chore(engine): remove legacy Playbook doc type, superseded by Skill

Drop DocType::Playbook variant and all references — playbook extraction
mission was already renamed to skill extraction in the previous session.
Updates CLAUDE.md, architecture docs, context builder, retrieval weights,
mission comments, and store adapter path mapping.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

crates/ironclaw_engine/CLAUDE.md

@@ -13,7 +13,7 @@ See `docs/plans/2026-03-20-engine-v2-architecture.md` for the 8-phase roadmap.
 | **Thread** | Unit of work with lifecycle, parent-child tree, capability leases | Session + Job + Routine + Sub-agent |
 | **Step** | Unit of execution (one LLM call + its action executions) | Agentic loop iteration + tool calls |
 | **Capability** | Unit of effect (actions + knowledge + policies) | Tool + Skill + Hook + Extension |
-| **MemoryDoc** | Unit of durable knowledge (summaries, lessons, playbooks) | Workspace memory blobs |
+| **MemoryDoc** | Unit of durable knowledge (summaries, lessons, skills) | Workspace memory blobs |
 | **Project** | Unit of context (scopes memory, threads, missions) | Flat workspace namespace |
 
 ## Build & Test
@@ -33,7 +33,7 @@ src/
 │   ├── thread.rs         # Thread, ThreadId, ThreadState (state machine), ThreadType, ThreadConfig
 │   ├── step.rs           # Step, StepId, LlmResponse, ActionCall, ActionResult, TokenUsage
 │   ├── capability.rs     # Capability, ActionDef, EffectType, CapabilityLease, PolicyRule
-│   ├── memory.rs         # MemoryDoc, DocId, DocType (Summary/Lesson/Playbook[legacy]/Skill/Issue/Spec/Note)
+│   ├── memory.rs         # MemoryDoc, DocId, DocType (Summary/Lesson/Skill/Issue/Spec/Note)
 │   ├── project.rs        # Project, ProjectId
 │   ├── event.rs          # ThreadEvent, EventKind (18 variants for event sourcing)
 │   ├── message.rs        # ThreadMessage, MessageRole

crates/ironclaw_engine/src/executor/context.rs

@@ -20,7 +20,7 @@ const MAX_CONTEXT_DOCS: usize = 5;
 ///
 /// Retrieves relevant memory docs from the project and injects them as a
 /// system message after the main system prompt. This gives the LLM access
-/// to lessons learned, playbooks, and known issues from prior threads.
+/// to lessons learned, skills, and known issues from prior threads.
 pub async fn build_step_context(
     messages: &[ThreadMessage],
     leases: &[CapabilityLease],
@@ -67,7 +67,6 @@ fn format_docs_as_context(docs: &[MemoryDoc]) -> String {
         let type_label = match doc.doc_type {
             crate::types::memory::DocType::Lesson => "LESSON",
             crate::types::memory::DocType::Spec => "MISSING CAPABILITY",
-            crate::types::memory::DocType::Playbook => "PLAYBOOK",
             crate::types::memory::DocType::Issue => "KNOWN ISSUE",
             crate::types::memory::DocType::Summary => "CONTEXT",
             crate::types::memory::DocType::Note => "NOTE",

crates/ironclaw_engine/src/memory/retrieval.rs

@@ -119,7 +119,6 @@ fn doc_type_weight(doc_type: DocType) -> f64 {
         DocType::Spec => 0.5,     // Missing capability info is highest priority
         DocType::Skill => 0.45,   // Skills with activation metadata and code snippets
         DocType::Lesson => 0.4,   // Lessons prevent repeating mistakes
-        DocType::Playbook => 0.3, // Reusable procedures
         DocType::Issue => 0.2,    // Known problems
         DocType::Summary => 0.1,  // Background context
         DocType::Note => 0.05,    // Scratch notes, lowest priority
@@ -285,8 +284,7 @@ mod tests {
     #[test]
     fn doc_type_weight_ordering() {
         assert!(doc_type_weight(DocType::Spec) > doc_type_weight(DocType::Lesson));
-        assert!(doc_type_weight(DocType::Lesson) > doc_type_weight(DocType::Playbook));
-        assert!(doc_type_weight(DocType::Playbook) > doc_type_weight(DocType::Issue));
+        assert!(doc_type_weight(DocType::Lesson) > doc_type_weight(DocType::Issue));
         assert!(doc_type_weight(DocType::Issue) > doc_type_weight(DocType::Summary));
         assert!(doc_type_weight(DocType::Summary) > doc_type_weight(DocType::Note));
     }

