chore(skills): pin team-mode teammates to Sonnet 4.6

Sprint 37 observed Opus 4.7 teammates in team mode ignoring scope
rules ("don't modify files outside your team"), leaving tasks
half-done, and failing to report back via SendMessage. Closest public
issues are anthropics/claude-code#47598 (4.6 subagent delegation
regression) and claude-agent-sdk-python#577 (SendMessage delivery in
team mode). No 4.7-specific team-mode issue published yet but symptoms
are real.

Fix: every Task spawn with a team_name argument now passes
model: "sonnet". The team lead (the session running the skill) stays
on whatever model the user selected — typically Opus.

Inline Agent spawns without team_name (one-shot reviewers in
/pr-review, research subagents, general-purpose one-offs) are
exempt — they keep their default model. The pin targets long-running
coordination specifically, not every Agent call.

Affected skills:
- sprint-start: step 8d Task template adds model: "sonnet" and
  documents the rule with the 4.7 regression context
- workshop-start: step 5 spawn list adds the model pin with a
  one-line reason

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

@@ -365,11 +365,25 @@ using `TaskUpdate` with `addBlockedBy`.
 For each agent from the `**Agents:**` line, spawn a teammate in the
 background. Spawn all agents in parallel (one message, multiple Task calls):
 
+**Model pin (MANDATORY for team members):** every team-mode spawn —
+i.e. any `Task` with a `team_name` argument — must pass `model: "sonnet"`.
+Sprint 37 observed Opus 4.7 teammates ignoring scope rules, leaving
+tasks half-done, and failing to report back via SendMessage. Sonnet 4.6
+follows literal rules block discipline better. The **team lead**
+(this session, running `/sprint-start`) stays on whatever model the
+user has selected — typically Opus.
+
+**Inline (non-team) Agent spawns are exempt.** One-shot reviewers
+(`/pr-review`), research subagents, and other `Task` calls without a
+`team_name` keep their default model. The pin applies to the
+long-running team-coordination path specifically, not every Agent call.
+
 ```
 Task(
   subagent_type: "{name_lowercase}",
   team_name: "sprint-{N}-{team}",
   name: "{name_lowercase}",
+  model: "sonnet",
   prompt: "You are on the {team} team for Sprint {N}.
     Branch: `sprint-{N}/{team}`
 

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

@@ -61,6 +61,7 @@ Use the Task tool to spawn each agent as a teammate. Each call should:
 - Set `team_name` to the workshop team name
 - Set `name` to the agent name (e.g., "gestalt")
 - Set `subagent_type` to the matching agent type (same as name — see reference table)
+- **Set `model: "sonnet"`** — team-mode participants pin to Sonnet 4.6 for literal-rule-following discipline. Opus 4.7 was observed ignoring scope rules and failing to report back in team mode (Sprint 37). The *team lead* (this session) stays on whatever model the user has selected.
 - Provide a prompt telling the agent to check TaskList for their assigned task
 
 Spawn all agents in parallel (one Task call per agent in a single message). Agents will appear as teammates in the Claude Code UI and pick up their tasks from the shared task list.