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msd-core/docs/reference/host-integration-interface.md
Tom Boucher 1008aabd31 fix(#2615): document the effortSurface axis in the host-integration matrix (#2698)
* fix(#2615): document the effortSurface axis in the host-integration matrix

#2481 added `effortSurface` as the ninth negotiated `hostIntegration` axis and
wrote documentation-sourced values into 18 descriptors, but never touched
`docs/reference/host-integration-capability-matrix.md`. The matrix that ADR-1239
designates the cited source of truth had zero occurrences of the axis: no entry in
the axes legend, and no row in any of the per-runtime tables. `src/host-integration.cts`
states "every value is documented or explicitly 'undocumented'" — for this axis
that was false for every runtime.

Adds the legend entry (the `argv` / `none` / `undocumented` vocabulary, plus why
there is deliberately no config-file member) and an `effortSurface` row to all 19
per-runtime tables. Every citation is carried over from #2481's own commit message,
where the values were sourced:

- claude   argv -- `claude --help` documents `--effort <level>`
- opencode argv -- `opencode run --help` documents `--variant`
- codex    argv -- `model_reasoning_effort` is a config.toml key, not a dedicated
                   flag, so the generic `-c key=value` override is the only argv
                   route (still argv)
- 15 hosts undocumented -- their docs state no reasoning setting

kimi-code is the nineteenth section (added by #2603 after #2481) and is the one
runtime with no declared value. Its row and a Documentation-gaps entry record why
rather than inventing one: Kimi Code documents `/effort` (alias `/thinking`), but
only as an INTERACTIVE slash command — `-m, --model` is the only model-adjacent
argv. Neither vocabulary member is accurate (`none` would deny a mechanism the host
has, `argv` would claim one it does not expose), so closing that gap needs a
vocabulary decision, which is a negotiation change and not a documentation one. The
absent value already degrades closed exactly as the sentinel does.

The regression test derives its runtime list from the registry rather than
hardcoding it, so a runtime added later fails until its matrix row exists — the
ratchet whose absence let #2481 add an axis with nothing catching the missing docs.

Closes #2615

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QT3ibz5qJuDuGqpTGRYVGf

* docs(#2615): honest citations for the undocumented rows; fix the four stale 8-axis lists

Two findings from the orthogonal review of the first commit.

1. The 15 `undocumented` rows shared byte-identical text — "searched the runtime's
   official docs (see Sources consulted above)" — which is weaker than this file's
   own convention ("no authoritative doc — searched: <url>") and, worse, implies a
   per-host targeted search that did not happen: each section's Sources-consulted
   list was gathered for OTHER axes and contains no CLI-reference or
   reasoning-effort source. The rows now say plainly what the finding is — an
   ABSENCE established by #2481's cross-host survey — and cite that survey rather
   than implying a URL was checked per host.

2. Four normative docs still described "the eight negotiated axes" and omitted
   effortSurface entirely. The worst of them is
   docs/how-to/add-or-update-a-host-integration.md — the maintainer's own guide for
   onboarding a host, whose Step 2 axis table would have a maintainer reproduce
   exactly the gap #2615 exists to close. Also fixed:
   docs/reference/host-integration-interface.md (which calls itself the normative
   reference and had no effortSurface row at all),
   docs/how-to/author-a-host-plugin.md, docs/registries/README.md ("**exactly** the
   eight … axes keys"), and CONTEXT.md's matching EoS-registry sentence.

Deliberately NOT changed, because they are historical records rather than current
contract: docs/whats-new-1.7.0.md and docs/FEATURES.md's 1.7.0 entry (effortSurface
shipped in 1.8.0 via #2481 — rewriting them would falsify the release history),
ADR-1239's pre-amendment body (already superseded by its own
"Amendment (2026-07-21): effortSurface axis (#2481)"), and ADR-1016's "original
eight axes", which refers to a different axis set entirely.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QT3ibz5qJuDuGqpTGRYVGf

* chore(#2615): backfill changeset PR number (#2698)

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-27 09:02:20 -04:00

4.3 KiB

Reference: the Host-Integration Interface

This is the normative reference for the GSD Host-Integration Interface (ADR-1239) — the versioned, negotiated contract over which any host embeds GSD's orchestration loop. The published surface is the SDK entry (src/host-integration-sdk.cts); this document specifies every symbol on it.

The governing principle: every axis value a host declares must come from that host's authoritative documentation. Where docs are silent, the host declares the undocumented sentinel and the engine degrades fail-closed — it never assumes a capability.


Protocol version

PROTOCOL_VERSION (a positive integer) is the interface version. It governs the negotiated capability set; see the versioning policy for what a bump means.

The nine negotiated axes

HOST_INTEGRATION_AXES is the closed vocabulary. Each axis takes a documented value (or the undocumented sentinel):

Axis Values
embeddingMode imperative | declarative
commandSurface slash-file | slash-programmatic | slash-toml | palette | prose-only
dispatch struct: { namedDispatch, nested, maxDepth, background, subagentToolkit, backgroundDispatch }
modelMode active | passive
hookBus host | engine | none
stateIO filesystem | sandboxed-storage | session-log-append
transport mcp | native-extension
runtime node | bun | sandboxed-web | python | go | rust | electron | other
effortSurface argv | none

Classification + negotiation

  • profileOf(axes) → 'programmatic-cli' | 'declarative-cli' | 'ide' | null.
  • negotiateHostCapabilities(host, engine) → { protocolVersion, effective, points, warnings } — the in-process negotiation. Pure; never throws.
  • handleHandshakeRequest(request) / buildHandshakeRequest(descriptor) — the serialized (out-of-process) form of the same negotiation, JSON-safe across a wire boundary. The two are consistent: a serialized request yields the same effective axes as the in-process call.
  • degradationFor(point, axes) → { level, fallback, unknown? } for one of the six interface points (command | dispatch | model | hooks | state | artifact).
  • hookEventSurfaceFor(hookEvents) → the host-fireable hook events for a dialect ('claude' | 'gemini' | 'opencode-subset'), or null if unknown.
  • shouldFlattenDispatch(dispatch) → true when the orchestrator must run inline (fail-closed).

The engine adapters

All five satisfy a common { kind, runtime, install, uninstall } shape and are constructed fail-closed (they throw if a required host primitive is absent):

Adapter Factory Selected by
Embedding (declarative) createDeclarativeAdapter({runtime}) embeddingMode: 'declarative'
Embedding (imperative) createImperativeAdapter({runtime}) embeddingMode: 'imperative' (also exposes the composed registry)
Model createModelAdapter({modelMode}, {sendRequest?}) modelMode ('active' needs a host sendRequest)
Hook bus createHookBus({bus}, {hostEmit?}) hookBus ('host' needs a host hostEmit)
State IO createStateIO({io}, {backend?}) stateIO ('sandboxed-storage'/'session-log-append' need a host backend)

The declarative + imperative adapters delegate install/uninstall in-process to the same installRuntimeArtifacts engine function bin/install.js uses, so adapter output is byte-identical to a first-party install (gated by tests/golden-install-parity.test.cjs).

Profiles

PROFILE_BASELINES fixes the three reference profiles:

Profile Baseline
programmatic-cli imperative, slash-file, host bus, filesystem, mcp, node
declarative-cli declarative, slash-file, host bus, filesystem, mcp, node
ide imperative, palette, active model, engine bus, sandboxed-storage, sandboxed-web

See also