[danielgerlag]

Closes #31

This is part 4, the last slice of the contracts split. The remaining plugin commands and events (mcp, mcp-apps, feedback, a2a, embedded content) move to their plugins, and mcp-app-csp.ts moves to plugins/mcp-apps. After this PR the @borg/contracts root defines no plugin command. Its only event is the kernel-guarded borg.channel.inboundMessage.

Commits

1. refactor(a2a): a2aGetStatus moves to @borg/plugin-a2a/contract. a2aConfigSchema, a2aStatusSchema and their types stay in the root because the kernel's A2AService uses them.
2. refactor(feedback): feedbackAskInputSchema, feedbackAsk, feedbackRequested and feedbackResolved move to @borg/plugin-feedback/contract. chat and graphs now depend on that contract.
   • feedbackAnswerSchema and FeedbackAnswer stay in the root: InteractionService parses answers with them, and the SDK exposes the type.
   • Kernel tests:
     • The kernel's human-input rule is keyed on the ids borg.feedback and borg.feedback.ask, not on the feedback schemas. So plugin-manager.test.ts now declares local stand-ins with the same ids instead of making the kernel package depend on a plugin. That file is already on the define* allowlist.
     • The duplicate-choice-id assertion moves unchanged to plugins/feedback/test/contract.test.ts.
3. refactor(mcp): the mcp and mcp-apps contracts move into their plugins.
   • @borg/plugin-mcp/contract gets the borg.mcp.* surface: server status, snapshot, listServers, getStatus, refresh, and appDiscovered with its payload schemas (CSP, permissions, tool, MCP_APP_MAX_MESSAGE_BYTES). It also gets mcpAppSnapshotSchema, which is that payload plus a version, and which mcp's tests parse.
   • @borg/plugin-mcp-apps/contract gets the borg.mcpApps.* surface: invokeTool, cancelTool, toolResponded, and their schemas, plus MCP_APP_RENDERER_ID and MCP_APP_BRIDGE_CHANNEL.
   • mcp-apps depends on mcp's contract, never the reverse.
4. refactor(mcp-apps): packages/contracts/src/mcp-app-csp.ts and its test move unchanged to plugins/mcp-apps. The file is published as @borg/plugin-mcp-apps/mcp-app-csp, and the desktop's embedded-content policy and protocol import it from there. The root no longer re-exports it.
5. refactor(chat): embeddedContentRegistered moves to @borg/plugin-chat/contract.
   • mcp-apps can't own it, because chat consumes it and mcp-apps already depends on chat's contract, so that would be a cycle.
   • embeddedContentSnapshotSchema stays in the root because the SDK's renderer API exposes it.
6. docs: records what stays in the root and why, the one-way contract dependencies, and the full rule set enforced by check-plugin-boundaries. This covers the Split @borg/contracts: plugins own their commands and events #31 criterion "boundary rules are documented".
7. refactor(contracts): export mcpServerIdSchema from the root: a review follow-up. It includes the one sanctioned snapshot edit, described below.

All moves are verbatim. I checked this by diffing the lines removed from packages/contracts/src/index.ts against the new files; only import lines differ. apps/desktop/test/wire-contract.snapshot.txt keeps all 82 commands and 24 events with the same ids, timeouts and digests. Its only change is the one sanctioned line added in commit 7.

mcpServerIdSchema and the sanctioned snapshot edit

The mcp commands and appDiscovered validate server ids with mcpServerIdSchema. It stays defined in the root, next to the persona MCP server config that uses it. Per review, commit 7 exports it, and the mcp contract imports it from @borg/contracts; the earlier mcpServerConfigSchema.options[0].shape.id reach-in is gone.

Sanctioned wire snapshot edit (approved by SE): exporting the schema adds exactly one line to apps/desktop/test/wire-contract.snapshot.txt:

@@ -209,6 +209,7 @@ schema mcpAppToolArgumentsSchema 76d0081d404a68a8
 schema mcpAppToolResponseSchema e64e89b5b0d2b652
 schema mcpAppToolSchema 1cf6bfbdfd4910c9
 schema mcpServerConfigSchema bc16656f6e102b4c
+schema mcpServerIdSchema 044fca3cfee9272f
 schema mcpServerSnapshotSchema b78f38c1e24ca3bf
 schema mcpServerStatusSchema 1e22a54a18e235cd
 schema modelCompletionRequestSchema d6520f9871b40f2a

No other line or digest changed, and the command and event counts are still 82 and 24. This is the only snapshot edit in the whole split.

