder/fixtures.ts`                         | Added alias, evidence, source, and hidden-topic search coverage.                                |
| `src/extensions/trend-finder/signal-workbench-storage.ts`         | Adjusted browser storage lookup to satisfy script typecheck without runtime behavior drift.     |
| `scripts/extensions/trend-finder/__tests__/theme-rollups.test.ts` | Added similarity grouping, analyst precedence, and lexical fallback coverage.                   |
| `scripts/extensions/trend-finder/__tests__/collector.test.ts`     | Added no-vector browser payload assertion.                                                      |
| `scripts/extensions/trend-finder/__tests__/normalize.test.ts`     | Added fallback title-similarity topic clustering coverage.                                      |
| `src/lib/__tests__/trend-finder-schema.test.ts`                   | Added search projection private-string and vector-array payload-safety assertions.              |
| `docs/adr/0002-trend-finder-embedding-fallback-clustering.md`     | Recorded shipped feature-hash embedding decision and rejected model/vector database dependency. |
| `docs/extensions/trend-finder-ui-surfaces.md`                     | Documented palette behavior, scope filters, shortcut boundary, and browser-only ranking.        |
| `docs/extensions/trend-finder-runtime-and-provenance.md`          | Documented feature-hash clustering, transient vector boundary, and AI-mode non-regression.      |
| `.spec_system/state.json`                                         | Marked the session complete and cleared the current session pointer.                            |
| `.spec_system/PRD/phase_28/PRD_phase_28.md`                       | Updated progress, tracker, completed summary, next session, and success criteria.               |
| `package.json`                                                    | Bumped version from 0.1.328 to 0.1.329.                                                         |
| `README.md`                                                       | Synced the root version line to 0.1.329.                                                        |
| `docs/CHANGELOG.md`                                               | Added the Phase 28 Session 11 closeout entry.                                                   |

***

## Technical Decisions

1. **Dependency-free feature hashing**: Used SHA-256 feature hashing instead of adding a model dependency or vector database, preserving the no-new-runtime dependency boundary.
2. **Transient browser vectors only**: Kept vectors computed in memory from loaded payload text and rejected vector-shaped arrays before browser payload publication.
3. **Fallback-first ranking**: Kept lexical scoring as the guaranteed baseline and used cosine ranking only when vector generation succeeds.
4. **AI-mode non-regression**: Improved deterministic theme and topic fallback clustering without replacing higher-fidelity analyst clustering.

***

## Test Results

| Metric   | Value                   |
| -------- | ----------------------- |
| Tests    | 3608 full / 190 focused |
| Passed   | 3608 full / 190 focused |
| Coverage | Not generated           |

Validation also passed app and script typechecks, `git diff --check`, ASCII/LF checks, security review, and a focused browser smoke for palette open/navigation behavior.

***

## Lessons Learned

1. Keeping hashing environment-specific avoids Node imports leaking into the browser bundle while preserving one shared feature contract.
2. Search projection needs the same browser-safe boundary as static exports: sanitize strings first, then index.
3. Vector fallback states should be visible to the UI instead of hiding behind a perpetual loading state.

***

## Future Considerations

Items for future sessions:

1. Revisit similarity thresholds after more live Trend Finder payloads are available.
2. Keep Session 12 Brief export QA aligned with the new search projection leak checks.
3. Treat any future persisted vector or model-backed embedding path as a new ADR.

***

## Session Statistics

* **Tasks**: 25 completed
* **Files Created**: 9
* **Files Modified**: 19
* **Tests Added**: 8
* **Blockers**: 0 resolved


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