fix(plugin-host): source declared_supports_mcp from the plugin manifest (REQUIREMENT-039)

[Shooksie]

What

The provider plugin host now sources declared_supports_mcp from the plugin's DECLARED manifest field (PluginManifest.supports_mcp) instead of a hardcoded true. First slice of TASK-277 / REQUIREMENT-039.

The #314 (rc.8) plumbing already threads declared_supports_mcp all the way into capabilities().supports_mcp and the MCP-injection decision. This PR only changes its SOURCE from a constant to the manifest.

Changes

• New helper declared_supports_mcp_from_manifest in plugin_backend.rs reads manifest.supports_mcp with a back-compat default of true. discover_provider_plugins calls it instead of the old let declared_supports_mcp = true. Unit test covers None (undeclared -> true), Some(false), Some(true).
• All in-tree PluginManifest struct literals gain supports_mcp: None. This is mechanical fallout of the new protocol field (Rust struct literals must set every field); most sites are test helpers.
• The in-tree animus-plugin-runtime provider manifest emits supports_mcp: None with a TODO(codex-p2) to plumb an explicit opt-out through ProviderInfo. Deferred because it mirrors the same deferral in the protocol repo provider_main, and ProviderInfo has no opt-out field yet.

Back-compat

An undeclared field (older plugins built before protocol 1.2.0, which omit it) resolves to true via unwrap_or(true) — identical to today behavior. Only an explicit false opts a provider out of host MCP-server injection.

Coordination for main session — REQUIRED before merge

• This depends on the animus-protocol change (PR to release/0.7) that adds PluginManifest.supports_mcp. To build now, the animus-protocol git deps in Cargo.toml, crates/orchestrator-cli/Cargo.toml, and crates/orchestrator-daemon-runtime/Cargo.toml are TEMPORARILY repinned from tag v0.7.0-rc.5 to branch agent/v0.7.0/declared-supports-mcp (plus the resulting Cargo.lock update).
• Main session must repin the fleet to the CUT protocol tag (e.g. v0.7.0-rc.9) and cargo update before merge. Draft until then.

Gates

• cargo check --workspace --all-targets: clean.
• cargo animus-fmt: clean. cargo animus-lint (clippy): clean. cargo animus-bin-check: clean.
• Targeted tests: orchestrator-plugin-host supports_mcp tests pass (new + existing); animus-plugin-runtime + orchestrator-core suites pass. One unrelated test (manual_phase_approval_resume_clears_task_pause_marker) fails only under full-suite parallelism and passes in isolation — a pre-existing test-isolation flake, not caused by this change.
• codex review --uncommitted (high effort): no P1. Two P2 findings, both deferred: (1) runtime providers cannot yet declare supports_mcp:false via ProviderInfo — TODO added; (2) a theoretical stale manifest-cache omission — mitigated by the cache mtime-invalidation (a provider emitting the new field is a rebuilt, newer-mtime binary that busts the cache).

Part of TASK-277 / REQUIREMENT-039.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
animus-docs	Ready	Preview, Comment	Jul 9, 2026 10:28pm