83271191d1
# Conflicts: # docs/config-catalog.md # docs/cordis-catalog/services.md # docs/event-producer-consumer.md # docs/rfc/implemented/architecture/2026-06-18-agent-lifecycle-and-ownership-seams.md # docs/rfc/implemented/architecture/2026-06-20-branded-ids.md # docs/rfc/implemented/simplification/2026-06-20-remove-agent-boundary-mirror-events.md # docs/rfc/proposed/feature/2026-07-07-claude-code-and-codex-subagent-backends.md # docs/rfc/proposed/simplification/2026-06-20-unify-agent-and-session-id.md # packages/bash/tool-bash/README.md # packages/bash/tool-bash/src/index.ts # packages/bash/tool-bash/tests/tools.spec.ts # packages/core/agent-loop/README.md # packages/core/agent-loop/tests/properties.spec.ts # packages/core/agent/README.md # packages/core/agent/src/index.ts # packages/guard/repeat-tool-guard/src/index.ts # packages/hooks/hooks-claude/tests/bridge.spec.ts # packages/subagent/subagent-acp/tests/mock-acp-server.ts # packages/ui/acp/tests/dispose.spec.ts # packages/ui/stdio-agent/src/index.ts # packages/ui/stdio-agent/src/stdio-chat.ts # packages/ui/stdio-agent/tests/stdio-chat.spec.ts # packages/util/brand/src/index.ts
@deepseek-ai/dsh-subagent-fork
The fork provider creates an in-process child seeded with the parent's completed conversation turns. It shares all run mechanics with spawn; the session seed is the only behavioral difference.
Seed boundary
The parent's current tool-calling turn is still open when a subagent starts: its log contains the assistant tool call but not the matching tool result or turn/end. Copying that raw log would give the child an invalid, unbalanced session.
Fork therefore uses completedTurnPrefix(parent.session.events): the contiguous prefix ending at the last turn/end. The child sees all completed parent turns and none of the in-flight turn. If the parent has not completed a turn yet, the seed is empty and the child behaves like a fresh spawn.
The seed transfers conversation history only. The child still receives a fresh flat registration scope; it does not inherit the parent's tool restrictions or authority.
Start and capabilities
start(request) passes the completed-turn seed to startInProcessRun and awaits child publication. The shared driver owns cancellation, depth, customization, result reading, and disposal.
Fork advertises { outputSchema: true, depthLimit: true, toolFilter: true, persona: true }, identical to spawn.
Config
| Key | Meaning |
|---|---|
providerName |
Registry name on ctx.subagents (default fork). |
See dsh-subagent-spawn for the run lifecycle, model inheritance, and depth tracking — all shared. |
Model Experience
Child-agent history and envelope
What the model sees: The child receives the parent's balanced completed-turn surface prefix, then the new task content verbatim. A configured persona shadows prompt text in the child's fresh scope; a tool restriction filters its global wire schemas, executable lookup, and Code Mode SDK bindings but not standalone guidance. The parent's tool view and authority are not inherited. An optional structured-output request adds its child-only contract. The parent's current in-flight turn is excluded.
Token effect: Forking duplicates retained completed history into separate child requests; the child then accumulates its own tokens independently. Persona changes repeated prompt cost, filtering changes schema or generated SDK cost, and a first-turn fork has no inherited history.
Parent tool result, indirectly
What the model sees: The parent receives only the child's own final output through dsh-tool-subagent, not the inherited prefix or intermediate work.
Token effect: Parent input grows by one data-dependent final result retained until compaction.
Known Limitations and Deferred Work
- Runs expose no
sendMessage/resume— the optional runtime capabilities are absent on in-process runs. - The seed is a one-time snapshot — the child sees the parent's completed turns as of the fork and nothing the parent logs afterwards; there is no live context sharing.