fix(telemetry): count sub-agent spawns in the engine so exec and serve report them (CW-8190)

subagent_spawn was bumped only in the TUI handler for the spawned event, so
exec and serve always sent 0. The bump now sits at the end of
spawn_subagent_from_input, after the child is registered, which every start
path (agent tool, workflow task, fleet member start) goes through. A refused
spawn is not counted. The TUI count is unchanged because the TUI no longer
bumps on its own.

docs/TELEMETRY.md anchor rewritten; generated agent docs refreshed.
Engine test: spawn_counts_one_subagent_spawn_for_telemetry.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

crates/engine/src/tools/subagent/mod.rs

@@ -16367,6 +16367,7 @@ async fn spawn_subagent_from_input(
         Err(error) => ToolError::execution_failed(format!("Failed to spawn sub-agent: {error}")),
     })?;
 
+    codewhale_telemetry::session_counters().bump(codewhale_telemetry::Counter::SubagentSpawn);
     Ok((result, spawn_metadata))
 }
 

crates/engine/src/tools/subagent/tests.rs

@@ -23585,6 +23585,43 @@ async fn runtime_surface_hardening_resume_from_requires_descendant_control() {
     assert_eq!(manager.read().await.agents.len(), 2);
 }
 
+#[tokio::test]
+async fn spawn_counts_one_subagent_spawn_for_telemetry() {
+    let tmp = tempdir().unwrap();
+    let mut runtime = stub_runtime();
+    runtime.context = ToolContext::new(tmp.path().to_path_buf());
+    let manager = new_shared_subagent_manager(tmp.path().to_path_buf(), 4);
+    let counters = codewhale_telemetry::session_counters();
+    let before = counters.counters().subagent_spawn;
+
+    let (result, _) = spawn_subagent_from_input(
+        json!({"prompt": "inspect the workspace"}),
+        manager.clone(),
+        runtime.clone(),
+        false,
+        None,
+        None,
+        None,
+    )
+    .await
+    .expect("spawn succeeds");
+    assert!(!result.agent_id.is_empty());
+    assert_eq!(counters.counters().subagent_spawn, before + 1);
+
+    let _ = spawn_subagent_from_input(
+        json!({"prompt": "x", "resume_from": "missing-agent"}),
+        manager,
+        runtime,
+        false,
+        None,
+        None,
+        None,
+    )
+    .await
+    .expect_err("a refused spawn is not counted");
+    assert_eq!(counters.counters().subagent_spawn, before + 1);
+}
+
 #[test]
 fn resume_from_rejects_running_source() {
     let tmp = tempdir().expect("tempdir");

crates/tui/src/tui/ui/apply.rs

@@ -35,7 +35,6 @@ pub(crate) fn apply_agent_spawned_status_and_observer(
     prompt_summary: &str,
 ) {
     let label = app.ensure_agent_label(agent_id);
-    codewhale_telemetry::session_counters().bump(codewhale_telemetry::Counter::SubagentSpawn);
     app.push_status_toast_record(
         StatusToast::new(
             format!(

docs/TELEMETRY.md

@@ -331,7 +331,7 @@ The workhorse. Everything a session accumulated ships here, once.
 | `tool_calls` | `execute_tool_with_lock` in `crates/engine/src/core/engine/tool_execution.rs` — surface-agnostic, fires for exec and CLI too |
 | `fleet_dispatch` | `create_queued_run_with_descriptor` in `crates/engine/src/fleet/manager.rs` — the single funnel that `create_run` and `create_queued_run` both land in; counting at either caller would double-count a plain `fleet run`. |
 | `workflow_run` | bumped in `WorkflowTool::execute` (`crates/engine/src/tools/workflow/mod.rs`) only after `parse_workflow_action` returns an `Ok(WorkflowAction)`, never from `input["action"]`. The JSON Schema `enum` in `WorkflowTool::input_schema` is what is published *to the model* — a declaration, not a guard; the real parse also accepts `spawn\|wait\|list\|inspect\|stop\|abort`, and its reject arm (`Invalid workflow action '…'`) embeds the model string verbatim, so a rejected action is never counted. |
-| `subagent_spawn` | `apply_agent_spawned_status_and_observer` in `crates/tui/src/tui/ui/apply.rs` |
+| `subagent_spawn` | `spawn_subagent_from_input` in `crates/engine/src/tools/subagent/mod.rs`, after the sub-agent has been registered; surface-agnostic, so `exec` and `serve` count it too. A refused spawn is not counted. |
 | `mcp_server_connected` | bumped when a server snapshot's `.connected` is true, in `snapshot_from_config` (`crates/engine/src/mcp.rs`); never `name`, `command_or_url`, or `error` — server names are user-chosen and routinely internal infra |
 | `memory_search` | `tool_name == "memory_search"` (the tool registered in `crates/engine/src/tools/native_memory.rs`), counted at the same `execute_tool_with_lock` choke point |
 | `approval_modal_shown` | the `Event::ApprovalRequired` arm of `run_event_loop` (`crates/tui/src/tui/ui/event_loop.rs`; the event is defined in `crates/engine/src/core/events.rs`) |

