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mcp: on macOS and Linux the server warns that every tool will fail, though the tools work #1357
Description
On macOS and Linux, axiomcode mcp always prints this warning to stderr:
axiomcode mcp: AXIOMCODE_BASH is set to bash, which does not exist.
The server starts, but every tool will say it cannot run the CLI.
The warning is false: tools/call returns correct answers. An MCP client that shows server stderr tells the user the tools are broken when they work.
Cause. On a non-Windows platform findBash() returns the bare name bash, and bin/axiomcode.js exports it as AXIOMCODE_BASH=bash. axiomcode mcp then goes through mcp/launch.js, which calls findBash() again. It sees the override and checks fs.existsSync("bash"), which is resolved against the working directory, so the check fails. server.py still inherits AXIOMCODE_BASH=bash and runs normally.
Fix. Test for existence only when the override is a path, or have bin/axiomcode.js export AXIOMCODE_BASH only when it holds an absolute path.
Found by an end-to-end run of 0.1.1 on macOS and Linux. Windows is not affected, because there the value is an absolute path.
Activity
swapnilpaliwal-sd commentedon Oct 8, 2026
Still reproduces on
apps/integration-0.1.9(2026-10-08), and two external evaluations reported it independently on 0.1.8.Reproduction (macOS): start
axiomcode mcp, sendinitialize: the server answers, and stderr saysCause, confirmed:
bin/axiomcode.jsexportsAXIOMCODE_BASH=bash(the bare namefindBash()returns on POSIX);mcp/launch.jscallsfindBash()again, which checks the override withfs.existsSync, a file-path test, so a program name always "does not exist".Fix: a bare name is resolved on PATH; a path is checked as written; either one missing remains an error (exit 127). Regression test in
tests/mcp.pyfails on the current code with the reported message and passes with the fix. PR to follow.swapnilpaliwal-sd commentedon Oct 8, 2026
Fixed by #1867, merged into
apps/integration-0.1.9(e0e8450); ships with 0.1.9.mcp: a bare AXIOMCODE_BASH is a program on PATH, not a missing file (A…