Files
msd-core/docs/explanation/embeddable-orchestration-system.md
Tom Boucher ffd5370464 fix(#2903): use the command form that actually works in reader-facing docs (#3047)
* fix(#2903): use the command form that actually works in reader-facing docs

Docs told readers to type the colon form, which no runtime registers -- 18 of
19 runtimes use slash-hyphen and the 19th uses shell-var -- so anyone copying an
example got an unrecognized command. Swept 178 occurrences across 53 files,
locale mirrors included so they do not re-diverge from English.

The colon form is a source-authoring token, not a user-facing one: install-time
converters key on it to produce the hyphen form runtimes actually register. So
the sweep is scoped, and three things are deliberately left alone:

- ADRs, which are a historical record; editing their prose falsifies what was
  written at the time.
- The legacy release-notes archive, pending a maintainer decision on whether it
  follows the same historical carve-out. Excluding it keeps a later reversal
  additive rather than a revert.
- Source artifacts under commands, workflows and agents, where the colon form is
  load-bearing. Rewriting those would break the installed-skill guarantee across
  every runtime -- the single largest hazard here.

The plugin namespace form is a real, separate token and survives untouched.

Adds a lint enforcing exactly that boundary, since the correct form genuinely
differs by directory and nothing previously caught the drift.

Also fixes a hardcoded colon form in the capability-matrix generator. The sweep
alone would have left the generated matrix disagreeing with the template that
produces it, so the fix is at the source and the output regenerated.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix(#2903): stop the sweep misquoting source frontmatter

Adversarial review caught three lines where the sweep rewrote a citation of the
literal YAML name: key from a source command file. That key genuinely is the
colon form -- this change's own carve-out logic says source-authoring tokens keep
it -- so the docs ended up misquoting the real files. One of the three is an
acceptance-checklist assertion, which the sweep turned into a false statement.

Restored the three citations to match their sources verbatim, surgically: where a
line carried both a name: citation and a real reader-facing slash command, only
the citation reverted and the command stayed corrected.

The guard needed the same distinction, or it would have flagged the restoration
and reddened the build: a gsd:<cmd> token preceded by name: is a citation of a
source token and is now permitted. The exemption is deliberately narrow -- a bare
gsd:<cmd> anywhere else still fails -- with a test pinning that narrowness.

Also makes the detection case-insensitive. Review found /GSD:next slipped through
silently; no such casing exists in the tree today, so this closes a latent gap
rather than fixing a live one.

Swept the whole tree for further corrupted citations: none beyond the three.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix(#2903): retire the stale-next invariant and sweep next like every other command

Maintainer decision on a genuine conflict between two contracts.

Invariant #3054 banned the literal /gsd-next from user-facing docs because it
named a retired workflow-advance command. But commands/gsd/next.md is a live
command -- the state-aware smart-entry launcher -- and this issue requires docs
to use the hyphen form every runtime actually registers. Both could not hold for
this one command, so docs had been sidestepping the ban by keeping the colon
form, which is exactly the defect this issue exists to remove.

FEATURES.md already recorded the reassignment: the hyphen form "is not the
retired workflow-advance command; it is reserved for the state-aware smart-entry
launcher. Workflow advancement remains under /gsd-progress --next." With that
reassignment the invariant's premise is obsolete and the guard now contradicts
the documented command form, so it is retired with a comment recording why
rather than deleted silently.

next is now swept like every other command, and the earlier exemption added to
the new guard is removed so nothing is special-cased.

Four citations of the literal name: frontmatter key stay in colon form, because
the source file really does carry name: gsd:next and a doc quoting it must
reproduce it verbatim. Two of those lines were reworded to say which side is the
frontmatter key and which is the slash command, since they previously conflated
the two.

Verified the retired scan would now genuinely fail against this tree -- the
conflict was real and resolved, not dodged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* chore(#2903): backfill changeset pr number

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
2026-08-04 13:23:44 -04:00

9.9 KiB
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The Embeddable Orchestration System (EoS)

Explanation — This document describes why GSD is built around one versioned interface for embedding inside many different host applications, and how the interface points, negotiated axes, and adapter shapes fit together. It is not a how-to; for field-level detail see the Host-Integration Interface reference. For the compatibility rules that interface itself follows, see Interface versioning and deprecation policy.


The problem it solves

GSD is a filesystem-native orchestration engine, not a standalone application. Almost all of the useful work it does — running a loop, dispatching an agent, resolving a model, persisting state — happens inside some other program: a CLI, an IDE, or an agentic desktop app. Each of those hosts has its own command surface, its own hook system, its own idea of how a model call gets routed, and its own storage model. There is no shared substrate a priori.

Before 1.7.0, every host integration was wired bespoke: a runtime-specific adapter that reached into GSD's internals however it needed to, and exposed whatever surface that host happened to support. That does not scale. Each new host is a fresh bespoke integration to write and maintain, drift between hosts accumulates silently over time, and no third party can build a host integration without reverse-engineering GSD's internals from source.

The Embeddable Orchestration System (EoS) is the answer: one public, versioned contract — the ADR-1239 Host-Integration Interface — that every host integration is expressed against, first-party and third-party alike (Phase A, #1690). A host does not reach into GSD's internals; it declares which interface points it binds and which values it supports for each negotiated axis, and the engine tells it, deterministically, what it gets.

The contract: interface points, negotiated axes, and a version handshake

The interface has three moving parts.

Six interface points are the places a host can bind to GSD: command (how a user invokes a GSD command), dispatch (how that invocation reaches the orchestration loop), model (how model calls are routed), hooks (how lifecycle events fire), state (how .planning/ state is read and written), and artifact (how generated files are produced). A host does not have to bind all six — degradation per point is graceful and explicit (see degradationFor in the reference).