web/data/agent-docs.generated.json

@@ -259,8 +259,8 @@
       },
       {
         "path": "docs/TELEMETRY.md",
-        "sha256": "0ac65dbd0e1d9d196d1c4421116852c3ab6a855062c375c25b09db993084c563",
-        "content": "# Codewhale product telemetry\n\n> 阅读简体中文版：[zh_hans/TELEMETRY.md](zh_hans/TELEMETRY.md)\n\n**Usage analytics are on by default in the current source.** The first\ninteractive launch gives a localized, nonblocking disclosure naming **Codewhale\nand PostHog**, with a direct route to turn counting off. Notice version `6`\ndescribes this policy; displaying it is not recorded as human acceptance.\nMissing an older acceptance record does not turn a fresh installation off.\nExisting explicit opt-outs remain off across upgrades, and unreadable privacy\nstate fails closed. Environment and CLI kill switches still take precedence.\n\nRead the disclosure with `codewhale config telemetry`. Turn usage off in\n`/settings` or run `codewhale config set telemetry false`. Turning it back on\nin Settings or with `codewhale config set telemetry true` updates the existing\ndurable preference and privacy records for new sessions. The compatibility\ncommand `codewhale config telemetry --accept-notice 5` remains available, but\nis not required for a fresh installation. Collection never includes work content or credentials.\n\nThe PostHog sink is optional and inert until the ingest operator explicitly\nconfigures a project token and approved regional host, and records staging\nproof that the actual egress path does not forward the original client IP.\nSource readiness does not establish a deployment, an activated processor,\nan egress receipt, or a retention setting.\n\nCodewhale does not collect conversations, code, prompts, files, file/repo/branch\nnames, model content, or credentials. It sends no per-turn or per-tool timeline.\nIt does send the closed, aggregate schema below: version and platform classes,\nsession duration/outcome, feature/error counters, and a random install id that\nrotates every 90 days.\n\n**There is now a real endpoint.** An enabled session sends its batches to the\nfirst-party ingest service at `https://telemetry.codewhale.net/v1/telemetry`,\nwhich is the shipped default for `telemetry_endpoint`. What that service is,\nwhat it stores, and what it structurally cannot store is spelled out in \"What\nthe endpoint does\" below.\n\n**To send nothing anywhere, turn telemetry off** (see \"Turning it off\"). To stay\nenabled but contact nobody, set `telemetry_endpoint = \"\"`: batches are then\nappended to `$CODEWHALE_HOME/telemetry/dryrun.jsonl` on your own machine, byte\nfor byte what the server would have received, and no HTTP client is ever\nconstructed. That file is how you audit this document against reality.\n\nThis document is the schema. It is not a summary of the schema: a test in\n`crates/telemetry` parses the field names out of this file and asserts set\nequality against the structs the serializer actually uses, so a field that is\nhere and not in the code — or in the code and not here — fails the build.\n\nLocal saved sessions and `codewhale metrics` remain available with telemetry\ndisabled and require no account or hosted reporting service. Disabling telemetry\ndoes not disable local usage receipts.\n\n## Turning it off\n\nThere are two off switches and they do different things. Both stop collection\ncompletely; only one of them erases anything.\n\n```sh\ncodewhale config set telemetry false     # opt out: stops collection and erases state\nCODEWHALE_TELEMETRY=0 codewhale          # kill switch: stops collection, erases nothing\nDO_NOT_TRACK=1 codewhale                 # the same kill switch, by the common convention\ncodewhale --telemetry false              # the same kill switch, for one command\n```\n\n**`telemetry = false` in the config file is the opt-out.** It is a floor:\n`--telemetry true` and `CODEWHALE_TELEMETRY=1` both lose to it, because a\nsetting you can undo by accident from a wrapper script is not a setting. It\ndeletes the random install id, truncates every buffered event and every dry-run\nrecord, and writes a tombstone. Appends, identity/state writes, and delivery all\nshare the wipe's ordering lock, so once opt-out returns no pre-opt-out write or\nPOST remains in flight. If any part of that wipe fails, the tombstone is still\nthere and the buffer is undrainable — a failed wipe fails closed. Every later\nrun re-asserts the same tombstone for as long as the setting stands, so it\nsurvives. Turning telemetry back on in `/settings` records that explicit preference\nin both existing privacy registers; a fresh launch can then clear the tombstone. Nothing buffered before that point is\never sent.\n\n**The environment variable and the flag are kill switches, not opt-outs.**\nTelemetry is off for the run, nothing is written, nothing is sent — and\nnothing on disk is touched or deleted. That is deliberate: a harness or agent\nthat sets `CODEWHALE_TELEMETRY=0` for one command must not silently discard the\ninstall id and the dry-run records of the person who owns the machine. If you\nwant the erasing kind, use the config file.\n\n`CODEWHALE_TELEMELine truncated
