feat: add run replay for archetype effectiveness analysis

- archeflow-decision.sh records decision points during runs
- archeflow-replay.sh: timeline, whatif, compare commands
- What-if replay with adjustable archetype weights
- /af-replay skill for interactive use
- Tests in archeflow-replay.bats

skills/af-replay/SKILL.md

@@ -0,0 +1,42 @@
+---
+name: af-replay
+description: "Replay and analyze a recorded ArcheFlow run: decision timeline and weighted what-if. Usage: /af-replay <run-id> [--timeline|--whatif|--compare] [--weights arch=w,...]"
+user-invocable: true
+---
+
+# ArcheFlow Run Replay
+
+Inspect a completed or in-progress run logged in `.archeflow/events/<run_id>.jsonl`. Use this to study which archetypes drove outcomes and to simulate **weighted** consensus (what-if).
+
+## Recording (during PDCA)
+
+After each meaningful orchestration choice, log a **decision point** (in addition to `review.verdict` where applicable):
+
+```bash
+./lib/archeflow-decision.sh <run_id> <phase> <archetype> '<input_summary>' '<decision>' <confidence> [parent_seq]
+```
+
+Fields stored: `phase`, `archetype`, `input`, `decision`, `confidence`, `ts` (event timestamp). The event type is `decision.point`.
+
+Lower-level alternative:
+
+```bash
+./lib/archeflow-event.sh "$RUN_ID" decision.point check guardian \
+  '{"archetype":"guardian","input":"diff","decision":"needs_changes","confidence":0.85}' 7
+```
+
+## Commands (from project root)
+
+| Action | Shell |
+|--------|--------|
+| Timeline | `./lib/archeflow-replay.sh timeline <run_id>` |
+| What-if | `./lib/archeflow-replay.sh whatif <run_id> [--weights guardian=2,sage=0.5] [--threshold 0.5] [--json]` |
+| Both | `./lib/archeflow-replay.sh compare <run_id> [--weights ...]` |
+
+- **Timeline** lists `decision.point` rows and `review.verdict` (check phase).
+- **What-if** reads the **last** `review.verdict` per archetype in check. **Original** outcome uses strict any-veto (any non-approve → BLOCK). **Replay** uses weighted mean strictness: each reviewer contributes weight × (1 if not approved, else 0); BLOCK if mean ≥ threshold (default 0.5).
+- **`--json`** emits machine-readable output for dashboards or scripts.
+
+## Learning effectiveness
+
+Correlate `decision.point` confidence and verdicts with cycle outcomes (`cycle.boundary`, `run.complete`) and `./lib/archeflow-score.sh extract` to see which archetypes add signal for which task shapes.

skills/run/SKILL.md

@@ -352,6 +352,7 @@ Emit events via `./lib/archeflow-event.sh <run_id> <type> <phase> <agent> '<json
 | After agent returns | `agent.complete` | archetype, duration_ms, artifacts, summary |
 | Phase boundary | `phase.transition` | from, to, artifacts_so_far |
 | Alternative chosen | `decision` | what, chosen, alternatives, rationale |
+| Orchestrator decision (replay) | `decision.point` | archetype, input, decision, confidence — use `./lib/archeflow-decision.sh` |
 | Reviewer verdict | `review.verdict` | archetype, verdict, findings[] |
 | Fix addressing review | `fix.applied` | source, finding, file, line |
 | End of PDCA cycle | `cycle.boundary` | cycle, max_cycles, exit_condition, convergence |
@@ -403,6 +404,12 @@ Scores stored in `.archeflow/memory/effectiveness.jsonl`. After 10+ runs, recomm
 
 ---
 
+## Run replay (decision log + what-if)
+
+After key choices (routing, fast-path skip, escalation), emit `decision.point` via `./lib/archeflow-decision.sh` so runs can be inspected with `./lib/archeflow-replay.sh timeline|whatif|compare <run_id>`. Weighted what-if helps estimate how much each review archetype swayed the effective ship/block outcome. See skill `af-replay`.
+
+---
+
 ## Dry-Run Mode
 
 When `--dry-run`: Run Plan phase only. Display workflow, agent counts, confidence scores, cost estimate. Ask user to proceed. If yes, continue with `--start-from do`.

skills/using-archeflow/SKILL.md

@@ -7,7 +7,7 @@ description: Use at session start when implementing features, reviewing code, de
 
 On activation, print ONE line then proceed silently:
 ```
-archeflow v0.8.0 · 23 skills · <domain> domain
+archeflow v0.9.0 · 24 skills · <domain> domain
 ```
 Domain auto-detected: `writing` if `colette.yaml` exists, `research` if paper/thesis files, `code` otherwise.
 
@@ -46,6 +46,7 @@ Do NOT use for: single-line fixes, questions, reading/exploring, config tweaks,
 | `/af-memory` | Cross-run lesson memory |
 | `/af-fanout` | Colette book fanout via agents |
 | `/af-dag` | DAG of current/last run |
+| `/af-replay <run_id>` | Decision timeline + weighted what-if on recorded events |
 
 ## Mini-Reflect Fallback