A max-tokens step that assembled only tool-call blocks appends an EMPTY-content assistant/message (the usage host). Three consumers each hand-rolled output selection and all let it erase the child's real answer: the in-process readResult and the Activation subagent/end capture took the last message unfiltered, and the SDK backend let any message beat its streamed-text fallback; the in-process driver also had no streamed-text fallback for cancelled turns. dsh-subagent now owns the canonical rule in src/assistant-output.ts (last non-empty assistant message, else the accumulated text-delta stream) and all three consumers apply it. Regression tests in all three packages fail under the previous selections. Closes #1514
subagent/ — subagent capability family
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This family lets an agent delegate work to child agents. Multiple named providers may coexist in one context.
| Package | Role | ctx key |
|---|---|---|
subagent/ |
Defines provider registration, delegation, and continuation | ctx.subagents |
subagent-inprocess/ |
Provides the shared in-process run driver | — |
subagent-spawn/ |
Starts a fresh in-process child | registers on ctx.subagents |
subagent-fork/ |
Starts an in-process child from the parent's completed history | registers on ctx.subagents |
subagent-acp/ |
Starts an out-of-process child over ACP | registers on ctx.subagents |
subagent-codex/ |
Starts a real Codex app-server child | registers on ctx.subagents |
subagent-claude-code/ |
Starts a real Claude Code child through the official Claude Agent SDK | registers on ctx.subagents |
subagent-dsh-sdk/ |
Starts an out-of-process Harness child through the TypeScript SDK | registers on ctx.subagents |
tool-subagent/ |
Exposes delegation to the model | registers on ctx.tools |
tool-subagent-control/ |
Exposes child messaging and listing to the model | registers on ctx.tools |
tool-subagent-report/ |
Provides the child-to-parent report channel | registers in child scopes |
See the decisions for the capability family, continuable children, and control tools.
The subsystem reference — start requests, results, live runs, the provider contract, continuable background children — is docs/subsystems/subagent.md; design rationale in the subagent capability seam, continuable background subagents, and merged subagent control service Agent Notes.