fix(release): build @book.dev/mcp before the desktop sidecar so bun can resolve it

[eliotlim]

Problem

The v2.1.0 desktop Release fails on all three platforms (macOS/Windows/Linux) at "Build Tauri bundles":

error: Could not resolve: "@book.dev/mcp". Maybe you need to "bun install"?
    at packages/server/src/mcpHttp.ts:41

during bun build packages/server/src/bin.bun.ts --compile (the sidecar compile).

Root cause

AGENT-5 (#150) made packages/server depend on @book.dev/mcp (app.ts → mcpHttp.ts imports createOpenBookMcpServer). Bun --compile resolves that workspace package via its main: dist/index.js. Root package.json build:libs was updated to build mcp in order (sdk → ui → mcp → server), but the Tauri beforeBuildCommand in tauri.conf.json still hand-listed only sdk → ui → server:sidecar, so mcp was never built before the compile.

@book.dev/server is only a devDependency of @book.dev/mcp and nothing in packages/mcp/src imports it, so mcp builds cleanly before the sidecar (the cycle is test-only).

Fix

1. tauri.conf.json beforeBuildCommand: build @book.dev/mcp before build:sidecar (parity with build:libs).
2. packages/server/scripts/build-sidecar.mjs: on-demand build @book.dev/mcp if its dist/index.js is missing (mirrors the existing viewer-bundle on-demand build) so a standalone build:sidecar is self-sufficient.

Verification (reproduced the real bun --compile — mocked tests hid the original break)

• Reproduced the exact Could not resolve "@book.dev/mcp" failure with packages/mcp/dist absent.
• After the fix (mcp/dist absent, exercising change Load workspace from filesystem #2): pnpm --filter @book.dev/server run build:sidecar succeeds — logs @book.dev/mcp dist missing — building it…, builds mcp, compiles the sidecar → openbook-server-aarch64-apple-darwin, 83.8 MB, Mach-O 64-bit executable arm64.
• rm -rf packages/mcp/dist then re-run: on-demand rebuild works, binary re-produced.
• Binary --help runs (exit 0).

Board: AGENT-8 (under the Agent epic).

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
app.book.pub	Ready	Preview, Comment	Jul 13, 2026 3:15pm