> 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/phase27-session02-deterministic-derived-signals-and-risk-flags/implementation_summary.md).

# Implementation Summary

**Session ID**: `phase27-session02-deterministic-derived-signals-and-risk-flags` **Completed**: 2026-06-12 **Duration**: 0.6 hours

***

## Overview

Session 02 added deterministic Trend Finder derived signals with no new AI or source calls: saturation, continuous hidden-gem score, healthy-source consensus, source role shares, builder signal share, and bounded risk flags. The work kept the weighted six-factor opportunity score unchanged, preserved legacy payload parsing through additive defaults, and surfaced the new signals across trend cards, source breakdowns, Hidden Gems, and Signal Workbench.

***

## Deliverables

### Files Created

| File                                                                                                          | Purpose                                    | Lines |
| ------------------------------------------------------------------------------------------------------------- | ------------------------------------------ | ----- |
| `.spec_system/specs/phase27-session02-deterministic-derived-signals-and-risk-flags/spec.md`                   | Session scope and implementation contract. | 354   |
| `.spec_system/specs/phase27-session02-deterministic-derived-signals-and-risk-flags/tasks.md`                  | 20-task checklist and completion tracker.  | 94    |
| `.spec_system/specs/phase27-session02-deterministic-derived-signals-and-risk-flags/implementation-notes.md`   | Task-by-task implementation record.        | 482   |
| `.spec_system/specs/phase27-session02-deterministic-derived-signals-and-risk-flags/security-compliance.md`    | Security and GDPR review.                  | 92    |
| `.spec_system/specs/phase27-session02-deterministic-derived-signals-and-risk-flags/validation.md`             | Validation report and quality gates.       | 253   |
| `scripts/lib/ai-runtime/risk-flags.ts`                                                                        | Deterministic per-topic risk flag helper.  | 148   |
| `scripts/lib/ai-runtime/__tests__/risk-flags.test.ts`                                                         | Risk flag unit tests and edge cases.       | 125   |
| `.spec_system/specs/phase27-session02-deterministic-derived-signals-and-risk-flags/IMPLEMENTATION_SUMMARY.md` | Session closeout summary.                  | 134   |

