debugging-signals-pipeline

name: debugging-signals-pipeline description: > Debug the signals pipeline locally end-to-end. Covers emitting test signals from fixtures, monitoring Temporal workflows via the REST API, reading sandbox agent logs from object storage, inspecting Docker sandbox containers, and diagnosing common failures (stale ClickHouse embeddings, agentsh network denials, inactivity timeouts). Use when a signal isn't reaching the inbox, a signal-report-summary workflow fails, or a sandbox task run times out.

Debugging the signals pipeline

Pipeline flow

emit_signals_from_fixture
  → signal-emitter (Temporal workflow)
    → buffer-signals (batches signals, 5s flush timer)
      → safety_filter_activity
      → flush_signals_to_s3_activity
      → signal_with_start_grouping_v2_activity
        → team-signal-grouping-v2 (30s batch collect window)
          → read_signals_from_s3_activity
          → get_embedding_activity + generate_search_queries_activity
          → run_signal_semantic_search_activity
          → match_signal_to_report_activity
          → assign_and_emit_signal_activity
          → wait_for_signal_in_clickhouse_activity
          → (if new report) signal-report-summary
            → fetch_signals_for_report_activity
            → report_safety_judge_activity
            → select_repository_activity (spawns Docker sandbox)

Emitting test signals

# Emit a single signal from the Zendesk fixture at offset 26
DEBUG=1 python manage.py emit_signals_from_fixture --type zendesk --team-id 1 --offset 26 --limit 1

# Clean up all signal data before re-emitting (avoids stale matches)
DEBUG=1 python manage.py cleanup_signals --team-id 1 --yes

# Check pipeline status
python manage.py signal_pipeline_status --team-id 1 --wait --expected-signals 1 --poll-interval 10

Always clean up before re-emitting to avoid stale embeddings causing phantom report matches.

Monitoring Temporal workflows

The Temporal UI runs at http://localhost:8081. The REST API is useful for scripted inspection.

List recent workflows

curl -s 'http://localhost:8081/api/v1/namespaces/default/workflows?query=ORDER+BY+StartTime+DESC&maximumPageSize=15' \
  | python3 -c "
import sys, json
for wf in json.load(sys.stdin).get('executions', []):
    info = wf['execution']
    status = wf['status'].replace('WORKFLOW_EXECUTION_STATUS_', '')
    print(f'{wf[\"startTime\"][:19]}  {status:20s} {wf[\"type\"][\"name\"]:35s} {info[\"workflowId\"][:90]}')
"

Inspect workflow history

WF_ID="buffer-signals-1"  # or team-signal-grouping-v2-1, signals-report:1:<uuid>
curl -s "http://localhost:8081/api/v1/namespaces/default/workflows/$WF_ID/history?maximumPageSize=200" \
  | python3 -c "
import sys, json
for event in json.load(sys.stdin).get('history', {}).get('events', []):
    etype = event['eventType'].replace('EVENT_TYPE_', '')
    etime = event['eventTime'][:19]
    details = ''
    for key, attrs in event.items():
        if key.endswith('Attributes') and isinstance(attrs, dict):
            if 'activityType' in attrs: details = attrs['activityType'].get('name', '')
            elif 'signalName' in attrs: details = f'signal: {attrs[\"signalName\"]}'
            elif 'startToFireTimeout' in attrs: details = f'timer: {attrs[\"startToFireTimeout\"]}'
            elif 'failure' in attrs: details = f'FAILED: {attrs[\"failure\"].get(\"message\", \"\")[:200]}'
    if details: print(f'  {etime}  {etype:50s} {details}')
"

Inspect a previous run (continued-as-new)

When a workflow has continued-as-new, use the execution.runId query param:

curl -s "http://localhost:8081/api/v1/namespaces/default/workflows/$WF_ID/history?execution.runId=<run-id>&maximumPageSize=200"

Reading sandbox agent logs

Agent logs are stored in object storage (MinIO locally) as JSONL files. The log URL is on the TaskRun model.

