fix(coding-agent): isolate Inspector import crashes

[minpeter]

Summary

• hand an inherited fixed Node Inspector endpoint from the launcher to cli-main
• keep Inspector VM dynamic-import recovery fail-closed by default
• allow an explicit startup opt-in for the exact reported evaluator rejection
• preserve the existing fatal path for application VM, late environment mutation, direct uncaught exceptions, and
  unrelated failures

This is an independent one-commit PR based directly on current main; it does not depend on compaction PR #310 or
the fork's compaction-TUI/codemode PRs.

Root cause

node inspect evaluates expressions in a VM context without an importModuleDynamically callback. A delayed import:

exec setTimeout(()=>import('node:fs'),0)

therefore rejects with:

ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING

The CLI also has a launcher/child topology. With a fixed NODE_OPTIONS=--inspect=..., the launcher previously claimed
the endpoint and cli-main inherited the same option, producing address already in use. The debugger attached to
the wrapper rather than the TUI child.

Behavior

Before spawning cli-main, the launcher now releases an active Inspector endpoint that came from inherited Node
startup options. The child can bind the same endpoint, so an existing fixed-port debugging command targets the
interactive process.

Recovery remains disabled unless the process starts with:

SENPI_RECOVER_INSPECTOR_VM_IMPORT=1 \
NODE_OPTIONS=--inspect=127.0.0.1:9229 \
senpi

The recovery predicate then requires:

• active Inspector endpoint
• unhandledRejection origin
• ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING
• Node's dynamic-import callback frame
• Inspector <anonymous> timer provenance

The opt-in is captured when the policy module loads, before runtime/extension loading. Later process.env mutation
cannot enable recovery. This explicit gate is necessary because Node does not expose a non-spoofable Inspector origin
on the global rejection.

RED -> GREEN

• RED: fixed-port child emitted address already in use
• RED: exact reported Inspector rejection exited through uncaughtException
• GREEN: deterministic parent -> child rebind on the same OS-assigned fixed port
• GREEN: explicit opt-in keeps the TUI alive with guidance
• GREEN: no opt-in, late env mutation, application VM, direct uncaughtException, and unrelated errors remain fatal

Verification

• focused regression: 5/5 passed
• coding-agent build: passed
• root npm run build: passed
• root npm run check: passed
• changed-file Biome: passed
• git diff --check: passed

The parallel coding-agent suite completed 4,509 passing tests and 32 skips, but three unrelated temporary-file writes
returned Linux errno -122 under concurrent load. Each affected test file passed directly afterward. A serial full
package run exceeded the 600-second command ceiling before summary.

Real-surface QA

• fixed-port fixpi --help: two sequential Inspector endpoints, no port conflict, exit 0
• real TUI + real node inspect, explicit opt-in: warning visible, process remained alive
• same real TUI without opt-in: exact reported error remained fatal, exit 1
• unrelated TypeError: remained fatal, exit 1
• browser-rendered xterm.js screenshot/transcript inspected
• isolated config/session/HOME, offline mode, no real provider or credential use
• all Inspector clients, PTYs, browsers, ports, and sandboxes cleaned

Review

Independent goal, code-quality, security, hands-on QA, and upstream-context reviewers returned PASS with no remaining
blockers.

---

Summary by cubic

Stops Node Inspector port conflicts and isolates the Inspector VM dynamic-import crash so sessions don’t die unexpectedly. The debugger now attaches to the TUI, and with an explicit opt-in the exact Inspector import rejection no longer kills the process.

• Bug Fixes

  • Launcher releases an inherited --inspect endpoint before spawning cli-main, letting the child rebind the same fixed port and avoiding “address already in use.”
  • Adds inspector-policy with an opt-in that keeps the TUI running only for ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING from Inspector eval (checked via origin and stack); shows a warning. All other errors remain fatal, and late env changes cannot enable recovery.

• Migration

  • To enable recovery while debugging: start with SENPI_RECOVER_INSPECTOR_VM_IMPORT=1 and NODE_OPTIONS=--inspect=127.0.0.1:<port>. Defaults remain unchanged.

^{Written for commit 06fad3d. Summary will update on new commits.}

[minpeter]

Superseded by #336, the verified patch-equivalent replacement based directly on current main. The replacement is an open draft, mergeable, one commit ahead/zero behind, with fresh focused test, build/check, and enabled/default real Inspector CLI QA evidence.