# Context Manager Task 4 Implementer Report

## Status
- Done
- Implemented packet building in `.pi/agent/extensions/context-manager/src/packet.ts`
- Implemented context pruning in `.pi/agent/extensions/context-manager/src/prune.ts`
- Added focused tests for both modules

## Changes
- Added `buildContextPacket()` with ordered section emission, priority sorting, and packet token-cap enforcement.
- Added `pruneContextMessages()` with recent-turn preservation and bulky old tool-result pruning.
- Reused existing policy and ledger types from `src/config.ts` and `src/ledger.ts`.
- Kept the implementation scoped to Task 4 only.

## Tests
- Verified red state first:
  - `cd .pi/agent/extensions/context-manager && npx tsx --test src/packet.test.ts src/prune.test.ts`
  - Result: failed with `ERR_MODULE_NOT_FOUND` because `src/packet.ts` and `src/prune.ts` did not exist yet
- Verified green state after implementation:
  - `cd .pi/agent/extensions/context-manager && npx tsx --test src/packet.test.ts src/prune.test.ts`
- Ran full extension test suite:
  - `cd .pi/agent/extensions/context-manager && npm test`

## Files Changed
- Created `.pi/agent/extensions/context-manager/src/packet.ts`
- Created `.pi/agent/extensions/context-manager/src/prune.ts`
- Created `.pi/agent/extensions/context-manager/src/packet.test.ts`
- Created `.pi/agent/extensions/context-manager/src/prune.test.ts`
- Created `.pi/reviews/context-manager-task4-implementer-report.md`

## Self-Review Findings
- Section ordering and token-cap behavior are covered by the packet test.
- Pruning behavior is covered by the prune test and preserves the latest user turn.
- No unrelated files in the extension package were modified.

## Concerns
- No known concerns.