> For the complete documentation index, see [llms.txt](https://faction-os.gitbook.io/faction-os-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://faction-os.gitbook.io/faction-os-docs/.spec_system/specs/phase24-session01-pure-strike-and-combo-model/implementation_summary.md).

# Implementation Summary

**Session ID**: `phase24-session01-pure-strike-and-combo-model` **Package**: apps/web **Completed**: 2026-07-08 **Duration**: \~1 hour

***

## Overview

Built the pure combat playback model for Phase 24 (Legion II - Live Tier and Combat Playback). `apps/web/src/lib/combatPlayback.ts` provides the side-effect-free vocabulary the rest of the phase renders: deterministic strike classification from tool events (hammer/fire/scout/peon/generic plus tool-result counterattacks), combo merging that escalates instead of repeating (section 14.4), stage-prop milestones for long sieges, pure per-category SFX rate-limit decisions, and privacy-bounded strike labels that reuse the Phase 23 Legion sanitizers. All tunables are named exported constants for the design Phase 12 sweep.

***

## Deliverables

### Files Created

| File                                    | Purpose                                                            | Lines |
| --------------------------------------- | ------------------------------------------------------------------ | ----- |
| `apps/web/src/lib/combatPlayback.ts`    | Pure strike/combo/stage-prop/rate-limit/label model                | \~300 |
| `apps/web/tests/combatPlayback.test.ts` | 27 focused tests incl. 45-minute stream simulation and purity scan | \~350 |

### Files Modified

| File   | Changes                     |
| ------ | --------------------------- |
| (none) | Session was purely additive |

***

## Technical Decisions

1. **`shouldPlayCue(historyMs, nowMs)` drops the category parameter**: histories are caller-keyed per category, so category independence is structural; an unused parameter would imply cross-category coordination that does not exist.
2. **Out-of-order timestamps clamp forward**: `advanceComboState` never lets stages regress under WebSocket/replay reordering; the ordering contract is documented on the function.
3. **Only allowed cue plays are recorded**: rate-limit history stays bounded by the per-minute limit even under event storms.
4. **Labels route through `legionCamps.ts` sanitizers**: strike tooltips inherit the proven absolute-root scoping, sensitive-segment redaction, and ASCII normalization instead of a second sanitizer.

***

## Test Results

| Metric                           | Value                          |
| -------------------------------- | ------------------------------ |
| New focused tests                | 27 / 27 passed                 |
| Full web project                 | 2213 / 2213 passed (137 files) |
| Typecheck / Biome / format:check | clean                          |

***

## Lessons Learned

1. The full web suite must run from the repo root (`npx vitest run --project web`); invoking vitest inside `apps/web` bypasses the root config and its happy-dom environment, producing \~980 false failures.
2. Purity-contract source scans should strip comments before matching, or prose like "the trailing window." trips code-pattern regexes.

***

## Future Considerations

1. Session 02 should consume `comboKeyFor` and the link-expiry vocabulary when recording pending links.
2. Sessions 03/04 consume `classifyStrike`, `strikeEmissionsFor`, `stagePropsForElapsed`, and `STRIKE_MAX_DURATION_MS`; Session 06 consumes `shouldPlayCue` for world-cue categories.
3. `COMBO_WINDOW_MS` (4s), `COMBO_MAX_STAGE` (3), milestone spacing, and `SFX_RATE_LIMIT_PER_MINUTE` (6) are first-guess tuning values; design Phase 12 owns their playtest calibration.

***

## Session Statistics

* **Tasks**: 18 completed
* **Files Created**: 2
* **Files Modified**: 0
* **Tests Added**: 27
* **Blockers**: 0 resolved


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