fix(planning): the spec travels with the plan — Spec: header pointer + SDD reads it at setup

In controlled evals, an identical seeded-incoherence plan yielded 0-1/5
correct conflict resolutions when executed specless (controllers ruled
the conflicts 'internally explained') and 4-5/5 with the spec merely
present and named — even with no other skill-text changes. Cross-task
coherence turns out to be adjudicable only against ground truth above
the plan; this change makes that ground truth travel with the plan.

Claude-Session: https://claude.ai/code/session_0185AJr98gHx5EmwqNeft4Sy

skills/subagent-driven-development/SKILL.md

@@ -140,7 +140,10 @@ a ledger file, not only in todos.
   that happens, recover from `git log`.
 
 Read the plan once, note its context and Global Constraints, and create a
-todo per task.
+todo per task. If the plan names a Spec, read that too: the spec is the
+authority the plan argues from, and conflicts inside the plan resolve
+against it. A plan with no reachable spec gets a ledger note saying so —
+rulings made without one are provisional.
 
 Before dispatching Task 1, scan the plan once for conflicts:
 
@@ -193,14 +196,6 @@ that implementer. Single-file mechanical fixes also take the cheapest tier.
 
 ## The Task Loop
 
-**Batch small same-shape work.** When the plan lists several tasks that are
-each a small, independent edit of the same kind — the same one-line fix,
-constant change, or field addition repeated across files — do not dispatch
-one subagent per task. Compose ONE dispatch brief listing every file and
-its change, send the whole batch to a single subagent, and review its diff
-as one unit. Reserve one-dispatch-per-task for work that needs its own
-judgment, its own tests, or its own review surface.
-
 Everything you paste into a dispatch prompt — and everything a subagent
 prints back — stays resident in your context for the rest of the session
 and is re-read on every later turn. Hand artifacts over as files.

skills/subagent-driven-development/task-reviewer-prompt.md

@@ -86,12 +86,6 @@ Subagent (general-purpose):
     - **Misunderstood:** right feature built the wrong way, wrong problem
       solved
 
-    If the brief lists several files each with its own change (a batched
-    dispatch), check the diff against that list file by file: every listed
-    file must have its corresponding hunk. A listed file the diff never
-    touches is a Missing finding, no matter how clean the rest of the
-    batch looks.
-
     If a requirement cannot be verified from this diff alone (it lives in
     unchanged code or spans tasks), report it as a ⚠️ item instead of
     broadening your search.

skills/writing-plans/SKILL.md

@@ -66,6 +66,9 @@ independently testable deliverable.
 
 **Tech Stack:** [Key technologies/libraries]
 
+**Spec:** [path to the spec/design doc this plan implements — the plan
+argues from the spec, so the spec travels with it; executors read both]
+
 ## Global Constraints
 
 [The spec's project-wide requirements — version floors, dependency limits,