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# Implementation Summary

**Session ID**: `phase23-session03-projection-folding` **Package**: apps/web **Completed**: 2026-07-05 **Duration**: 0.5 hours

***

## Overview

Session 03 replaced the `suggestion_update` projection no-op with scanner camp reconciliation in the web game projection reducer. Current Quest Board scanner issue snapshots now fold through the Phase 23 pure reconciliation helper into aggregate Legion camps and safe sectors, while replay, mock persistence guards, links, rewards, camp damage, and unrelated projection state remain isolated.

***

## Deliverables

### Files Created

| File | Purpose                                                | Lines |
| ---- | ------------------------------------------------------ | ----- |
| None | This session created no application deliverable files. | 0     |

### Files Modified

| File                                    | Changes                                                                                                                                                                                                                                                      |
| --------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `apps/web/src/lib/gameProjection.ts`    | Imports `reconcileLegionCamps`, adds camp and sector record equality helpers, folds non-replay scanner snapshots into aggregate camps/sectors, updates `lastEventAt` only on aggregate changes, and finalizes alert focus through existing priority helpers. |
| `apps/web/tests/gameProjection.test.ts` | Adds scanner snapshot helpers plus focused tests for camp creation, HP/tier math, stable sectors, coalescing, entrenchment, membership reset, removals, replay no-op, mock in-memory folding, alert priority, field isolation, and privacy exclusions.       |

***

## Technical Decisions

1. **Reducer-only folding**: Kept `gameProjection.ts` as the single derived game-state authority and avoided new protocol events, storage keys, hosted state, rewards, camp damage, mission links, or UI behavior.
2. **Replay-first guard**: Replayed `suggestion_update` events return the original projection before reconciliation so reconnect/replay paths stay camp-inert.
3. **Aggregate equality checks**: Added reducer-local camp and sector record comparisons so no-op snapshots preserve projection identity and do not advance `lastEventAt`.
4. **Existing alert composition**: Routed changed scanner camps through `finalizeProjectionUpdate` so `newCamp` focus stays below flares, gates, siege, rams, and skirmishers.

***

## Test Results

| Metric        | Value                  |
| ------------- | ---------------------- |
| Focused Tests | 31 passed              |
| Root Tests    | 3227 passed, 1 skipped |
| Web Typecheck | PASS                   |
| Coverage      | Not reported           |

***

## Lessons Learned

1. The pure reconciliation helper reports enough aggregate state for reducer folding, but the reducer still needs full record equality because removals and sector-only changes are meaningful.
2. Existing mock-mode behavior belongs in persistence guards, not in reducer rejection; mock snapshots can fold in memory without being persisted.
3. The old no-progress snapshot test needed narrowing: scanner snapshots remain no-progress for rewards and links, but now honestly mutate aggregate camps.

***

## Future Considerations

Items for future sessions:

1. Session 04 should prove persistence, replay, reset, mock-mode, and browser-local erasure boundaries for the newly folded camp state.
2. Session 05 should connect camp inspection and dry Banish behavior through existing Quest Board issue cards and dismissal actions.
3. Session 06 should render the reconciled camps accessibly on the battlefield without creating fake danger or new combat mechanics.

***

## Session Statistics

* **Tasks**: 20 completed
* **Files Created**: 0 application deliverables
* **Files Modified**: 2 application deliverables
* **Tests Added**: 5 focused reducer test cases plus helper coverage
* **Blockers**: 0 resolved


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