## Problem Per issue, TMB can spawn many subagents: - N SWE subagents (one per task in `task_create_batch` — no batch-size cap today; observed up to 9 in v0.6.0) - N pr-reviewer subagents (one per task push attempt; retries multiply) - 2–5 consultants per roundtable (parallel) - Phase-2 summary-fill subagents after every `/scan` (one per ~25-file batch) - Sub-subagents (Explore, general-purpose) spawned by bro or SWE mid-conversation Each spawn is its own context that doesn't compress back into bro. SWE has `maxTurns: 150` (built-in cost cap per spawn), but the count of spawns per turn/issue is unbounded. ## Evidence (verified against live source) - `agents/swe.md`: `maxTurns: 150` — single-spawn cap, but no cross-spawn cap. - `agents/pr-reviewer.md`: `tools: ..., Task, ...` — pr-reviewer CAN spawn its own subagents (extending the fan-out tree). - `templates/agents/{architect,ceo,cto,pm}.md`: each has `model: opus` — every consultant spawn pays opus pricing. - No server-side cap on `task_create_batch` batch size (verified in `tools/tasks.ts`). - PreToolUse [Agent] hooks fire on every subagent spawn (3 hooks: `require-task-spec.sh`, `require-feature-branch-active.sh`, `pr-reviewer-no-worktree.sh`) — multiplier cost. ## Plan 1. **`max_parallel_swe` plugin_config key** (default 4); `task_create_batch` larger than the cap chunks into sequential waves of 4. 2. **`urgency: low | normal | high` field** on tasks; `low` tasks run sequentially regardless of cap (cosmetic/lint tasks). 3. **Default urgency**: lint/cosmetic = `low`; normal feature/bug = `normal`; hotfix path = `high`. 4. **pr-reviewer retry cap**: max 2 spawn-attempts before mandatory Human escalation. Track in `pr_review_runs.retry_count`. 5. **Interactive guard at large batches**: ≥6 tasks in one `task_create_batch` triggers an AUQ-style confirmation in interactive mode ("Spawning N subagents. Confirm?"). ## Acceptance criteria - L4 simulation: `task_create_batch` of 12 tasks (default config) runs in 3 sequential waves of 4. - L4 simulation: 3rd pr-reviewer retry refuses and escalates. - L5 dogfood verifies no regression in throughput for normal-size batches. - Schema v3 includes `pr_review_runs.retry_count`. ## Out of scope - Subagent result caching across retries. - Reducing parallel consultants in roundtables (covered in #2910). ## Coordination - Pairs with #2910 (roundtable cap) — both bound parallel fan-out. - Pairs with #2906 (schema v3) — `retry_count` ships in that migration. ## Note on source Verified `swe.md` maxTurns=150 and `pr-reviewer.md` Task tool inclusion. Verified consultant model=opus. Verified PreToolUse [Agent] hook count (3). Previous description's spawn count estimates (8–12 per issue) are accurate.