2026-05-15: Fix backend crash on desktop launch — npx in stripped PATH

Problem

After v1.2.5 fixed lib.rs, the desktop app passed the Prisma migration step but the backend failed to become healthy:

Backend health check 1/30 …
…
Backend did not become healthy after 30 attempts
Some services failed to start

Root cause: backend/src/main.ts also calls execSync('npx prisma migrate deploy') inside NestJS bootstrap. When Tauri spawns the backend with macOS stripped PATH (/usr/bin:/bin:/usr/sbin:/sbin), npx is not found → backend crashes immediately → health checks all fail.

There were two separate places calling npx prisma:

1. src-tauri/src/lib.rs — fixed in v1.2.5
2. backend/src/main.ts — fixed in this release

Fix

Replace execSync('npx prisma migrate deploy') with:

const prismaJs = path.join(__dirname, '..', 'node_modules', 'prisma', 'build', 'index.js');
execFileSync(process.execPath, [prismaJs, 'migrate', 'deploy'], {
  stdio: 'inherit',
  env: { ...process.env },
});

• process.execPath = absolute path to the running node binary (set by Tauri’s find_node() call) — works without PATH
• prismaJs = local prisma binary from backend/node_modules/ — works without PATH
• Also works in Docker and npm run start:dev modes (same node binary, same local prisma)

AGENTS.md checklist

#	Convention	Check
1	Docs	This plan + execution summary
2	Test gates	Backend unit + build + tauri:install launch
3	Self-review	✅
4	Endpoint coverage	N/A
5	Bug-to-Test	tauri:install + double-click verify
6	Seed isolation	N/A
7	Transaction invariants	N/A
8	Plan history	✅ this file
9	Infra test gate	npm run tauri:install + launch verify
10	Env compat	N/A
11	Do-no-harm	Docker/dev mode migration still works
12	Execution summary	Append after done
13	Doc grep	N/A
14	Semver release	v1.2.6 patch

Execution Summary

Commit: 52a118f

Actual changes

• backend/src/main.ts — replaced execSync('npx prisma migrate deploy') with execFileSync(process.execPath, [prismaJs, 'migrate', 'deploy']) using local node_modules/prisma/build/index.js

Deviations from plan

None.

Test results

Gate	Result
Backend build (nest build)	✅ success
Backend unit (npm test)	✅ 319 tests passed
npm run tauri:install	✅ built and installed
Double-click launch	✅ backend healthy on port 3456, dashboard loads
Backend e2e	⏭ not affected
Frontend unit / e2e	⏭ not affected

Key discoveries

• backend/dist/ is gitignored — tauri-build.sh rebuilds it from source during npm run tauri:install. The fix only needs to be in src/main.ts.
• process.execPath in the child NestJS process equals the node binary that Tauri used to spawn it (find_node() result), so the pattern is self-consistent.
• __dirname in compiled CJS dist/main.js = backend/dist/, so path.join(__dirname, '..', 'node_modules', ...) = backend/node_modules/prisma/build/index.js ✅