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Logcat — Event Streaming

logcat is Android's system-wide event log. Every notification, every app error, every broadcast — all streamed from the kernel in real time. strands-adb turns this into agent-consumable events.

One-Shot Dump

result = adb(action="logcat", lines=200)
# → last 200 lines of logcat -d

Filter by tag:

adb(action="logcat", filter="WhatsApp", lines=100)
adb(action="logcat", filter="NotificationManagerService:V *:S")

Continuous Streaming → Event Bus

This is the killer feature. Start a background thread that tails logcat and pushes events to DevDuck's event bus:

adb(action="log_stream_start",
    filter="NotificationManagerService",
    topic="phone.notification")

Now, inside DevDuck, the event bus receives a new event every time a notification is posted. The agent's context is automatically updated.

# Check stream status
adb(action="log_stream_status")
# → running=True, buffered=47 events, started 3m ago

# Stop
adb(action="log_stream_stop")

graph LR
    PHONE["📱 Phone"] -->|adb logcat -v| STREAM["🔁 background thread"]
    STREAM -->|parse| EVENTS["📨 Events"]
    EVENTS -->|publish| BUS["🚌 DevDuck event_bus"]
    BUS -->|inject into context| AGENT["🤖 Agent"]

    style PHONE fill:#3DDC84,color:#000
    style AGENT fill:#fbbf24,color:#000

Parsed Notifications

Raw logcat is noisy. For notifications specifically, use the parsed action:

adb(action="notifications_parsed")
# → [
#   {"app": "WhatsApp", "title": "Mom", "text": "on my way", "time": ...},
#   {"app": "Slack", "title": "#general", "text": "PR ready", "time": ...},
#   ...
# ]

Or raw dump:

adb(action="notifications")

Filters

Standard logcat filter syntax works:

adb(action="log_stream_start",
    filter="ActivityManager:I NotificationManagerService:V *:S")
# → Show INFO+ from ActivityManager, VERBOSE+ from NotificationManager, silence everything else

Agent Recipes

Notification triage

adb(action="log_stream_start",
    filter="NotificationManagerService",
    topic="phone.notifications")

# agent loop sees new notifications in context automatically
agent("""
any new important notifications? reply to mom if she messaged.
""")

App crash monitoring

adb(action="log_stream_start",
    filter="AndroidRuntime:E *:S",
    topic="phone.crashes")

# agent is notified of every app crash

"What's been happening?"

agent("""
what events have happened on my phone in the last 5 minutes?
summarize by app.
""")

Performance

Streaming logcat is cheap — tens of events/sec, fits easily in memory. The background thread parses lines into structured events and buffers the last N (default 500) in memory, publishing each to the event bus.

Privacy

Logcat contains potentially sensitive data: SMS previews, notification content, app state. Treat the event stream like you would any other sensitive telemetry:

  • Don't log it to public places
  • Filter aggressively (filter= narrows scope)
  • Stop the stream when you're done

What's Next