What stays in the @borg/contracts root, and why

• Bus and definition helpers: defineCommand, defineEvent, the envelope, definition types and command errors.
• Interactions: kind, source, choice, response and pending schemas, plus feedbackAnswerSchema. InteractionService, the desktop IPC and the SDK use them.
• Execution security and provenance: used by the kernel.
• Models and gateway: messages, tools, usage, completions, gateway requests, released completions, and the model descriptor. Used by ModelGateway.
• Usage and cost: CostLedger.
• Loops: LoopManager.
• Personas: includes mcpServerConfigSchema and mcpServerIdSchema, because persona config embeds MCP servers. The mcp contract reuses the id schema.
• Workspaces: WorkspaceService.
• Prompt scanning: the kernel scan stage.
• Tool approval and security metadata: ToolService and the SDK.
• Data classification and channel capacity: the security policy.
• Inbound messages: channelInboundMessage, KERNEL_ONLY_EVENT_IDS and the attachment handle. The kernel publishes and guards this event.
• Connector account ids and persisted key formats: the kernel uses oauthGrantKey.
• embeddedContentSnapshotSchema: the SDK renderer API.
• A2A config and status: A2AService.

Contracts root size (packages/contracts/src/index.ts)

	lines	commands	events	exports
original (before #44)	3210	82	24	410
main (after #53)	1573	7	6	170
this PR	1196	0	1	136

Planted violations

I planted each of these in the new code, ran node scripts/check-plugin-boundaries.mjs, saw the failure, and reverted it:

Plant	Failure
mcp's contract imports mcp-apps's contract (dependency declared)	plugin dependency cycle: @borg/plugin-mcp -> @borg/plugin-mcp-apps -> @borg/plugin-mcp
kernel plugin-manager.ts imports @borg/plugin-feedback/contract	packages/kernel may import no @borg/plugin-* package other than @borg/plugin-sdk
plugin-sdk imports @borg/plugin-chat/contract	packages/plugin-sdk may import no @borg/plugin-* package other than @borg/plugin-sdk
contracts root imports @borg/plugin-mcp/contract	packages/contracts/src may import only zod and relative files inside that directory
import "./main" in plugins/feedback/src/contract.ts	src/contract.ts may import only zod, @borg/contracts, @borg/contracts/<subpath>, or @borg/plugin-<name>/contract
a2a ./contract export removed	@borg/plugin-a2a has src/contract.ts but does not export ./contract
defineEvent(...) in plugins/chat/src/main.ts	... calls defineCommand/defineEvent; only packages/contracts/src and plugins/*/src/contract.ts declare bus contracts
chat imports @borg/plugin-mcp-apps/main	... may import @borg/plugin-mcp-apps only as @borg/plugin-mcp-apps/contract
@borg/plugin-feedback dependency removed from graphs	plugins/graphs/src/executor.ts imports @borg/plugin-feedback/contract but @borg/plugin-graphs does not list @borg/plugin-feedback in dependencies

#31 acceptance criteria

• packages/contracts/src/index.ts contains no plugin-specific command or event definitions. Only the kernel-owned borg.channel.inboundMessage event remains.
• mcp-app-csp.ts lives in plugins/mcp-apps.
• pnpm check:boundaries passes, and the boundary rules are documented in docs/architecture.md.
• pnpm typecheck, pnpm test and pnpm test:e2e pass.

Gates (Node 24, Linux), at 17b6454

• pnpm install --frozen-lockfile: OK.
• pnpm check:boundaries: pass. The lockfile diff is importer entries only: zod for four plugins, @borg/plugin-feedback for chat and graphs, and @borg/plugin-mcp for mcp-apps.
• pnpm typecheck: pass.
• pnpm test: 139 files, 933 tests passed.
• xvfb-run pnpm test:e2e: 44 passed, 2 skipped, 0 failed.

Out of scope: the #45 items and #48.