orch: require explicit dispatch execution mode

docs/worktree-execution.md

@@ -2,7 +2,7 @@
 
 ## Purpose
 
-This document defines how code-writing workers should execute in isolated Git worktrees instead of modifying the user's primary working tree.
+This document defines how `orch dispatch --execution-mode code` should run code-writing workers in isolated Git worktrees instead of modifying the user's primary working tree.
 
 The default recommendation is strict mode:
 
@@ -11,7 +11,7 @@ The default recommendation is strict mode:
 - the worker writes code only inside that assigned worktree
 - the leader reviews and integrates the result later
 
-This model is intended for code tasks. Non-code tasks may not need a worktree.
+This model is intended for `execution-mode code`. `execution-mode analysis` stays thread-only and does not allocate a worktree.
 
 ## Why Worktrees
 
@@ -25,11 +25,11 @@ Using a worktree per task attempt gives:
 
 ## Strict Mode
 
-Strict mode means workers only start from an explicit committed Git base.
+Code mode means workers only start from an explicit committed Git base.
 
 Rules:
 
-- `orch dispatch` must resolve a concrete `base_ref` to a commit
+- `orch dispatch --execution-mode code` must resolve a concrete `base_ref` to a commit
 - worker execution must happen in a separate worktree
 - the worker must not modify the user's primary checkout
 - each retry gets a fresh attempt and a fresh worktree
@@ -54,9 +54,9 @@ This keeps worker execution reproducible and avoids hidden divergence from the l
 
 ### 1. Leader Decides a Task Is Ready
 
-`orch` determines that a task may be dispatched.
+`orch` determines that a task may be dispatched, and the leader chooses `--execution-mode code`.
 
-### 2. `orch dispatch` Creates an Attempt Workspace
+### 2. `orch dispatch --execution-mode code` Creates an Attempt Workspace
 
 For one task attempt, `orch` should: