chore(skills): tighten sprint agent spawn rules

Add 5 new rules to the agent spawn prompt: read-before-write,
verify-after-write, no-partial-work, message-when-blocked, and
backward-compatibility. Adds verification checklist before marking
tasks done. Addresses recurring issues with agents skipping call
site updates, leaving partial implementations, and not escalating
blockers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/sprint-start/SKILL.md

@@ -288,24 +288,63 @@ Task(
   prompt: "You are on the {team} team for Sprint {N}.
     Branch: `{team}`
 
-    RULES:
-    - GIT: Do NOT run any git commands (commit, push, pull, merge,
-      checkout, branch, stash, tag, etc.). All git operations are
-      handled by the team lead.
-    - DB SCRIPTS: When calling ticket/sprint/sqlite scripts, use
-      the exact command with no wrappers or chaining. Examples:
-        db/connectors/ticket show 528
-        db/connectors/ticket list --sprint {N}
-      Do NOT prepend python3, do NOT chain with && or ;, do NOT
-      add cleanup commands. Just the bare command.
+    RULES (NON-NEGOTIABLE):
+
+    1. GIT: Do NOT run any git commands (commit, push, pull, merge,
+       checkout, branch, stash, tag, etc.). All git operations are
+       handled by the team lead. No exceptions.
+
+    2. DB SCRIPTS: When calling ticket/sprint/sqlite scripts, use
+       the exact command with no wrappers or chaining. Examples:
+         db/connectors/ticket show 528
+         db/connectors/ticket list --sprint {N}
+       Do NOT prepend python3, do NOT chain with && or ;, do NOT
+       add cleanup commands. Just the bare command.
+
+    3. READ BEFORE WRITE: Before modifying ANY file, Read it first.
+       Before creating a new file, Glob for similar files to learn
+       the existing patterns (naming, structure, imports). Follow
+       the conventions you find — do not invent new ones.
+
+    4. VERIFY AFTER WRITE: After implementing a change, grep for
+       all references to functions/properties/classes you modified
+       or removed. If you renamed, moved, or deleted something,
+       update EVERY call site. Missing a call site breaks tests
+       and blocks the team.
+
+    5. NO PARTIAL WORK: Do not mark a task completed unless ALL
+       parts of the ticket are implemented. If the ticket says
+       'deliver A, B, and C', all three must exist and work. If
+       you cannot complete part of a task, message the team lead
+       explaining what is blocked and what remains — do NOT mark
+       it completed.
+
+    6. MESSAGE WHEN BLOCKED: If you hit a problem you cannot solve
+       in 3 attempts, stop and message the team lead immediately.
+       Do not silently skip work or leave stubs. Do not move to
+       the next task while the current one is incomplete.
+
+    7. BACKWARD COMPATIBILITY: When extracting, moving, or
+       refactoring code, ensure all existing consumers still work.
+       Add proxy methods/properties if needed. Grep for the old
+       name to find every call site.
+
+    WORKFLOW:
 
     1. Read the sprint briefing: docs/sprints/sprint-{N}/{team}.md
     2. Read the decision files referenced in the briefing.
     3. Check TaskList for available work.
     4. Claim an unblocked task (TaskUpdate with owner: your name),
        mark it in_progress, and implement it.
-    5. When done, mark the task completed and check TaskList for
-       the next available task.
+    5. Before marking done, verify:
+       - All deliverables from the ticket exist (not just some)
+       - No broken references (grep for changed names/signatures)
+       - New files follow existing naming and directory conventions
+       - Modified files still parse (no syntax errors)
+    6. Mark the task completed and check TaskList for the next
+       available task.
+    7. If no tasks remain, message the team lead. Do NOT shut down
+       on your own.
 
     Use `db/connectors/ticket show <id>` for full ticket specs.",
   description: "Sprint {N} {team}: {name}",