# In Django shell (python manage.py shell)
from products.tasks.backend.models import TaskRun
from posthog.storage import object_storage

# Find the most recent task run
run = TaskRun.objects.order_by("-created_at").first()
print(f"status: {run.status}, error: {run.error_message}")
print(f"log_url: {run.log_url}")

# Read the log
content = object_storage.read(run.log_url, missing_ok=True)

# Print last 3000 chars (most useful — shows what happened before failure)
print(content[-3000:])

The log is JSONL with entries like:

{
  "type": "notification",
  "timestamp": "...",
  "notification": { "jsonrpc": "2.0", "method": "_posthog/console", "params": { "level": "debug", "message": "..." } }
}

Key things to look for in the log tail:

• agentsh network events — DENY entries show blocked network calls
• _posthog/progress events — show which setup step the sandbox reached
• _posthog/console debug messages — show sandbox provisioning, cloning, agent startup

Inspecting Docker sandbox containers

# List running sandbox containers
docker ps --filter "name=task-sandbox" --format "table {{.Names}}\t{{.Status}}\t{{.Image}}"

# See processes inside a running sandbox
docker exec <container-name> ps aux

# Read the agent-server log inside the container (while it's still running)
docker exec <container-name> cat /tmp/agent-server.log

The container is named task-sandbox-<task-id>-<random> and uses the posthog-sandbox-base image. Containers are ephemeral — they're removed after the task run completes, so inspect while running.

Common failures

SignalReport matching query does not exist

The assign_and_emit_signal_activity tried to assign a signal to a report that doesn't exist. Usually caused by stale embeddings in ClickHouse after a cleanup_signals that failed to delete them.

Root cause: CLICKHOUSE_DATABASE not set in .env. The cleanup command uses sync_execute which connects to the CLICKHOUSE_DATABASE (defaults to default), but the embedding tables live in the posthog database.

Fix: Add CLICKHOUSE_DATABASE=posthog to .env and restart workers.

Manual cleanup of stale embeddings:

curl -s 'http://localhost:8123/' --data-binary \
  "ALTER TABLE posthog.sharded_posthog_document_embeddings_text_embedding_3_small_1536 DELETE WHERE product = 'signals' AND team_id = 1 SETTINGS mutations_sync = 1"

Verify embeddings are clean:

curl -s 'http://localhost:8123/' --data-binary \
  "SELECT count() FROM posthog.sharded_posthog_document_embeddings_text_embedding_3_small_1536 WHERE team_id = 1 AND product = 'signals'"

Run timed out due to inactivity on select_repository_activity

The sandbox Claude agent went idle for longer than TASKS_INACTIVITY_TIMEOUT_SECONDS. When unset this falls back to a 2 hour timeout — set TASKS_INACTIVITY_TIMEOUT_SECONDS=30 locally to force fast failures.

Diagnosing: Read the agent log from object storage (see above). Check the tail for:

1. agentsh network denials — DENY host.docker.internal means the MCP server URL is blocked by the sandbox network policy. The SIGNALS_REPO_DISCOVERY environment's domain allowlist doesn't include host.docker.internal.
2. No log content at all — sandbox failed to start, check Docker container logs.
3. Claude API errors — check if ANTHROPIC_API_KEY is valid.

buffer-signals sits idle, never receives signals

The signal-emitter completed but buffer-signals never got the submit_signal. This happens when the emitter sent the signal to a previous buffer run that then continued-as-new, and the new run started fresh without the pending signal. Re-emit the signal.

ClickHouse embedding tables "not found" during cleanup

The tables exist in the posthog database but sync_execute queries the default database.

# Verify tables exist
curl -s 'http://localhost:8123/' --data-binary "SHOW TABLES FROM posthog LIKE '%embed%'"

# Check current CLICKHOUSE_DATABASE setting
grep CLICKHOUSE_DATABASE .env

Useful management commands

Key file locations

• Pipeline workflow definitions: products/signals/backend/temporal/
• Buffer workflow: products/signals/backend/temporal/buffer.py
• Grouping workflow: products/signals/backend/temporal/grouping_v2.py
• Report summary workflow: products/signals/backend/temporal/summary.py
• Docker sandbox implementation: products/tasks/backend/logic/services/docker_sandbox.py
• Sandbox Dockerfiles: products/tasks/backend/sandbox/images/
• Agent log polling: products/tasks/backend/logic/services/custom_prompt_internals.py
• Cleanup command: products/signals/backend/management/commands/cleanup_signals.py
• Management command docs: products/signals/backend/management/CLAUDE.md