Windows support for the embedded Claude session (ConPTY) - #7
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The Claude panel was POSIX-only and died on Windows with "File not found" before the CLI even started. Three win32 branches, POSIX path untouched: - which(): resolve via where.exe, preferring .exe/.cmd/.bat — npm puts an extensionless sh shim first, which Windows cannot exec - spawn: no bash watchdog wrapper; .cmd/.bat shims route through cmd.exe /c under ConPTY. Closing the pty tears down the attached console tree, so a hard Electron death still takes claude with it - closeSession(): pty.kill() instead of process.kill(-pid, SIGHUP) — negative-pid group signals throw on Windows Tested on Windows 11 (26200), Node 24, claude CLI 2.1.233: panel opens, all six kadr_* MCP tools reachable from the embedded session. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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…lpFreedom#7 in view PR HelpFreedom#7 (simplaerai-sv, «Windows support for the embedded Claude session») solves the same failure on the v0.3 base. This compares the two and takes the one idea from it worth taking. ### Taken: the explicit cmd.exe route `winLaunch` now starts a `.cmd`/`.bat` launcher — npm's `claude.cmd` shim — through `%ComSpec%` itself instead of letting CreateProcess supply the interpreter. Two things come with that. `/d` skips the registry AutoRun (this machine has clink there; a conda hook is the other usual tenant), which otherwise runs inside the panel's cmd.exe and can print into it. And the quoting becomes ours: `/s` plus an outer pair of quotes around the whole line, which keeps a launcher path with a space in it whole. That last part is where PR HelpFreedom#7's version breaks. It spawns `cmd.exe /c "<shim>" args...` bare, and cmd's parser strips the first and the last quote of its command when the first character is a quote — so `"C:\Users\Jane Doe\AppData\Roaming\npm\claude.cmd" --mcp-config ...` becomes `C:\Users\Jane Doe\...` and cmd stops at `C:\Users\Jane`. A user name with a space is not exotic. Verified with a shim in a directory with a space: bare `/c` fails as described, the outer-quoted form and the implicit CreateProcess form both deliver every argument intact, inner quotes and non-ASCII included. ### Not taken: `where.exe` PR HelpFreedom#7 resolves the CLI with `where.exe` and prefers an `.exe`/`.cmd`/`.bat` hit, falling back to the first line — which is npm's extensionless sh shim, the file ConPTY cannot start. The PATH walk here uses PATHEXT, so that shim is never a candidate; it searches the SESSION's PATH, which claude-env.json may extend; and it checks `~/.local/bin`, the native installer's directory, for an editor launched from a desktop entry whose PATH has not caught up. It also spawns no helper process. Session teardown is the same in both: `pty.kill()` on Windows, node-pty's ConPTY kill enumerating the console's process list. ### Verification, on the real UI this time Windows 11, claude 2.1.265 from npm, the panel driven by hand: - open → one `cmd.exe /d /s /c "…claude.CMD …"` and one claude.exe; - close → nothing left; close-and-reopen in quick succession → exactly one tree; quit the editor with the panel open → nothing left; - `/mcp` inside the panel: kadr connected, 13 tools; the same 13 over a stdio client spawning mcp-bridge.cjs like claude does; kadr_state and kadr_eval answer; /eval refuses a request without the token and one carrying an Origin (403 both); - close/reopen regenerates kadr-mcp.json with a fresh bridge port; - the trust dialog that appears with no project open is the CLI's own: the panel starts in the home directory then, and the CLI does not persist trust for it even when run from a plain terminal. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Problem
On Windows the Claude panel dies immediately with
Error: File not found— the session spawn path is POSIX-only:a
/bin/bashwatchdog wrapper,/bin/sh command -v, and negative-pidgroup signals.
Changes
One file,
electron/claude.ts, win32 branches only — the POSIX path isuntouched:
which(): resolve viawhere.exe, preferring.exe/.cmd/.bat. npminstalls an extensionless sh shim next to
claude.cmdand lists itfirst; Windows cannot exec it.
.cmd/.batshims are routed throughcmd.exe /c(a shim cannot beCreateProcess'd directly). Closing thepty tears down the attached ConPTY console tree, so a hard Electron
death still takes claude with it — the guarantee the wrapper provides
on POSIX.
killSession():pty.kill()instead ofprocess.kill(-pid, SIGHUP)—negative-pid group signals are a POSIX concept and throw on Windows.
Tested
Windows 11 (build 26200), Node 24, claude CLI 2.1.233:
kadr_*MCP tools are reachable from the embedded sessionkadr-mcp.jsonwith a fresh bridge portHonest caveat: that run was against the v0.3.0 base. The branch has
since been rebased onto v0.5.1, so it now sits on top of the session
generation/serialization rework and
sessionEnv(). The merge resolutionkeeps both — upstream session identity, plus the win32 spawn branch —
and
tsc -p tsconfig.node.jsonis clean, but the rebased build has notbeen re-run on Windows yet. Happy to confirm before you merge.
No file overlap with the other open Windows PR (#9, which fixes
npm installand the dev-server bind), nor with #3 (macOS) or #5 (NixOS).🤖 Generated with Claude Code