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projects/dotfiles/046-pi-subagents-minimal-tracer-bullet-task.md

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+---
+status: resolved
+claimed-by: "019fba91-eabf-76ae-b086-a37ac061d6e8"
+claimed-at: "2026-08-01T13:40:33-04:00"
+completed-at: "2026-08-01T13:55:13-04:00"
+parent: "[[027-pi-subagents-implementation-spec-task]]"
+blocked-by: []
+tags:
+  - ticket/task/afk
+---
+
+# Create the minimal subagent extension tracer bullet
+
+## Question
+
+Build a loadable neutral Pi extension that can start one ad hoc independent subagent non-blockingly, track it through the supervisor, and expose basic list, status, and result surfaces for that child.
+
+## What to build
+
+Create the narrowest end-to-end path for the subagent extension.
+A prompt-only spawn should create an ad hoc worker in independent context, return a child id immediately, track lifecycle state through a supervisor, and let the parent inspect status and retrieve the final result later.
+This slice should establish the extension skeleton, the child runner boundary, the initial status record shape, and the basic tool/command surfaces needed to prove the loop works.
+
+## Acceptance criteria
+
+- [x] `/reload` loads the extension from the managed Pi extensions directory.
+- [x] A spawn call with only `prompt` returns a child id immediately.
+- [x] The child runs in `independent` mode without parent transcript context.
+- [x] Status transitions are visible from accepted through terminal state.
+- [x] Result retrieval returns still-running before completion and the final answer after completion.
+
+## Implementation Notes
+
+Use subprocess RPC for the first runner implementation.
+Keep exact public tool names consistent with the spec, but they may be finalized while coding.
+
+Resolved in branch `pi-subagents-tracer-bullet`, commit `fdf0f89`.
+Implemented a managed `subagents` extension skeleton with `subagent_spawn`, `subagent_list`, `subagent_status`, `subagent_result`, and `subagent_cancel` tool surfaces plus slash-command smoke surfaces.
+The tracer bullet intentionally records `tools: "pi-default"` because actual tool-profile enforcement belongs to [[048-pi-subagents-config-agents-tool-profiles-task]].
+Verified managed extension loading through a temporary `PI_CODING_AGENT_DIR`, live Pi RPC spawn/result behavior, extension derivation build, and `nix flake check`.