4094ab610d
* feat(platform): resolver core with locate/inspect/probe tiers and ordered candidates Every resource lookup needs one result shape and one cost contract. `locate` reads metadata only, `inspect` may open files and call OS APIs in-process, `probe` is fresh and the only tier that may spawn or connect. `Resolution.candidates` keeps probe order so fan-out consumers can try every present binary. Linear NS-921. * feat(platform): AppResolver over AppDef with plist, PE, registry, and server.json sources Desktop apps need presence, version, and liveness as separate observations. The runtime file's bearer token is parsed, used for one request, and discarded inside the probe; no public type carries it. Endpoints are accepted only when loopback with a numeric port. * refactor(copilot): gh candidates through locate_command and the Homebrew table First consumer of the resolver. The gh token probe still tries every present binary in order; the allowlist loses its two copilot_auth rows. * feat(platform): availability() over an application declaration locate() + inspect() only, never probes; the fail-closed _version in app.py treats a vendor's plist/PE/registry entry as untrusted input. Salvaged from PR #118122; reads any object with requires_app, min_version, app_for(os) — nothing here imports the MCP catalog. * feat(platform): application declarations parsed into AppDef per OS The parser slice of PR #118122's catalog manifest, re-homed as a catalog-free module: whoever owns an MCP server declares the app it fronts per OS and what it needs, and registers it here. Stdlib + hermes_platform.resolver only. register/lookup/clear are the one seam the MCP check_fn and the skill gate both read. * feat(mcp): check_fn honours a registered application declaration _make_check_fn ANDs the declared app's availability into the connection-alive check; with nothing registered for the server the behaviour is the pre-PR3 connection check. Provenance is explicit registration, not endpoint matching. Returns a plain bool: the registry caches bool(fn()). * feat(skills): requires_apps gate through registered declarations Offer-time filter beside environments:; names resolve through hermes_platform.declaration, an unknown name hides the skill (fail closed). The disk snapshot carries requires_apps and the fast path re-evaluates it (snapshot version bumped to 3): app presence is a host fact that changes without SKILL.md changing. * docs: application declarations page The plugin-facing schema reference: app: and requires: blocks, availability() states, and the two gates that read the registry. Registered under Extending > Plugins in the docs sidebar. * test(platform): declaration parser, availability, gates The PR3 app-block tests re-homed off the catalog: fixtures are dicts passed to parse_declaration, the check_fn gate keys on explicit registration (not endpoint matching), and the import-hygiene probe now covers hermes_platform.declaration and resolver.availability.
100 lines
5.2 KiB
Markdown
100 lines
5.2 KiB
Markdown
# Application declarations
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A plugin whose MCP server fronts a desktop application declares which application that is and what the server needs of it. The core evaluates the declaration on the host and gates the server's tools, and any skill that names the application, on the answer. The parser imports only the standard library and `hermes_platform`.
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The vocabulary lives in `hermes_platform/declaration.py`. A declaration is data plus policy, parsed from plain mappings (already-decoded YAML, JSON, a dict literal — the parser never touches a file):
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```python
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from hermes_platform import declaration
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decl = declaration.parse_declaration(
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"my-server",
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raw_app={"linux": {"presence": "executable", "location": "/opt/my-app/server"}},
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raw_requires={"app": True},
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where="my-plugin/plugin.yaml", # human label used in error messages
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)
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declaration.register("my-server", decl)
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```
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`register(server_name, decl)` stores one declaration under the configured server name in a process-local registry. Loader integration is separate work; core does not read plugin YAML automatically.
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An unregistered MCP server keeps its connection-only check. A skill that explicitly names an unregistered server is hidden. `clear()` removes every registration and is not a per-plugin unload operation. Registrations are process-wide, not profile-scoped.
