#4329 docs: slim proposed event journal ADR

Summary

Slim the proposed unified event journal ADR while preserving its decisions and unimplemented status. One file; no scope expansion. 29,504 B → 11,389 B. Two stale path citations → zero. Part of #4205.

Proposed contracts remain in the ADR because no implemented owner can take them without implying acceptance. The coordinator will arrange the required independent sentence review.

Validation

Head cd6cff551adcebf6db258af28c67e89473ec32b9: install, build, format, doc prose and doc links passed. pnpm check:affected --run --head cd6cff551adcebf6db258af28c67e89473ec32b9 passed with zero selected checks, exactCommit=true, checkoutChanged=false (receipt .tmp/validation/run-zm8VEq/receipt.json). CI remains pending. Runtime and device tests do not apply to this docs-only change. No independent reviewer was available in this implementation task.

Migration ledger

Old section	Outcome
Status; rules at a glance	Kept in Status and Proposal; duplicate summary removed.
Context	Kept rationale and channel boundaries; removed dated inventory and file map.
Decision 1: catalog	Kept kind, trait, identity, mapping, ownership and parity rules in Catalog and ownership.
Decision 2: journal	Kept scope, fork, sink, retention, state and exporter constraints in Journal, scopes, and sinks.
Decision 3: progress	Kept transport separation, properties, mirror and rationale in Context, Progress and usage, and Alternatives.
Decision 4: usage	Kept privacy, schema, sequencing and opt-in constraints in Progress and usage.
Invariants	Kept in Proposal and Validation; duplicate summary removed.
Consequences	Kept behavior, cost and compatibility; removed file-count estimate.
Alternatives	Kept all alternatives and reasons.
Validation	Kept implementation gates and regressions.
Migration plan	Kept order, independent steps and paging contract; removed implementation inventory.

No contracts moved to another owner. The session window sidecar and other proposed sink contracts remain here pending implementation.

Wording drift

• Status still says Proposed and that the proposal is unimplemented; descriptions of the existing channels remain context.
• The former normative summary is merged into the proposal and implementation validation. Sink ordering, isolation, scope cloning, redaction, and state ownership retain their scope and exceptions.
• The fork description groups the original three rebind rules; it still covers every mutable binding, nested dispatch, all routed outputs, and post-await isolation.
• Retention consolidates the existing window description with its proposed sink obligation; the sidecar is still non-regenerable, verified before reads, and written before rename.
• The progress alternative states the two original protocol trade-offs and the existing unredacted wire behavior. Mirror emits remain a separate opt-in decision.
• Compatibility retains byte preservation and the single replay redaction exception, including the changelog and fixture update.
• Usage fields, registry vocabularies, exclusions, local-first sequence, and no open strings remain unchanged.
• The migration order is condensed; every step still passes all checks on merge and is independently useful. Gate details remain in Validation.

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