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The ControlCenter is the central orchestrator of the Palyra desktop application. It manages the lifecycle of the core daemon (palyrad) and the browser automation service (palyra-browserd), handling their configuration, execution, health monitoring, and log aggregation within a Tauri-based environment.

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ControlCenter Architecture

The ControlCenter struct acts as the supervisor for managed services. It maintains the runtime state, profile configurations, and communication channels for log events.
ComponentRole
ManagedServiceTracks the state of a specific process, including its Child handle, PID, and restart logic.
RuntimeConfigDefines the network ports used by the gateway and browser services.
ServiceKindAn enum identifying the service type: Gateway or Browserd.
LogEventA message sent from process output readers to the supervisor’s internal log aggregator.

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Process Lifecycle State Machine

The supervisor manages services based on a desired_running flag. If a service is marked as desired but is not currently running, the supervisor attempts to spawn it. Sources:

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Supervisor Loop and Backoff

The supervisor runs a continuous loop governed by SUPERVISOR_TICK_MS (500ms). During each tick, it performs the following:
  1. Process Reaping: Checks if Child handles have exited and updates ManagedService state.
  2. Backoff Calculation: If a service needs a restart, it uses an exponential backoff strategy to prevent rapid crash looping.
  3. Process Spawning: Spawns new processes for services that are desired_running and have passed their backoff period.
  4. Log Aggregation: Drains the log_rx channel to update internal VecDeque buffers.

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Exponential Backoff Logic

The backoff is calculated based on the restart_attempt counter. It ensures that subsequent failures result in longer wait times before the next attempt, capped at a maximum duration. Sources:

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Managed Services: palyrad and palyra-browserd

The supervisor handles two primary binaries. It resolves their paths using resolve_binary_path and injects necessary environment variables for communication.

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Environment Variable Injection

When spawning palyrad, the supervisor injects:
  • PALYRA_ADMIN_TOKEN: For Tauri-to-Daemon IPC authentication.
  • PALYRA_BROWSER_AUTH_TOKEN: For Daemon-to-Browserd communication.
  • Port configurations (e.g., PALYRA_GATEWAY_ADMIN_PORT).

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Service Definitions

ServiceBinary NameBinary Override Env
GatewaypalyradPALYRA_DESKTOP_PALYRAD_BIN
Browserdpalyra-browserdPALYRA_DESKTOP_BROWSERD_BIN
Sources:

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Log Rotation and Aggregation

Logs are captured from the stdout and stderr of child processes. To prevent memory exhaustion, the ControlCenter implements a rotation policy.
  1. Capture: tokio::process::Child pipes are wrapped in BufReader.
  2. Channel: Lines are sent via an mpsc channel with LOG_EVENT_CHANNEL_CAPACITY (2,048).
  3. Storage: Each ManagedService maintains a VecDeque<LogLine>.
  4. Rotation: The buffer is capped at MAX_LOG_LINES_PER_SERVICE (400 lines). When the limit is reached, the oldest logs are dropped.
Sources:

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Tauri IPC Commands

The Desktop UI communicates with the ControlCenter via Tauri’s invoke system. These commands allow the user to control the backend processes and view system health.

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Command Reference

IPC CommandFunctionDescription
get_snapshotcommands::get_snapshotReturns a ControlCenterSnapshot containing process status, logs, and diagnostics.
start_palyracommands::start_palyraSets desired_running to true for the gateway.
stop_palyracommands::stop_palyraSets desired_running to false and kills the gateway process.
restart_palyracommands::restart_palyraCycles the gateway process state.
get_settingscommands::get_settingsRetrieves current runtime and profile settings.

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Data Flow: Snapshot Request

Sources: