Codex, Antigravity, and Devin launch their agent-hook `command` as a program
(argv[0]), not through cmd.exe. PR #8430 changed wrapWindowsCmdHookCommand to
emit an `if exist "path\." (drain) else if exist "path" (call "path") else
(drain)` compound whose argv[0] is the cmd builtin `if` — unspawnable — so every
Codex/Antigravity/Devin hook (SessionStart, UserPromptSubmit, Stop, ...) failed
with "hook exited with code 1" on Windows starting in v1.4.138.
Revert the cmd-safe fast path to the bare, directly-spawnable .cmd path (the
proven pre-#8430 form). A cmd-builtin drain and direct-spawnability are mutually
exclusive, and nesting cmd.exe /d /c breaks large-payload draining; the
missing-script stdin drain stays on the encoded-PowerShell fallback (used for
spaced/non-ASCII paths). Upgrades self-heal on first launch: startup install()
unconditionally rewrites the command and Codex trust entry, sweeping the old
compound form.
Add a platform-independent regression guard (launcher must resolve to a real
file, never a cmd-builtin fragment), update the lifecycle test + docs, and fix a
stale Devin comment.
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