Eight negotiated axes describe how a given host binds those points, not whether it does. embeddingMode, commandSurface, dispatch, modelMode, hookBus, stateIO, transport, and runtime form a closed vocabulary — a host declares a value from a documented set for each axis (or the undocumented sentinel), and the engine negotiates the resulting capability set. The full value tables live in the reference; what matters conceptually is that these axes describe the shape of a host, not its identity — a terminal CLI and a VS Code extension are simply different points in the same eight-dimensional space, not different kinds of thing the engine has to special-case.

A PROTOCOL_VERSION handshake ties the two together over time. A host declares the interface version it targets; the engine negotiates down to min(host, engine) rather than refusing to talk. A host newer than the running engine gets a warning, not a crash — its declared axes beyond the engine's version are simply not trusted. What counts as an additive change versus a version-bumping breaking one, and how long a deprecated value stays usable, is the subject of its own document: Interface versioning and deprecation policy.

Underpinning all of it is the undocumented sentinel: the permanent, fail-closed fallback for an axis a host says nothing about. GSD never guesses a host's capability from context — a host that omits an axis gets the safe default for that axis, never an assumed one.

Two adapter shapes: imperative and declarative

The single most useful mental model for a given host integration is which of two adapter shapes it uses, set by the embeddingMode axis.

Imperative hosts can run GSD's own shell preamble or programmatic dispatch directly at invocation time (embeddingMode: imperative). The host hands control to GSD's runtime launcher and GSD does the rest, live, on every invocation. Most CLI-style and IDE-embedded hosts work this way — OpenCode, Cursor, Cline, Hermes, Qwen, Kilo, Trae, Kimi, Antigravity, and Augment are all imperative integrations.

Declarative hosts cannot run arbitrary code at dispatch time. They consume static, generated artifacts — frontmatter, config, or another format baked at install time — and interpret them through their own, fixed dispatch mechanism (embeddingMode: declarative). Codex is the current declarative host.

The consequence of that split is concrete, not academic: a declarative host's model configuration is fixed at install time, because there is no live dispatch step at which GSD could re-resolve it. If the model configuration changes after install, a declarative host is silently stale until the next reinstall — which is why GSD warns when a declarative host's model configuration changes without a matching reinstall (#1688). An imperative host has no equivalent gap, because it re-runs GSD's dispatch logic on every invocation.

Three host-capability profiles — programmatic-cli, declarative-cli, and ide — give the axis combinations for the reference cases GSD actually targets: a baseline imperative CLI, a baseline declarative CLI, and a baseline IDE (active model mode, engine-owned hook bus, sandboxed storage). See PROFILE_BASELINES in the reference for the exact axis values each profile fixes.

What 1.7.0 delivered on top of the contract

1.7.0 both published the interface (Phase A, #1690) and put it to work at scale in the same cycle. Fourteen runtimes moved onto the public interface via adapters (#2087–#2100) — existing bespoke integrations were rewritten to express themselves as EoS descriptors rather than as ad hoc code.

Three new hosts joined over the same window, each exercising a different part of the interface: ZCode (#1925), pi (#2102), and a VS Code extension driven entirely through the adapter layer (#2103). Gemini CLI was retired in favor of its successor, Antigravity, which shares its underlying infrastructure (#1928).

A companion gsd-mcp-server (#1681) gives hosts that prefer an MCP transport a way to reach interface points 1 and 5 (command and state) without implementing the shell-preamble dispatch path themselves — a second transport onto the same contract, not a second contract.

The clearest evidence that the contract is doing its job: because every host integration is now expressed as data — a descriptor, not bespoke code — /gsd-surface can reproduce a given runtime's generated agent output byte-for-byte from the same descriptors the installer itself consumes (#1575). Runtime output can no longer drift from what the installer produces, because there is only one source of truth for it.

Where EoS ends and Capabilities begin

EoS is easy to conflate with GSD's other extensibility axis, Capabilities (ADR-857, ADR-1244), because both are commonly described as "third parties extending GSD." They answer different questions, and the distinction matters for anyone building against either surface.

EoS is about where GSD runs — which host application embeds the orchestration engine, and how that host's command surface, model routing, hook bus, and storage bind to the engine. Capabilities are about what GSD does — feature plug-ins that attach at GSD's Loop Extension Points inside the loop that is already running. A host integration and a capability are orthogonal axes: the same capability behaves identically regardless of which host is running the loop, and the same host runs any composed set of capabilities without knowing anything about them.

Each has its own non-endorsing discoverability registry (#2182): the EoS Registry lists third-party host integrations, and the Community Capability Registry lists third-party capabilities. Both share one entry schema shape, one non-endorsement stance, and one submission process — see GSD Registries for the full specification of both.

Why a published interface — and what it costs

Publishing a stable, versioned interface is a deliberate trade. The moment an external host depends on PROTOCOL_VERSION 1's axis vocabulary, that vocabulary becomes a long-term compatibility commitment — Hyrum's Law applies in full: whatever a host observably depends on becomes part of the contract, whether or not it was meant to be. That is the cost, and it is why the versioning policy exists as a separate, disciplined document rather than an informal understanding.

The benefit is the reason 1.7.0's fourteen-runtime migration and three new hosts were tractable at all: a new host is additive descriptor work against a published contract, not a fork of GSD's engine internals. A third-party host author can build and test an integration against the documented axis vocabulary without waiting on, or coordinating with, the core team — the same posture the EoS Registry's non-endorsement stance formalizes for discoverability. The interface is what makes "many hosts, one engine" a scalable design rather than a maintenance burden that grows linearly with every new host.

See also