[thisguymartin]

Closes #37

What changed

Project .env files, Bun preloads, and inherited startup options could affect the external lane runner before its routing and credential checks. The launcher now clears BUN_OPTIONS and NODE_OPTIONS, disables automatic env-file loading, and uses /dev/null for Bun configuration. Normal exported variables still reach the runner and its provider child.

• Move the TypeScript entrypoint to runner/entry.ts behind the shell launcher.
• Update OMP dispatch and subprocess tests to invoke the launcher directly.
• Add five synthetic regression cases for individual and combined startup inputs, preload suppression, and exported credential/identity preservation.

Ports the launcher isolation from open-pstack PR #113.

Verification

• Bun tests, strict typecheck, static invariants, and plugin validation pass.
• The exact candidate is installed in every affected harness.
• The changed behavior passes from each real user surface.
• The installed version, action, and observed result appear below.

bash scripts/check.sh passed in an isolated checkout containing only this change: 269 tests passed, including the startup cases and existing explicit-deadline/cancellation tests. Bun 1.4.2.

Live evidence:

Harness: Claude Code
Installed: not installed; candidate 8185e8b44fff55eba9429f2d027bb0964059778c
Surface: real parent session
Action: setup, scope, and external dispatch with synthetic startup inputs
Observed: not exercised
Result: not run

Harness: Codex
Installed: not installed; candidate 8185e8b44fff55eba9429f2d027bb0964059778c
Surface: real parent session
Action: setup, scope, and external dispatch with synthetic startup inputs
Observed: not exercised
Result: not run

Harness: OpenCode beta
Installed: not installed; candidate 8185e8b44fff55eba9429f2d027bb0964059778c
Surface: real parent session
Action: setup, scope, and external dispatch with synthetic startup inputs
Observed: not exercised
Result: not run

Harness: OMP
Installed: not installed; candidate 8185e8b44fff55eba9429f2d027bb0964059778c
Surface: pstack-omp parent session using pstack_task
Action: configured dispatch with synthetic startup inputs
Observed: not exercised
Result: not run

A pull request without live evidence remains a draft. Do not merge, tag, release, or roll it out.