> 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/phase24-session02-delta-aware-enrichment-spend-accounting/tasks.md).

# Task Checklist

**Session ID**: `phase24-session02-delta-aware-enrichment-spend-accounting` **Total Tasks**: 25 **Estimated Duration**: 3.5-4 hours **Created**: 2026-06-07

***

## Legend

* `[x]` = Completed
* `[ ]` = Pending
* `[P]` = Parallelizable (can run with other \[P] tasks)
* `[SNNMM]` = Session reference (NN=phase number, MM=session number)
* `TNNN` = Task ID

***

## Progress Summary

| Category       | Total  | Done   | Remaining |
| -------------- | ------ | ------ | --------- |
| Setup          | 3      | 3      | 0         |
| Foundation     | 6      | 6      | 0         |
| Implementation | 12     | 12     | 0         |
| Testing        | 4      | 4      | 0         |
| **Total**      | **25** | **25** | **0**     |

***

## Setup (3 tasks)

Initial verification and environment preparation.

* [x] T001 \[S2402] Verify stable evidence ID, source-local, and Trend Finder schema semantics (`src/extensions/trend-finder/schema.ts`)
* [x] T002 \[S2402] Confirm private cache root and ignored artifact conventions (`.gitignore`)
* [x] T003 \[S2402] Confirm current Apify and Google Trends charge cap metadata (`scripts/lib/apify/types.ts`)

***

## Foundation (6 tasks)

Core contracts and base implementations.

* [x] T004 \[S2402] \[P] Create private enrichment cache helper with schema-validated entries, path containment, atomic writes, and idempotency protection (`scripts/extensions/trend-finder/enrichment-cache.ts`)
* [x] T005 \[S2402] \[P] Create spend accounting helper with bounded currency math, exact/estimated states, cadence-unavailable fallback, and raw billing redaction (`scripts/extensions/trend-finder/spend-accounting.ts`)
* [x] T006 \[S2402] Extend source adapter contracts for enrichment cache and spend summaries with types matching declared contract and exhaustive enum handling (`scripts/extensions/trend-finder/sources/types.ts`)
* [x] T007 \[S2402] Extend browser Trend Finder schema with additive cache and spend summaries with safe defaults for legacy payloads (`src/extensions/trend-finder/schema.ts`)
* [x] T008 \[S2402] Extend Engine Trace browser contract with bounded cache and spend summaries with deterministic ordering (`src/extensions/trend-finder/engine-trace.ts`)
* [x] T009 \[S2402] Extend Apify run result types for safe usage and charge cap summaries with raw provenance excluded from browser contracts (`scripts/lib/apify/types.ts`)

***

## Implementation (12 tasks)

Main feature implementation.

* [x] T010 \[S2402] Capture Apify `usageTotalUsd` and configured charge caps in run results with explicit failure-path handling (`scripts/lib/apify/actors.ts`)
* [x] T011 \[S2402] Emit per-source Apify spend summaries with timeout, retry/backoff, and failure-path handling preserved (`scripts/extensions/trend-finder/sources/apify-adapter.ts`)
* [x] T012 \[S2402] Emit Google Trends demand spend summaries with exact/estimated labels, max charge caps, and missing-token fallback behavior (`scripts/extensions/trend-finder/sources/google-trends-demand.ts`)
* [x] T013 \[S2402] Implement cheap-first enrichment cache selection and merge flow with idempotency protection, transaction boundaries, and compensation on failure (`scripts/extensions/trend-finder/collector.ts`)
* [x] T014 \[S2402] Implement enrichment cache pruning from the active evidence keep set with cleanup on scope exit for all acquired resources (`scripts/extensions/trend-finder/collector.ts`)
* [x] T015 \[S2402] Emit sanitized cache and spend trace events with schema-validated input and explicit error mapping (`scripts/extensions/trend-finder/engine-trace.ts`)
* [x] T016 \[S2402] Project cache and spend summaries into Engine Replay metrics with explicit loading, empty, error, and offline states (`src/extensions/trend-finder/engine-replay-model.ts`)
* [x] T017 \[S2402] Add source spend and enrichment cache state to Sources view with platform-appropriate accessibility labels, focus management, and input support (`src/extensions/trend-finder/views/sources-view.tsx`)
* [x] T018 \[S2402] Update Trend Finder fixtures and fallback data for cache hits, skipped enrichment, pruned entries, and spend estimates (`src/extensions/trend-finder/fixtures.ts`)
* [x] T019 \[S2402] Update committed live-data fallback shape for additive cache and spend fields (`src/data/live-data.example.json`)
* [x] T020 \[S2402] \[P] Update pipeline docs for enrichment cache, retention, pruning, and spend accounting (`docs/extensions/trend-finder-pipeline.md`)
* [x] T021 \[S2402] \[P] Update source and runtime provenance docs for source spend, cache state, exact/estimated labels, and cadence-unavailable state (`docs/extensions/trend-finder-sources.md`, `docs/extensions/trend-finder-runtime-and-provenance.md`)

***

## Testing (4 tasks)

Verification and quality assurance.

* [x] T022 \[S2402] \[P] Write enrichment cache unit tests for keys, validation, hits, misses, stale fingerprints, atomic writes, and pruning (`scripts/extensions/trend-finder/__tests__/enrichment-cache.test.ts`)
* [x] T023 \[S2402] \[P] Write spend accounting tests for actual usage, estimates, caps, cadence-unavailable state, and redaction (`scripts/extensions/trend-finder/__tests__/spend-accounting.test.ts`)
* [x] T024 \[S2402] Extend adapter, collector, schema, and Engine Replay tests for cache/spend summaries and legacy payload defaults (`scripts/extensions/trend-finder/__tests__/collector.test.ts`)
* [x] T025 \[S2402] Run focused Trend Finder tests and ASCII checks (`package.json`)

***

## Completion Checklist

Before marking session complete:

* [x] All tasks marked `[x]`
* [x] All tests passing
* [x] All files ASCII-encoded
* [x] implementation-notes.md updated
* [x] Ready for the validate workflow step

***

## Next Steps

Run the implement workflow step to begin AI-led implementation.


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