feat(desktop): host oab-mcp core as a bundled MCP sidecar (macOS-only) - #9
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The desktop now reaches the control plane over the MCP contract instead of an in-process studio-cp link: it spawns `oab-mcp` as a Tauri sidecar at launch, runs the initialize handshake, and forwards `deploy_list`+`deploy_get` as `tools/call`. Console view-model shape is unchanged. - src-tauri/src/mcp.rs: minimal MCP stdio client (spawn, id-muxed JSON-RPC, handshake, call_tool) - src-tauri/src/lib.rs: register shell plugin, spawn+manage McpClient, bridge deploy_list over MCP; drop studio-cp / aws-config deps - tauri.conf.json externalBin + capabilities sidecar permission - desktop.yml: build oab-mcp for the target triple and bundle macOS (arm64, unsigned); Windows/universal deferred - docs/adr/desktop-core-sidecar.md: decision record (amends ADR-3 slice-2) Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
E0599 in compile-linux — the manage() method needs the Manager trait in scope. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Show core lifecycle + failures on launch, so it's obvious when the app starts and whether the sidecar/handshake went wrong. - src-tauri: forward core lifecycle (spawning → handshake → ready), the sidecar's stderr, exit, and bridge errors to a frontend `app-log` event - console: log.ts pane (streams app-log; browser build notes "no core"), shown above the roster; deduped roster errors also logged Frontend verified locally: tsc --noEmit clean, vitest 8/8, vite build ok. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Display 2 shows every MCP message to/from the sidecar (→ request/notification, ← response), so the raw app↔core interaction is visible and can be captured for debugging. Display 1 stays lifecycle/errors. - src-tauri/mcp.rs: emit every outgoing/incoming JSON-RPC message as `mcp-io` (dir out|in); Activity stays on `app-log` - console: log.ts createPane() + bindBackend() routing app-log/mcp-io into two panes; MCP pane added above the roster Frontend verified locally: tsc clean, vitest 8/8, vite build ok. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Replace the stacked panes with a two-tab switcher; roster stays below. An unread dot flags the hidden tab when it gets new lines, so an error landing on the non-visible tab isn't missed. Frontend-only; verified locally: tsc clean, vitest 8/8, vite build ok. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Three bugs the first live run exposed:
1. Lifecycle logs were lost — the core was spawned in setup(), emitting
"spawning/handshake/ready" before the webview subscribed. Now the frontend
subscribes first, then invokes a `start_core` command; spawn happens with a
listener attached.
2. Tool errors were unreadable — a failed tool call returns isError:true with
the message as text; the client tried to JSON-decode it ("expected ident").
Now isError is surfaced verbatim; decode errors include the raw text.
3. Frontend showed "undefined" — Tauri rejections are strings, not Errors.
Stringify with a helper.
Frontend verified locally: tsc clean, vitest 8/8, vite build ok.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This was referenced Aug 10, 2026
brettchien
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- 'Realizes' ADR-3's deferred streaming, not 'Supersedes' (ADR-3 not yet accepted) - subscriber semantics: read current state then resources/updated deltas (matches MCP; no auto-snapshot on subscribe) - reference the sidecar reader as PR #9 rather than a not-yet-on-main file link Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Static app `version` (0.1.0) can't tell builds apart, so stamp each build with version + short git sha + build time (injected by vite at build; falls back to GITHUB_SHA / "unknown"). Shown under "OAB Studio" in the topbar (hover → build time) and logged to the Activity pane on launch. - vite.config.ts: define __APP_VERSION__/__BUILD_SHA__/__BUILD_TIME__ - adds @types/node (config now uses node builtins) Verified locally: tsc clean, vitest 8/8, vite build stamps "v0.1.0 · <sha>". Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This was referenced Aug 10, 2026
brettchien
marked this pull request as ready for review
August 10, 2026 23:40
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What
Make the MCP server start with the desktop app instead of running separately, and route the desktop's own reads through it — killing the two-divergent-paths problem where agents used
oab-mcpbut the desktop shortcut-linkedstudio-cpin-process.oab-mcpas a Tauri sidecar (externalBin) at launch, does the MCPinitializehandshake, and forwards tool calls.deploy_listbridge =deploy_list(services) +deploy_getper service (per-instance 6-state) over MCP. Console shape unchanged —TauriSource/MockSourcestay interchangeable.src-tauridropsstudio-cp/aws-config— single core path; creds resolve inside the sidecar.Scope (per Brett)
macOS only for now (arm64, unsigned). Windows / universal / signing / auto-update deferred.
Files
src-tauri/src/mcp.rs— minimal MCP stdio client (spawn, id-muxed JSON-RPC, handshake,call_tool)src-tauri/src/lib.rs— shell plugin + spawn/manageMcpClient, bridge over MCPsrc-tauri/tauri.conf.json—externalBin: binaries/oab-mcpsrc-tauri/capabilities/default.json— shell sidecar permission.github/workflows/desktop.yml— buildoab-mcpfor the target triple → bundle macOSdocs/adr/desktop-core-sidecar.md— decision record (amends ADR-3 slice-2)Verification / caveats
Authored on a Linux box with no Tauri toolchain — CI's macOS runner is the compiler here. Draft until
bundle-macosis green. Two spots I couldn't validate locally and may need a CI-driven tweak:capabilities/default.json(shell:allow-spawnscope shape).tauri-buildvalidatesexternalBinpresence atcargo buildtime (compile-linux builds+places the linux sidecar to be safe).MCP handshake assumes protocol
2024-11-05+notifications/initialized; rmcp server should accept.🤖 Generated with Claude Code