Struct SubprocessController 

pub struct SubprocessController {
    tab_id: String,
    block_id: String,
    run_lock: Arc<AtomicBool>,
    inner: Arc<Mutex<SubprocessControllerInner>>,
    broker: Option<Arc<Broker>>,
    event_bus: Option<Arc<EventBus>>,
    wstore: Option<Arc<WaveStore>>,
    filestore: Option<Arc<FileStore>>,
    health_monitor: Arc<HealthMonitor>,
    self_ref: Mutex<Option<Weak<Self>>>,
}

SubprocessController manages per-turn subprocess lifecycle for agent blocks.

Unlike ShellController which maintains a long-running PTY process, SubprocessController spawns a fresh process for each user turn. Multi-turn continuity comes from --resume <session-id>.

Fields

tab_id: String

Parent tab UUID.

block_id: String

Block UUID.

run_lock: Arc<AtomicBool>

Prevents concurrent spawns.

inner: Arc<Mutex<SubprocessControllerInner>>

Protected inner state.

broker: Option<Arc<Broker>>

WPS broker for publishing events (blockfile, controllerstatus).

event_bus: Option<Arc<EventBus>>

Event bus for obj:update broadcasts.

wstore: Option<Arc<WaveStore>>

Wave object store for block metadata persistence.

filestore: Option<Arc<FileStore>>

FileStore for write-through persistence of output lines (Phase 1.3).

health_monitor: Arc<HealthMonitor>

Agent health monitor (output activity + error tracking).

self_ref: Mutex<Option<Weak<Self>>>

Weak self-reference for queue drain. Set by set_self_ref after the controller is wrapped in Arc.

Implementations

impl SubprocessController

pub fn new( tab_id: String, block_id: String, broker: Option<Arc<Broker>>, event_bus: Option<Arc<EventBus>>, wstore: Option<Arc<WaveStore>>, filestore: Option<Arc<FileStore>>, ) -> Self

Create a new SubprocessController.

pub fn set_self_ref(self: &Arc<Self>)

Store a weak self-reference so the process_waiter can drain queued messages by calling spawn_turn after the current turn exits. Must be called after wrapping in Arc.

fn try_lock_run(&self) -> bool

Try to acquire the run lock. Returns false if a turn is already in progress.

fn unlock_run(&self)

Release the run lock.

fn set_status(inner: &mut SubprocessControllerInner, status: &str)

Update process status and increment version (must hold inner lock).

fn get_status_snapshot(&self) -> BlockControllerRuntimeStatus

Get the runtime status (snapshot).

fn publish_status(&self)

Publish current controller status via the WPS broker.

fn emit_message_accepted(&self, config: &SubprocessSpawnConfig)

Emit agent-message-accepted for the given config, if it carries a message_id. Called from both spawn_turn (direct path) and the process_waiter drain site (queue path). No-op if the config has no id, or the broker isn’t configured.

pub fn session_id(&self) -> Option<String>

Get the stored session ID (if any).

pub(crate) fn record_captured_session_id_inner( inner: &Mutex<SubprocessControllerInner>, sid: &str, ) -> bool

Record an authoritative session id captured from the CLI’s stdout init/thread.started event. The CLI is the source of truth for which session is live, so this ALWAYS overwrites any prior value of inner.session_id — including values previously hydrated from config on a picker reattach (which may be stale by the time the CLI speaks).

Free-function form (taking &Arc<Mutex<…Inner>> instead of &self) so the spawn_turn stdout-reader tokio task can call it without holding an Arc<Self> reference. The &SubprocessController method below just delegates.

Returns true when the value changed (caller should broadcast the meta update + persist to block meta). Returns false when the new id matches the current one — common when the CLI emits the same session_id on every NDJSON frame within a single turn.

pub(crate) fn hydrate_session_id_from_config(&self, config_sid: Option<&str>)

Hydrate inner.session_id from a config-supplied id when the controller hasn’t seen a value yet.

Picker reattach path: a fresh SubprocessController is registered for the new block, so its inner.session_id is None. The frontend persisted the prior block’s session id into agent:sessionid meta, the websocket / app_api caller read it into SubprocessSpawnConfig::session_id, and this method copies it to inner so the spawn_turn args-builder appends --resume <sid> on the FIRST turn.

Hydration is best-effort, not authoritative. If inner.session_id is already Some we no-op (don’t overwrite a value already in place — could be a captured-from-stdout id from an earlier turn, or a prior hydration on the same reattach). Critically, the CLI’s stdout-emitted session id is authoritative and overwrites any prior value at capture time (see the stdout-reader block in spawn_turn). So if the hydrated value is stale, the FIRST turn passes the stale id via --resume (likely accepted as a no-op or rejected with a “no such session” error from the CLI), the CLI then emits its own session id in the init event, and inner.session_id is overwritten with that authoritative value for subsequent turns. Without the capture overwrite, a stale hydrated id would be re-used forever — that was the bug codex flagged on PR #1018 first cut.

Empty &str is treated as “no value” so the caller can use it unconditionally without filtering.

pub fn spawn_turn(&self, config: SubprocessSpawnConfig) -> Result<(), String>

Spawn a single turn of the agent CLI.

This is the core method — it spawns claude -p, writes the user message to stdin, reads NDJSON from stdout (publishing WPS events), and waits for exit.

If a session_id exists from a previous turn, --resume <sid> is appended to args.

pub fn stop_subprocess(&self, force: bool) -> Result<(), String>

Stop the currently running subprocess.

Trait Implementations

impl Controller for SubprocessController

fn start( &self, _block_meta: HashMap<String, Value>, _rt_opts: Option<Value>, _force: bool, ) -> Result<(), String>

Start the controller. May spawn background tasks. force restarts even if already running.

fn stop(&self, _graceful: bool, new_status: &str) -> Result<(), String>

Stop the controller. graceful waits for process to exit; new_status is the target state.

fn get_runtime_status(&self) -> BlockControllerRuntimeStatus

Get the current runtime status.

fn send_input( &self, input: BlockInputUnion, _seq: Option<u64>, ) -> Result<(), String>

Send input (terminal data, signal, or resize) to the controller. seq is the per-TermViewModel monotonic counter; None means fire-and-forget (no ordering).

fn controller_type(&self) -> &str

Get the controller type (e.g., “shell”, “cmd”).

fn block_id(&self) -> &str

Get the block ID.

fn as_any(&self) -> &dyn Any

Downcast support for concrete controller types.