feat(engine): stage skill: property — programmatic plugin skill binding

skills/commission/SKILL.md

@@ -219,6 +219,7 @@ stages:
       {feedback-to: {target_stage} — if this stage has a rejection flow that bounces back to {target_stage}. Infer from the rejection_flow derived in Confirm Design.}
       {gate: true — if this stage is an approval gate}
       {agent: {agent-name} — only if {captain} specifies a non-default agent for this stage. Omit to use the default ensign. The value is the agent file basename without .md.}
+      {skill: {plugin:skill-name} — only if the stage should load a specific skill from an installed plugin. The ensign will invoke Skill("{plugin:skill-name}") before starting stage work. Omit for stages without a plugin-provided skill.}
     - name: {last_stage}
       terminal: true
   transitions:
@@ -263,6 +264,8 @@ Every {entity_label} file has YAML frontmatter. Fields are documented below; see
 
 ### `{stage_name}`
 
+{If this stage has a `skill:` property: "**Load skill:** Invoke `Skill(\"{skill_value}\")` before starting stage work." Otherwise omit this line.}
+
 {A sentence describing who sets this status and what it means for an {entity_label} to be in this stage.}
 
 - **Inputs:** {What the worker reads to do this stage's work — be specific to the mission}

skills/commission/bin/claude-team

@@ -215,12 +215,20 @@ def cmd_build(args):
     if stage_subsection is None:
         return _build_error(f"stage '{stage}' heading not found in {readme_path}")
 
-    # --- Prompt Assembly (9 components) ---
+    # --- Prompt Assembly (10 components) ---
     prompt_parts = []
 
     # 1. Header
     prompt_parts.append(f'You are working on: {entity_title}\n\nStage: {stage}\n')
 
+    # 1.5. Skill loading instruction (conditional)
+    stage_skill = stage_meta.get('skill')
+    if stage_skill:
+        prompt_parts.append(
+            f'**Before starting work**, invoke `Skill("{stage_skill}")` to load '
+            f'the stage skill. Follow its instructions for this stage.\n'
+        )
+
     # 2. Stage definition
     prompt_parts.append(f'### Stage definition:\n\n{stage_subsection}\n')
 

skills/commission/bin/status

@@ -258,7 +258,7 @@ def parse_stages_block(filepath):
             'terminal': state.get('terminal', 'false').lower() == 'true',
             'initial': state.get('initial', 'false').lower() == 'true',
         }
-        for optional_field in ('feedback-to', 'agent', 'fresh', 'model'):
+        for optional_field in ('feedback-to', 'agent', 'fresh', 'model', 'skill'):
             if optional_field in state:
                 stage[optional_field] = state[optional_field]
         result.append(stage)