Incompatibility with Z shell and direnv: `Invalid session ID ...`

[peterbecich]

Describe the bug

This issue is related to Z shell and https://github.com/direnv/direnv, and possibly https://github.com/nix-community/nix-direnv.

I think the issue is completely unrelated to Nix.

I have tested both Copilot CLI 0.0.365 and 0.0.367.

The error is:

   Invalid session ID: 1. Please supply a valid session ID to read ...

It occurs in these cases:

• shell is Z shell; then direnv allow to configure the shell; then copilot
  or
• nix develop -c /bin/zsh; then copilot

It does not occur when:

• shell is Z shell and not using direnv (direnv revoke); then copilot
  or
• shell is bash; then direnv allow to configure the shell; then copilot
  or
• shell is arbitrary; then nix develop to open Nix shell (default is bash); then copilot

Therefore, I suspect the issue is the combination of Z shell and direnv.

The issue #640 does not mention direnv, hence the new issue.

Workaround

• Enter the nix develop shell (or nix-shell); this is a bash shell by default
• then start copilot

or

• bash
• then direnv allow

The valid session ID error should not happen.

Affected version

No response

Steps to reproduce the behavior

No response

Expected behavior

No response

Additional context

No response

[mknudsen]

Can confirm this is an issue with direnv, zsh, nix on macos.

copilot --version
0.0.368-0
Commit: 8d0421f

[guyhuang]

Same on zsh, macos without direnv, only in gemini pro 3：
zsh --version
zsh 5.9 (arm64-apple-darwin25.0)
copilot --version
0.0.367
Commit: 9b421b4
sw_vers
ProductName: macOS
ProductVersion: 26.1
BuildVersion: 25B78

Read shell output Invalid session ID: 02222222-3333-4444-5555-666666666666. Please supply a valid session ID to read output from.

[arunoruto]

I have the same issue with the following setup:

• Running NixOS (25.11)
• Using direnv with nix-direnv
• I am entering a devenv enviorment
• I am using fish as my shell, but copilot wants to use bash.
  It reports that read_bash says that the session ID is invalid and list_bash shows no active sessions.

[RohanM]

I ran into this issue, and switching to bash didn't resolve it. However, uninstalling nix-direnv and using plain direnv with nix solved the problem for me.

[WhiteBlackGoose]

Hitting the same issue (NixOS 25.11). With both fish and bash

[PureWeen]

I've started hitting this more frequently with the latest release of copilot
I'm on a mac using zsh

0.0.377
Commit: 4a0b36b

[WhiteBlackGoose]

The issue is still there, 0.0.387

P. S. 0.402 too
P.P.S.: adding bashInteractive to the flake like advised below fixed it

[landure]

the issue also occurs with bash, direnv, and devenv (https://devenv.sh/).
I've tried with direnv deny . and direnv disallow . , and running copilot in a devenv shell and the issue is still present.

copilot works fine in a standard bash shell.

This incompatibility with devenv shell is recent.

[bdimcheff]

After extensive arguing with copilot, I found the issue occurs for me when Copilot CLI finds a nix-wrapped bash (/nix/store/.../bash) first in PATH instead of system /bin/bash.

On a mac with fish, devenv, direnv, and copilot 0.0.405, if I manually prepend /bin:/usr/bin to PATH before launching copilot it seems to work, but this is fairly annoying. Not sure what nix bash is doing that would cause this.

I tried clearing DIRENV_*, DEVENV_*, and NIX_* environment variables and it didn't help.