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## `app` — how to find the application on each OS
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```yaml
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app:
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win32:
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presence: executable
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location: "%ProgramFiles%/Vendor/Vendor App/McpServer/Server.exe"
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version: { kind: uninstall_registry, display_name_prefix: "Vendor App" }
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liveness:
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kind: server_json
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path: "%LOCALAPPDATA%/Vendor/Vendor App/McpServer/server.json"
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pid_key: pid
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url_key: http
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token_key: token
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endpoint_path: /mcp
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darwin:
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presence: bundle
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location: /Applications/Vendor.app
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version: { kind: plist }
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```
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| field | type | rule | maps to `AppDef` |
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|---|---|---|---|
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| `<os>` | `win32` \| `darwin` \| `linux` | at least one; unknown key is an error | `AppDef.os_family` |
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| `presence` | `executable` \| `bundle` | required per OS | `.presence` |
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| `location` | str | required; drive-rooted (`C:\\...`) on Windows, or starting with `~` / `%VAR%` / `$VAR`; UNC paths are rejected so a presence check never touches the network; no `..` segment or URL scheme; expansion at lookup | `.location` |
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| `version.kind` | `pe_resource` \| `plist` \| `uninstall_registry` \| `none` | default `none`; `pe_resource`/`uninstall_registry` only under `win32`, `plist` only under `darwin` | `.version_kind` |
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| `version.display_name_prefix` | str | required when `uninstall_registry` | `.version_arg` |
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| `liveness.kind` | `server_json` \| `none` | default `none` | `.liveness_kind` |
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| `liveness.path` | str | required when `server_json` | `.liveness_path` |
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| `liveness.pid_key` / `url_key` / `token_key` | str | defaults `pid` / `http` / `token` | `.liveness_*_key` |
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| `liveness.endpoint_path` | str | default `/mcp`; the path used for `initialize`, never the one in the file | `.endpoint_path` |
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When `requires.app` is true, an OS missing from `app:` gives `unsupported_os`.
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## `requires` — what the server needs before it is offered
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```yaml
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requires:
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app: true
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min_version: "2.3.0"
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```
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| field | type | rule |
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|---|---|---|
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| `app` | bool | when true, `app:` must exist and the server is gated on presence |
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| `min_version` | str | requires `app: true`; dotted numeric; every applicable `app.<os>` must declare a real `version.kind`; compared numerically per segment, non-numeric characters in a segment are dropped (`2.3.0.12594` ≥ `2.3.0`; prerelease suffixes are not ordered) |
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`requires.app: true` with no `app:` block is a `DeclarationError`.
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## Availability: the one evaluation every reader uses
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`hermes_platform/resolver/availability.py::availability(decl) -> Availability`
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```
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Availability(
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state: available | installed_not_running | missing_app | version_too_old
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| unsupported_os | no_requirements,
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version: str | None, # inspected, when present
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path: str | None, # where the app was found or looked for
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min_version: str | None, # from requires
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)
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```
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- `no_requirements`: no `requires.app`; the application gate passes, but the connection check still applies.
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- `unsupported_os`: `requires.app` and no `app.<this os>` block. Zero I/O.
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- `missing_app`: `locate` found nothing at `location`.
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- `version_too_old`: the version is below the minimum or cannot be read.
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- `available`: present, version acceptable or not required.
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- `installed_not_running`: reserved vocabulary; this evaluator never produces it.
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Evaluation uses `locate` and optional version inspection. It never probes a server, launches an application, or connects. The tool registry retains its existing availability cache.
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## The two gates
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- **MCP `check_fn`** (`tools/mcp_tool_handlers.py::_make_check_fn`): connection alive AND, when a declaration with `requires.app` is registered for the server, `availability(decl).offerable`. Returns a plain `bool` because the registry caches `bool(fn())`.
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- **Skill `requires_apps:` frontmatter** (`agent/skill_utils.py::skill_matches_apps`): each name resolves through `declaration.lookup`; an unknown name hides the skill (fail closed). Offer-time filter, like `environments:`.
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