crates/ironclaw_engine/src/runtime/mission.rs

@@ -274,7 +274,7 @@ impl MissionManager {
     /// for `StateChanged { to: Done }`. For each completed non-Mission thread:
     ///
     /// 1. **Error diagnosis** — if trace has issues, fires `thread_completed_with_issues`
-    /// 2. **Playbook extraction** — if thread succeeded with many steps/actions,
+    /// 2. **Skill extraction** — if thread succeeded with many steps/actions,
     ///    fires `thread_completed_with_learnings`
     /// 3. **Conversation insights** — after every N threads in a conversation,
     ///    fires `conversation_insights_due`
@@ -374,7 +374,7 @@ impl MissionManager {
                             }
                         }
 
-                        // ── Trigger 2: Playbook extraction ──────────────
+                        // ── Trigger 2: Skill extraction ──────────────────
                         let action_count = thread
                             .events
                             .iter()
@@ -564,7 +564,7 @@ impl MissionManager {
 
     /// Ensure all three learning missions exist for the given project.
     ///
-    /// Creates (if missing) the self-improvement, playbook extraction, and
+    /// Creates (if missing) the self-improvement, skill extraction, and
     /// conversation insights missions. This is the preferred entry point —
     /// call once at project bootstrap.
     pub async fn ensure_learning_missions(
@@ -1099,7 +1099,7 @@ pub const FIX_PATTERN_DB_TITLE: &str = "fix_pattern_database";
 /// Well-known tag for the fix pattern database.
 pub const FIX_PATTERN_DB_TAG: &str = "fix_patterns";
 
-/// The goal for the skill extraction mission (replaces playbook extraction).
+/// The goal for the skill extraction mission.
 const SKILL_EXTRACTION_GOAL: &str = "\
 You extract reusable skills from successfully completed multi-step threads.
 

crates/ironclaw_engine/src/types/memory.rs

@@ -34,8 +34,6 @@ pub enum DocType {
     Summary,
     /// Durable learning from experience.
     Lesson,
-    /// Reusable multi-step procedure.
-    Playbook,
     /// Detected problem for follow-up.
     Issue,
     /// Missing capability request.

docs/engine-v2-architecture.md

@@ -128,7 +128,6 @@ For trace debugging: `ENGINE_V2_TRACE=1` writes full JSON traces to `engine_trac
 |------|---------|-------------|
 | `Summary` | What a thread accomplished | Conversation insights mission |
 | `Lesson` | Durable learning from experience | Self-improvement mission |
-| `Playbook` | Reusable multi-step procedure | Legacy (superseded by Skill) |
 | `Skill` | Reusable skill with activation metadata and code snippets | Skill extraction mission, v1 migration |
 | `Issue` | Detected problem for follow-up | Self-improvement mission |
 | `Spec` | Missing capability request | Self-improvement mission |
@@ -154,7 +153,7 @@ On each LLM call, two knowledge sources are injected into the system prompt:
 
 ## Skills System
 
-Skills are the v2 replacement for both v1 SKILL.md prompt extensions and v1 playbooks. They provide deterministic, keyword-driven knowledge injection with optional executable code snippets for the CodeAct runtime.
+Skills are the v2 evolution of SKILL.md prompt extensions. They provide deterministic, keyword-driven knowledge injection with optional executable code snippets for the CodeAct runtime.
 
 ### Architecture
 

docs/self-improvement.md

@@ -151,7 +151,7 @@ For Rust bugs in the engine or bridge, the self-improvement thread describes the
 
 ## Fix Pattern Database
 
-A Playbook MemoryDoc maps known trace symptoms to fix strategies:
+A Note MemoryDoc maps known trace symptoms to fix strategies:
 
 | Trace Pattern | Fix Strategy | Location |
 |---|---|---|

src/bridge/store_adapter.rs

@@ -202,7 +202,6 @@ fn doc_workspace_path(doc: &MemoryDoc) -> String {
     let type_dir = match doc.doc_type {
         DocType::Summary => "summaries",
         DocType::Lesson => "lessons",
-        DocType::Playbook => "playbooks",
         DocType::Issue => "issues",
         DocType::Spec => "specs",
         DocType::Note => "notes",