[FEATURE] Support ACP provider bridge for Claude/GPT subscription clients

[Joncallim]

ADR

0001-acp-provider-bridge.md

Goal

Implement the smallest viable ACP integration by building a concrete Claude Code ACP adapter over local stdio.

Scope

• Define ACP provider interface
• Implement Claude Code ACP adapter
• Support local stdio transport
• Stream responses
• Handle cancellation and failures
• Expose provider through existing provider abstraction

Out of Scope

• Generic ACP client framework
• Remote ACP transports
• Multi-provider ACP support
• Workforce integration

Acceptance Criteria

• FORGE can invoke Claude Code through ACP
• Responses stream correctly into task execution
• Failures are surfaced consistently
• Provider implementation can be swapped behind the interface

Notes

This issue reflects the ADR first-slice recommendation and intentionally avoids building a generalized ACP ecosystem.

[Joncallim]

Use the Zed ACP to make this work:
https://agentclientprotocol.com/get-started/agents

Make the entire list of agents available; but web login should be used where possible. This is primarily a GUI-driven dev environment, not a CLI-driven one.

[Joncallim]

This is clear in intent and goal, but it's a cross-cutting architectural change (new provider abstraction, health-state model, UI routing, security boundary around subscription sessions) rather than a single agent-sized task. Per this repo's working agreement, changes like this should go through an Architect-led design pass (ADR covering the ACP client/adapter approach, provider capability discovery model, and the credential-handling boundary) before implementation starts, rather than being implemented ad hoc.

Not implementing this in the current pass — flagging so it doesn't silently stall. Happy to kick off the Architect design pass as a dedicated task if you want to prioritize it next.

[Joncallim]

Architect design pass done: docs/adr/0001-acp-provider-bridge.md in PR #36. Proposes one concrete adapter (local Claude Code ACP/stdio bridge) as the first slice instead of a generic ACP client, since there's no second real client yet to validate a generic abstraction against. Open decisions for you are listed in the ADR and PR description.