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# Session 02: Hero Attention Reducer

**Session ID**: `phase22-session02-hero-attention-reducer` **Package**: apps/web **Status**: Not Started **Estimated Tasks**: \~12-25 **Estimated Duration**: 2-4 hours

***

## Objective

Implement the hero lifecycle, player-attention, and gate portions of the pure reducer with one deterministic `alertFocus` authority.

***

## Scope

### In Scope (MVP)

* Implement `reduceGameProjection(state, event, ctx)` as a pure no-mutation reducer with injected `now`.
* Implement unknown-event same-reference behavior and explicit snapshot-vs-accumulation helper semantics.
* Fold hero lifecycle events: `internal_hero_spawn`, `roster_update`, and `hero_dismissed` without deleting earned aggregates or copying roster source-of-truth data.
* Fold `awaiting_input` and `input_received` with flare state, flare ceremony counters, swift-command timing, and replay-safe accumulation behavior.
* Fold gate attention from `permission_request`, `permission_response`, `guarded_action_update`, and `command_center_permission_update`, or explicitly defer any unsupported gate source with tests and a code comment.
* Implement `recomputeAlertFocus(state)` with the priority ladder `flare > gate > siege > ram > skirmisher > newCamp > null`.
* Add reducer tests for purity, hero snapshot reconciliation, alert priority promotion, flare clearing, gate clearing, and replay-safe swift-command behavior.

### 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 01.
* Any persisted pending refs needed to promote lower-priority alerts must be serializable aggregate state and intentionally documented in `GameProjection`; they must not be animation or toast state.
* Legacy permissions, guarded actions, and Command Center permissions should enter one gate tier; if a source cannot be folded safely in this session, leave a narrow deferred case with tests.
* Out of scope: Legion enemy reducers, camp linkage, XP, levels, title grants, relics, essence income, building XP, War Tide gains/losses, council objectives, nemesis promotion, fog, territory changes, and Dawn Report diffs.

***

## Prerequisites

* [ ] Session 01 completed and validated.

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## Deliverables

1. Tested pure reducer cases for hero lifecycle and attention authority.
2. A single projection-owned focus computation that later components can read instead of recomputing pulse priority.

***

## Success Criteria

* [ ] `reduceGameProjection` never mutates its inputs and returns the original reference for ignored events.
* [ ] Hero and attention snapshot events do not mint XP, essence, banners, kills, titles, War Tide progress, or other progress numbers.
* [ ] Replay mode can clear or reconcile attention but cannot accumulate swift-command counters or other progress-like values.
* [ ] Clearing a higher-priority focus promotes the next eligible focus and never leaves multiple simultaneous pulse authorities.


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