## Summary
This makes the advertised mid-run steering path real: users can send
append or interrupt steering messages through the API, CLI, and web UI,
and the worker delivers them to live API-mode agent sessions or buffers
them for the next session. The change adds the control protocol, session
interrupt machinery, workflow hub, server route/OpenAPI/client updates,
and UI feedback needed for the whole path.
### Plan Summary
- Add `SteerKind`/`run.steer` wire protocol and `POST /runs/{id}/steer`
- Deliver steers through subprocess JSONL or the in-process
`SteeringHub`
- Support append and interrupt behavior in agent sessions, with bounded
buffering and events
- Expose steering in the CLI/web UI and surface SSE toasts
## Flow
```mermaid
flowchart TB
UI["CLI / Web UI"] --> API["POST /runs/{id}/steer"]
API -->|"subprocess transport"| Control["Worker control JSONL"]
API -->|"in-process transport"| Hub["SteeringHub"]
Control --> Hub
Hub -->|"active API sessions"| Session["SessionControlHandle"]
Hub -->|"no active session"| Pending["Pending buffer"]
Pending -->|"first future API session"| Session
Session --> Agent["Session round loop"]
Agent --> Events["RunEvent stream"]
Events --> UI
```
## What changed and why
- Agent sessions now expose a lightweight `SessionControlHandle`, drain
steering at the top of each round, and use a replaceable round
cancellation token for interrupts. LLM waits are cancelled promptly,
while tool execution observes cancellation cooperatively so every
committed `tool_use` still gets a matching `tool_result`.
- `SteeringHub` owns active API session registration, broadcast
delivery, pending buffering, FIFO queue caps, and steering
lifecycle/drop events. A completion coordinator closes the
final-response race without introducing a workflow dependency into the
agent crate.
- The server route replaces the 501 stub, validates run state and
best-effort CLI-only steerability, and forwards through either
subprocess control JSONL or the in-process hub. OpenAPI and generated
clients now include the request type.
- The CLI and web UI can send append or interrupt steers. Run detail and
board views open the new composer, and shared SSE subscriptions now
support per-subscriber event callbacks so invalidation and steering
toasts can coexist on one EventSource.
## Review notes
- Steering actors stay on top-level `RunEvent.actor`; event props only
carry steering kind/drop metadata.
- Buffered steers replay as append messages to the first API session
that registers after an empty-active period. Per-stage targeting remains
out of scope.
- CLI-mode agent stages are still not steerable; the server returns a
best-effort 409 when all active agent stages are CLI-mode, while the
worker hub remains the authoritative safety net.
- No persistence or schema migration is required; active and pending
steering state is in memory.
- New tests focus on protocol round-trips, hub buffering/bounds, session
steering-loop behavior, SSE fanout, and basic server rejection paths.
⚒️ Generated with [Fabro](https://fabro.sh)
---------
Co-authored-by: Fabro <noreply@fabro.sh>
Co-authored-by: Bryan Helmkamp <bryan@brynary.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Invert the docs convention so the Mintlify-published site lives under
docs/public/ and internal artifacts (strategy docs, brainstorms, plans,
etc.) sit at docs/ root or docs/internal/. Tools that default to writing
into docs/ now land in the catch-all instead of leaking into the
published tree.
- Move Mintlify content (administration/, agents/, api-reference/,
changelog/, core-concepts/, examples/, execution/, getting-started/,
human-tools/, integrations/, languages/, reference/, tutorials/,
workflows/, images/, logo/, docs.json, favicon.svg, dot-highlight.js)
into docs/public/.
- Collapse docs-internal/ into docs/internal/.
- Update Rust path references (fabro-api/build.rs, fabro-server,
fabro-dev), TypeScript generator arg, CI path filters, clippy.toml
reasons, AGENTS.md/CLAUDE.md, and README.md image refs.
Mintlify dashboard project root must be updated to docs/public/ in a
follow-up. .mintignore move/trim and .claude/skills/ updates land in a
separate commit.
2026-04-27 07:21:13 -07:00
Renamed from docs/human-tools/steering.mdx (Browse further)