### Files Modified

| File                                                                   | Changes                                                                                      |
| ---------------------------------------------------------------------- | -------------------------------------------------------------------------------------------- |
| `.spec_system/PRD/phase_27/PRD_phase_27.md`                            | Marked Session 02 complete and updated phase progress.                                       |
| `.spec_system/state.json`                                              | Added Session 02 to completed sessions and history; cleared current session.                 |
| `package.json`                                                         | Bumped patch version from 0.1.304 to 0.1.305.                                                |
| `README.md`                                                            | Updated the displayed project version to 0.1.305.                                            |
| `scripts/extensions/trend-finder/collector.ts`                         | Preserved derived fields through collector attachment steps and trace output.                |
| `scripts/extensions/trend-finder/topics.ts`                            | Added topic normalization alias updates.                                                     |
| `scripts/lib/ai-runtime/scoring.ts`                                    | Added saturation, hidden-gem score, and risk flag derivation without changing score weights. |
| `scripts/lib/ai-runtime/source-breakdown.ts`                           | Added consensus ratio, role shares, and builder signal share.                                |
| `src/extensions/trend-finder/schema.ts`                                | Added additive derived signal fields, defaults, and risk flag enum.                          |
| `src/extensions/trend-finder/view-model.ts`                            | Added labels, bands, risk chips, unavailable copy, and Hidden Gems ordering.                 |
| `src/extensions/trend-finder/signal-workbench-model.ts`                | Added derived rows, filters, facets, search, and sort values.                                |
| `src/extensions/trend-finder/components/trend-card.tsx`                | Rendered derived metrics and bounded risk chips.                                             |
| `src/extensions/trend-finder/components/source-breakdown.tsx`          | Rendered consensus and role-share summaries.                                                 |
| `src/extensions/trend-finder/components/signal-workbench-controls.tsx` | Added saturation and risk filter controls.                                                   |
| `src/extensions/trend-finder/components/signal-workbench-table.tsx`    | Added compact derived signal columns and chips.                                              |
| `src/extensions/trend-finder/views/hidden-gems-view.tsx`               | Sorted and described Hidden Gems by continuous hidden-gem score.                             |
| `src/extensions/trend-finder/views/signal-workbench-view.tsx`          | Reset stale filters and sort state on run re-entry.                                          |
| `src/extensions/trend-finder/fixtures.ts`                              | Added filled, unavailable, and risk-flagged fixture coverage.                                |
| `scripts/lib/ai-runtime/__tests__/scoring.test.ts`                     | Covered saturation, hidden-gem score, and unchanged weighted scoring.                        |
| `scripts/lib/ai-runtime/__tests__/source-breakdown.test.ts`            | Covered consensus denominator, role shares, builder signal, and degraded sources.            |
| `src/extensions/trend-finder/__tests__/view-model.test.ts`             | Covered labels, unavailable states, risk chips, and Hidden Gems ordering.                    |
| `src/extensions/trend-finder/__tests__/signal-workbench-model.test.ts` | Covered Workbench projection, filters, facets, search, and sorting.                          |
| `src/lib/__tests__/trend-finder-schema.test.ts`                        | Covered legacy payload defaults and invalid risk flag rejection.                             |
| `src/lib/__tests__/trend-finder-dashboard.test.tsx`                    | Updated dashboard expectations for additive fields.                                          |
| `scripts/lib/__tests__/source-breakdown.test.ts`                       | Updated legacy source-breakdown expectations.                                                |
| `scripts/lib/ai-runtime/__tests__/historical-context.test.ts`          | Updated fixture expectations for additive defaults.                                          |
| `scripts/lib/ai-runtime/__tests__/snapshots.test.ts`                   | Updated fixture expectations for additive defaults.                                          |
| `scripts/lib/ai-runtime/__tests__/watchlist.test.ts`                   | Updated fixture expectations for additive defaults.                                          |

***

## Technical Decisions

1. **Additive nullable derived fields**: Unavailable ratios and scores use `null` defaults so the UI can avoid fake zero signals while legacy payloads continue to parse.
2. **Runtime-only deterministic math**: Derived signals are computed under the script/runtime boundary from existing evidence, source, source-local, and historical context; no new adapters, AI calls, or third-party transfers were added.
3. **Centralized UI projection**: Cards, Hidden Gems, source breakdown, and Workbench consume shared view-model helpers for labels, tones, risk chips, and ordering.

***

## Test Results

| Metric   | Value   |
| -------- | ------- |
| Tests    | 3334    |
| Passed   | 3334    |
| Coverage | Not run |

Commands validated:

* `bun run test` - passed, 268 files / 3334 tests.
* `bun run typecheck` - passed.
* `bun run typecheck:scripts` - passed.
* Focused Trend Finder/runtime tests - passed, 7 files / 164 tests.
* Signal Workbench view focused test - passed, 1 file / 6 tests.
* ASCII and CRLF scans - passed.

***

## Lessons Learned

1. Additive defaults remain the safest way to evolve browser payloads without breaking old generated data or fixtures.
2. Deterministic ordering is important for dense triage surfaces because new filters and columns can otherwise make results feel unstable.
3. Explicit unavailable labels are better than numeric placeholders for derived signals that depend on evidence or healthy-source denominators.

***

## Future Considerations

Items for future sessions:

1. Session 03 should reuse saturation and hidden-gem score when wiring data-driven radar positions, aliases, and watching state.
2. Session 04 persistence can use these derived fields as stable display inputs while adding daily series and Hugging Face deltas.
3. Continue payload-size checks as later Phase 27 sessions add arrays such as sparklines, story log rows, demand clusters, and trajectory data.

***

## Session Statistics

* **Tasks**: 20 completed
* **Files Created**: 8
* **Files Modified**: 28
* **Tests Added**: 11 test files added or updated
* **Blockers**: 0 resolved


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