[codex] Define MCP-first ACP workspace contract

[nick-pape]

Summary

Defines Fledgling's minimum ACP workspace contract as MCP-first: ACP remains the orchestration protocol, while file and command capabilities come from MCP tools rather than ACP host filesystem or terminal APIs.

Changes

• Adds README language documenting the ACP/MCP capability split.
• Clarifies inert ACP host filesystem/permission stubs in the smoke client, host-log CLI, and web demo client.
• Adds guardrail coverage for the advertised minimum initialize() capabilities.
• Adds a prompt-flow test that fails if ACP host permission or filesystem methods are called.

Validation

• pnpm test in packages/acp-agent
  • 4 test files passed
  • 19 tests passed

Notes

ACP filesystem/terminal compatibility remains future work for #11 and #12. Permission bridging for MCP-backed writes and commands remains separate work for #13.

[Copilot]

Pull request overview

Defines and documents an MCP-first workspace capability contract for Fledgling: ACP is used for orchestration (sessions/turns/cancel/load), while workspace file/command functionality is expected to come from MCP tools (not ACP host filesystem/terminal APIs).

Changes:

• Documented the ACP vs MCP responsibility split and clarified the current “MCP-first” workspace contract in the root README.
• Made ACP host filesystem/permission surfaces explicitly inert (documented as stubs) in the smoke client, host-log CLI, and web demo client.
• Added guardrail tests to lock in the minimum initialize() capabilities and to fail if prompt flow calls ACP host permission/filesystem methods.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
README.md	Adds explicit ACP/MCP capability contract documentation and updates “Current Limitations” accordingly.
packages/web-demo/src/acp-demo.ts	Clarifies the demo ACP client’s filesystem/permission methods are inert stubs (MCP workspace tools are the real backend).
packages/acp-host-log/src/index.ts	Clarifies logging host filesystem/permission methods are inert stubs and should not be invoked in MCP-first mode.
packages/acp-agent/tools/smoke-client.mjs	Clarifies smoke client filesystem/permission methods are inert stubs and should not be invoked in MCP-first mode.
packages/acp-agent/src/agent-prompt-cancellation.test.ts	Adds capability-contract and “do not call ACP host fs/permission methods” guardrail coverage.

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