Epic: complete first-class Devin CLI support

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Goal

Promote Buzz's existing devin acp preset to first-class managed-runtime support with the same installation, authentication, onboarding, configuration, and lifecycle quality as Claude Code and Codex.

Upstream PR block#3225 already added the tier-2 preset. This epic tracks remaining parity instead of creating another adapter.

Execution order

Order	Issue	Deliverable	Dependency
1	#1	Versioned ACP contract and hermetic fixtures	none
2	#2	Runtime metadata, install/auth/readiness, stable launch	#1
3	#3	Onboarding, model/config normalization, diagnostics	#2
4	#4	Lifecycle gates, opt-in real smoke, docs	#2 and #3
parallel	#5	Generic owner-mediated permissions	independent; not launch-blocking

• test(acp): establish a Devin CLI compatibility contract #1
• feat(desktop): promote Devin to a first-class managed ACP runtime #2
• feat(desktop): add Devin onboarding, models, and config integration #3
• test(docs): verify and document the managed Devin lifecycle #4
• feat(acp): route permission requests to authorized Buzz owners #5 — independent hardening

Repository orientation

Desktop managed runtime
  -> buzz-acp subprocess harness
  -> native ACP-over-stdio agent (`devin acp`)
  -> bundled Buzz CLI / relay credentials
  -> relay replies and observer telemetry

Start with:

• AGENTS.md and CONTRIBUTING.md
• crates/buzz-acp/README.md and crates/buzz-acp/src/{acp,lib,pool}.rs
• desktop/src-tauri/src/managed_agents/discovery.rs
• desktop/src-tauri/src/managed_agents/discovery/presets.rs
• desktop/src-tauri/src/managed_agents/runtime.rs
• desktop/src/features/agents/AGENTS.md
• desktop/src/features/onboarding/ui/
• desktop/src-tauri/src/managed_agents/config_bridge/

Architecture constraints

• Use official native devin acp JSON-RPC stdio.
• Keep capability facts in the Rust runtime catalog and project them to the frontend.
• Discover authentication/model/config through ACP when possible.
• Preserve runtime ID devin, command devin, and args ["acp"]; no record migration should be needed.
• Keep canonical .agents/skills; Devin reads it natively.
• Do not bundle/relicense the proprietary CLI.
• Add no Devin-specific protocol branch without a failing reproduction.
• Keep relay/Nostr changes out of test(acp): establish a Devin CLI compatibility contract #1–test(docs): verify and document the managed Devin lifecycle #4; base support is local runtime/ACP work.

Working agreement

1. Take the first unblocked issue and include assumptions in the PR description.
2. Check current upstream work before editing, especially fix(acp): launch ACP/stdio mode for managed agents with no runtime preset block/buzz#3804.
3. Keep each issue reviewable; do not fold feat(acp): route permission requests to authorized Buzz owners #5 into launch work.
4. Add tests beside behavior and update desktop/src/features/agents/AGENTS.md if config rules change.
5. Activate Hermit before Git/hooks: . ./bin/activate-hermit.
6. Run focused tests during development and just ci before handoff.
7. Commit with git commit -s; add no production unwrap()/expect(), undocumented public APIs, or unsafe code.
8. Use pnpm build:e2e for Desktop mock E2E and follow repository screenshot rules.

Definition of done

• A user can discover/install Devin, authenticate, select it in onboarding, configure a dynamic model, and run a managed turn via devin acp.
• Missing, logged-out, invalid-config, policy/quota failure, and ready states are actionable.
• Existing runtime: "devin" records continue without migration.
• Automated tests need no Devin account; an opt-in real smoke path exists.
• Buzz reads/stores no Devin credentials or account data.
• Existing first-class, preset, and custom runtimes are unchanged.
• just ci passes.

Non-goals

• TUI or devin --print
• Static models/pricing
• Cloud Devin, Outposts, or remote Devin MCP
• New generic session resume work
• Reading/storing/migrating credentials
• Mandatory real Devin CI

References

• Add Devin as a preset ACP harness block/buzz#3225
• feat(acp): bring your own harness (BYOH) — generic ACP runtime seam + settings gallery block/buzz#2773
• feat(desktop): add native Devin ACP runtime block/buzz#3072
• fix(acp): launch ACP/stdio mode for managed agents with no runtime preset block/buzz#3804
• https://docs.devin.ai/cli/reference/commands
• https://cdn.agentclientprotocol.com/registry/v1/latest/registry.json