+        "sha256": "fbc3a64c83e0ba69df0b856a80bfd1e4aa67283bf680fa40e7b0b073fed2983f",
+        "content": "# Codewhale product telemetry\n\n> 阅读简体中文版：[zh_hans/TELEMETRY.md](zh_hans/TELEMETRY.md)\n\n**Usage analytics are on by default in the current source.** The first\ninteractive launch gives a localized, nonblocking disclosure naming **Codewhale\nand PostHog**, with a direct route to turn counting off. Notice version `6`\ndescribes this policy; displaying it is not recorded as human acceptance.\nMissing an older acceptance record does not turn a fresh installation off.\nExisting explicit opt-outs remain off across upgrades, and unreadable privacy\nstate fails closed. Environment and CLI kill switches still take precedence.\n\nRead the disclosure with `codewhale config telemetry`. Turn usage off in\n`/settings` or run `codewhale config set telemetry false`. Turning it back on\nin Settings or with `codewhale config set telemetry true` updates the existing\ndurable preference and privacy records for new sessions. The compatibility\ncommand `codewhale config telemetry --accept-notice 5` remains available, but\nis not required for a fresh installation. Collection never includes work content or credentials.\n\nThe PostHog sink is optional and inert until the ingest operator explicitly\nconfigures a project token and approved regional host, and records staging\nproof that the actual egress path does not forward the original client IP.\nSource readiness does not establish a deployment, an activated processor,\nan egress receipt, or a retention setting.\n\nCodewhale does not collect conversations, code, prompts, files, file/repo/branch\nnames, model content, or credentials. It sends no per-turn or per-tool timeline.\nIt does send the closed, aggregate schema below: version and platform classes,\nsession duration/outcome, feature/error counters, and a random install id that\nrotates every 90 days.\n\n**There is now a real endpoint.** An enabled session sends its batches to the\nfirst-party ingest service at `https://telemetry.codewhale.net/v1/telemetry`,\nwhich is the shipped default for `telemetry_endpoint`. What that service is,\nwhat it stores, and what it structurally cannot store is spelled out in \"What\nthe endpoint does\" below.\n\n**To send nothing anywhere, turn telemetry off** (see \"Turning it off\"). To stay\nenabled but contact nobody, set `telemetry_endpoint = \"\"`: batches are then\nappended to `$CODEWHALE_HOME/telemetry/dryrun.jsonl` on your own machine, byte\nfor byte what the server would have received, and no HTTP client is ever\nconstructed. That file is how you audit this document against reality.\n\nThis document is the schema. It is not a summary of the schema: a test in\n`crates/telemetry` parses the field names out of this file and asserts set\nequality against the structs the serializer actually uses, so a field that is\nhere and not in the code — or in the code and not here — fails the build.\n\nLocal saved sessions and `codewhale metrics` remain available with telemetry\ndisabled and require no account or hosted reporting service. Disabling telemetry\ndoes not disable local usage receipts.\n\n## Turning it off\n\nThere are two off switches and they do different things. Both stop collection\ncompletely; only one of them erases anything.\n\n```sh\ncodewhale config set telemetry false     # opt out: stops collection and erases state\nCODEWHALE_TELEMETRY=0 codewhale          # kill switch: stops collection, erases nothing\nDO_NOT_TRACK=1 codewhale                 # the same kill switch, by the common convention\ncodewhale --telemetry false              # the same kill switch, for one command\n```\n\n**`telemetry = false` in the config file is the opt-out.** It is a floor:\n`--telemetry true` and `CODEWHALE_TELEMETRY=1` both lose to it, because a\nsetting you can undo by accident from a wrapper script is not a setting. It\ndeletes the random install id, truncates every buffered event and every dry-run\nrecord, and writes a tombstone. Appends, identity/state writes, and delivery all\nshare the wipe's ordering lock, so once opt-out returns no pre-opt-out write or\nPOST remains in flight. If any part of that wipe fails, the tombstone is still\nthere and the buffer is undrainable — a failed wipe fails closed. Every later\nrun re-asserts the same tombstone for as long as the setting stands, so it\nsurvives. Turning telemetry back on in `/settings` records that explicit preference\nin both existing privacy registers; a fresh launch can then clear the tombstone. Nothing buffered before that point is\never sent.\n\n**The environment variable and the flag are kill switches, not opt-outs.**\nTelemetry is off for the run, nothing is written, nothing is sent — and\nnothing on disk is touched or deleted. That is deliberate: a harness or agent\nthat sets `CODEWHALE_TELEMETRY=0` for one command must not silently discard the\ninstall id and the dry-run records of the person who owns the machine. If you\nwant the erasing kind, use the config file.\n\n`CODEWHALE_TELEMELine truncated
       },
       {
         "path": "docs/public-surface-facts.json",