GSD Headless Orchestration

Run GSD commands without TUI via gsd headless. Spawns an RPC child process, auto-responds to UI prompts, streams progress.

Command Syntax

gsd headless [flags] [command] [args...]

Flags:

• --timeout N — overall timeout in ms (default 300000)
• --json — JSONL event stream to stdout
• --model ID — override LLM model
• --verbose — show tool calls in progress output
• --supervised — forward interactive UI requests to orchestrator via stdout/stdin
• --response-timeout N — timeout for orchestrator response in supervised mode (default 30000)
• --max-restarts N — auto-restart on crash with backoff (default 3, 0 to disable)
• --answers <path> — pre-supply answers and secrets from JSON file
• --events <types> — filter JSONL output to specific event types (comma-separated, implies --json)

Exit codes: 0=complete, 1=error/timeout, 2=blocked

Core Workflows

1. Create + Execute a Milestone (end-to-end)

gsd headless new-milestone --context spec.md --auto

Reads spec, bootstraps .gsd/, creates milestone, then chains into auto-mode executing all phases (discuss → research → plan → execute → summarize → complete).

Extra flags for new-milestone: --context <path> (use - for stdin), --context-text <text>, --auto.

2. Run All Queued Work

gsd headless auto

Default command. Loops through all pending units until milestone complete or blocked.

3. Run One Unit

gsd headless next

Execute exactly one unit (task/slice/milestone step), then exit. Ideal for step-by-step orchestration with external decision logic between steps.

4. Instant State Snapshot (no LLM)

gsd headless query

Returns a single JSON object with the full project snapshot — no LLM session, instant (~50ms). This is the recommended way for orchestrators to inspect state.

{
  "state": { "phase": "executing", "activeMilestone": {...}, "activeSlice": {...}, "progress": {...}, "registry": [...] },
  "next":  { "action": "dispatch", "unitType": "execute-task", "unitId": "M001/S01/T01" },
  "cost":  { "workers": [{ "milestoneId": "M001", "cost": 1.50, ... }], "total": 1.50 }
}

# What phase is the project in?
gsd headless query | jq '.state.phase'

# What would auto-mode do next?
gsd headless query | jq '.next'

# Total spend across parallel workers
gsd headless query | jq '.cost.total'

5. Dispatch Specific Phase

gsd headless dispatch research|plan|execute|complete|reassess|uat|replan

Force-route to a specific phase, bypassing normal state-machine routing.

Orchestrator Patterns

Poll-and-React Loop

# Instant state check — no LLM cost
PHASE=$(gsd headless query | jq -r '.state.phase')
NEXT_ACTION=$(gsd headless query | jq -r '.next.action')

case "$PHASE" in
  complete) echo "Done" ;;
  blocked)  echo "Needs intervention" ;;
  *)        [ "$NEXT_ACTION" = "dispatch" ] && gsd headless next ;;
esac

Step-by-Step with Monitoring

while true; do
  gsd headless next
  EXIT=$?
  [ $EXIT -ne 0 ] && break
  # Instant progress check between steps
  gsd headless query | jq '{phase: .state.phase, progress: .state.progress}'
done

Multi-Session Orchestration

GSD tracks concurrent workers via file-based IPC in .gsd/parallel/. See references/multi-session.md for the full architecture.

Quick overview:

Each worker spawns with GSD_MILESTONE_LOCK=M00X + its own git worktree. Workers write heartbeats to .gsd/parallel/<milestoneId>.status.json. The orchestrator enumerates all status files to get a dashboard of all workers, and sends commands via signal files.

# Spawn a worker for milestone M001 in its worktree
GSD_MILESTONE_LOCK=M001 GSD_PARALLEL_WORKER=1 \
  gsd headless --json auto \
  --cwd .gsd/worktrees/M001 2>worker-M001.log &

# Monitor all workers: read .gsd/parallel/*.status.json
for f in .gsd/parallel/*.status.json; do
  jq '{mid: .milestoneId, state: .state, unit: .currentUnit.id, cost: .cost}' "$f"
done

# Send pause signal to M001
echo '{"signal":"pause","sentAt":'$(date +%s000)',"from":"coordinator"}' \
  > .gsd/parallel/M001.signal.json

Status file fields: milestoneId, pid, state (running/paused/stopped/error), currentUnit, completedUnits, cost, lastHeartbeat, startedAt, worktreePath.

Signal commands: pause, resume, stop, rebase.

Liveness detection: PID alive check (kill -0 $pid) + heartbeat freshness (30s timeout). Stale sessions are auto-cleaned.

For multiple projects: each project has its own .gsd/ directory. The orchestrator must track (projectPath, milestoneId) tuples externally.

JSONL Event Stream

Use --json to get real-time events on stdout for downstream processing:

gsd headless --json auto 2>/dev/null | while read -r line; do
  TYPE=$(echo "$line" | jq -r '.type')
  case "$TYPE" in
    tool_execution_start) echo "Tool: $(echo "$line" | jq -r '.toolName')" ;;
    extension_ui_request) echo "GSD: $(echo "$line" | jq -r '.message // .title // empty')" ;;
    agent_end) echo "Session ended" ;;
  esac
done

Event types: agent_start, agent_end, tool_execution_start, tool_execution_end, extension_ui_request, message_update, error.

Filtered Event Stream

Use --events to receive only specific event types — reduces noise for orchestrators:

# Only phase-relevant events
gsd headless --events agent_end,extension_ui_request auto 2>/dev/null

# Only tool execution events
gsd headless --events tool_execution_start,tool_execution_end auto

The filter applies only to stdout output. Internal processing (completion detection, supervised mode, answer injection) is unaffected — all events are still processed internally.

Available event types: agent_start, agent_end, tool_execution_start, tool_execution_end, tool_execution_update, extension_ui_request, message_start, message_end, message_update, turn_start, turn_end.

Answer Injection

Pre-supply answers and secrets for headless runs via --answers:

gsd headless --answers answers.json auto

Answer file schema:

{
  "questions": { "question_id": "selected_option" },
  "secrets": { "API_KEY": "sk-..." },
  "defaults": { "strategy": "first_option" }
}

• questions — question ID → answer (string or string[])
• secrets — env var → value, injected into child process env
• defaults.strategy — "first_option" (default) or "cancel" for unmatched

See references/answer-injection.md for full details.

GSD Project Structure

All state lives in .gsd/ as markdown files (version-controllable):

.gsd/
  milestones/M001/
    M001-CONTEXT.md      # Requirements, scope, decisions
    M001-ROADMAP.md      # Slices with tasks, dependencies, checkboxes
    M001-SUMMARY.md      # Completion summary
    slices/S01/
      S01-PLAN.md        # Task list
      S01-SUMMARY.md     # Slice summary with frontmatter
      tasks/T01-PLAN.md  # Individual task spec

State is derived from files on disk — checkboxes in ROADMAP.md are the source of truth for completion.

All Headless Commands

Quick reference — see references/commands.md for the complete list.