fix: resolve platform sub-package bin/ in runtime seeder (PILOT-209)

[matthew-pilot]

What

pkgBinDir() in src/runtime.ts previously only looked in the main package's bin/<platform>/ directory for native Go binaries. Because bin/ is .gitignore'd and excluded from the files array, published packages never contain it.

The optional platform sub-packages (e.g. pilotprotocol-darwin-arm64@0.1.1) are designed to ship these binaries in their own bin/ directories, but the runtime never checked there — causing the "Binary not found — may be for a different platform" error on all platforms.

Change

Add a sub-package fallback in pkgBinDir(): when the main package bin/<platform>/ is absent, resolve node_modules/pilotprotocol-<platform>/bin/ from the optional dependency installed by npm.

The fallback only resolves when pilotctl (the first binary in BIN_NAMES) actually exists at that path — so a missing or empty sub-package still falls through to the existing error message.

Testing

• npm run build (TypeScript): ✅ clean
• npx vitest run (173 tests): ✅ all pass
• Runtime: 1 file, +10 −1 lines

Related

• PILOT-209: Jira ticket tracking the npm sub-package binary gap
• PILOT-203: Durable fix (per-platform publish CI) — this PR is the runtime-side counterpart that makes published binaries actually discoverable
• PILOT-208: Sibling issue (PyPI wheel wrong-arch binary)

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[matthew-pilot]

🦾 Matthew PR Check — #4 PILOT-209

Status

• State: OPEN · MERGEABLE ✅
• CI: 2/2 green (test ✅, security/snyk ✅)
• Reviews: 0 reviews (awaiting operator)
• Jira: PILOT-209

Summary

sdk-node runtime seeder (pkgBinDir()) only searched the main package bin/<platform>/ for native Go binaries. Because bin/ is .gitignore-d and excluded from npm publish, shipped packages are missing the binaries. Optional platform sub-packages (pilotprotocol-<platform>) are designed to carry them, but the runtime never checked there — causing "Binary not found" on all platforms.

This PR adds a sub-package fallback: when the main-package bin/<platform>/ is absent, resolve node_modules/pilotprotocol-<platform>/bin/ from the optional dependency. Fallback only activates when pilotctl actually exists at that path, so a missing sub-package still falls through to the existing error message.

What's next

• Operator review — please sanity-check the sub-package resolution path
• Merge when ready — CI is green, branch is mergeable, no conflicts

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