> 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/archive/phases/phase_22/session_03_legion_enemy_reducer.md).

# Session 03: Legion Enemy Reducer

**Session ID**: `phase22-session03-legion-enemy-reducer` **Package**: apps/web **Status**: Not Started **Estimated Tasks**: \~12-25 **Estimated Duration**: 2-4 hours

***

## Objective

Implement Phase 22 live-enemy reducer cases without creating rewards, combat strikes, or new rendering state.

***

## Scope

### In Scope (MVP)

* Fold `test_failure`, `build_error`, `build_fix`, `ts_errors`, and `lint_error` into the serializable `legion` aggregate.
* Fold `task_stalled`, `task_near_stall`, and task escalation events into a single siege state with stable stalled-task refs.
* Fold failed `tool_result` events into per-hero wraith stacks with the Phase 22 cap and no board-level multiplication.
* Recompute `alertFocus` after lower-priority enemy state changes so siege, ram, skirmisher, and new-camp priorities promote only when higher-priority sources are absent.
* Add reducer tests for enemy upsert/clear behavior, wraith cap behavior, replay no-accumulation behavior, and focus promotion from enemy state.

### Out of Scope

* Follow the explicit out-of-scope and deferred-work boundaries in the Dependencies / Notes section below.
* Do not add rendering, audio, hosted persistence, protocol changes, or a second game state authority unless this session explicitly lists that work as in scope.

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## Dependencies / Notes

* Depends on Session 02.
* Failed tool-result stacking is allowed as enemy state, but replay mode must not farm repeated stacks.
* Out of scope: camp coalescing, camp kills, XP, loot, essence, combat strike queues, SFX, animation pulses, and rendering.

***

## Prerequisites

* [ ] Session 02 completed and validated.

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## Deliverables

1. Tested Legion reducer coverage for Phase 22's live error and stalled-task signals.
2. Projection-owned enemy attention that remains aggregate state, not animation state or score.

***

## Success Criteria

* [ ] Build, test, type, lint, stalled-task, and failed-tool events mutate only the documented Legion aggregate fields.
* [ ] Replay mode cannot increase progress-like enemy counters that would later become rewards.
* [ ] Lower-priority `alertFocus` sources appear only when flare and gate attention are absent.
* [ ] Serialized projection state remains bounded and contains no strike queue, toast queue, audio cue, or animation pulse.


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