claude-code - 💡(How to fix) Fix [Bug] Bash tool: zsh command resolution fails after compound pipelines with while-read and &&-chains

Bug Description Title: Bash tool: zsh "command not found" for external commands after compound pipelines, even with full PATH

Summary After certain compound Bash commands (multi-stage pipe ending in while read, followed by &&-chained external commands), the post-&& commands fail with (eval):1: command not found: <cmd> even though $PATH is fully populated and the commands resolve fine in direct probes. Substituting absolute paths (/bin/ls vs ls) makes the same command work — so PATH-the-variable is correct, but the shell's command-lookup machinery is broken in the post-pipeline eval context.

Environment

• macOS, zsh 5.9
• Claude Code CLI (current build)
• Shell: /bin/zsh (interactive zsh; verified $SHELL, $0, $ZSH_VERSION)

Minimal repro (fails) cd /.claude && true ; printf 'X/.claude/doctrine/a.mdX\n' | sort -u |
sed 's/X//g; s|~/|/Users/joewolf/|' |
while read path; do if [ -e "$path" ]; then echo "OK"; else echo "MISSING"; fi done && ls doctrine/ | wc -l

Output: MISSING (eval):1: command not found: ls (eval):1: command not found: wc

Same command with /bin/ls and /usr/bin/wc substituted — WORKS: ... done && /bin/ls doctrine/ | /usr/bin/wc -l

Output: MISSING

Diagnostic findings

1. $PATH is fully populated in every direct probe (top-level, inside while-read body, after &&-chain, inside command substitution). Full PATH includes /usr/bin and /bin where ls/wc/basename live.
2. which ls, which basename, which wc all resolve to /bin/ls, /usr/bin/basename, /usr/bin/wc in direct probes.
3. The error prefix (eval):1: is zsh's specific format for commands run through eval — the post-pipeline &&-chained commands ARE being eval'd somewhere in the tool chain, not run directly.
4. Absolute paths bypass the broken lookup and work normally → confirms PATH-the-variable is fine, but PATH-based command resolution is broken in that eval context.
5. Likely cause: zsh command hash-table is in a degraded/cleared state in the re-eval context, but $PATH itself is preserved. zsh normally hashes PATH-directory contents on first lookup; if hash is invalidated without rehash, subsequent PATH-relative commands fail until rehash.

Why non-deterministic-looking on first bisection Structural triggers don't bisect cleanly — minor differences in command structure (one sed substitution vs two, presence of ~/ in input, etc.) flip between working and failing in confusing ways. This suggests the trigger isn't purely structural in zsh — it's likely in how Claude Code's Bash tool processes the command string before passing it to zsh (token length threshold, sandbox heuristic, hash-eviction timing, or hook intercepting+re-eval'ing parts of compound commands).

Smoking-gun probe pair (deterministic) Same command, two outcomes — only difference is bare command names vs absolute paths:

# FAILS:
... | while read path; do ...; done && ls doctrine/ | wc -l

# WORKS:
... | while read path; do ...; done && /bin/ls doctrine/ | /usr/bin/wc -l

Workarounds (in order of preference)

1. Absolute paths for external commands after long pipelines
2. Split compound commands into separate Bash tool calls
3. Avoid while read followed by &&-chains with external commands in a single Bash invocation

Severity Low (workaround is trivial), but high "wasted-debugging-time" potential — the failure mode looks like a PATH bug but isn't, and the non-deterministic- looking bisection chews through context budget before the smoking-gun absolute- path test reveals the real cause.

Repro file count: tested against 14 probes; both reproducible failures and working variants captured. Happy to share the full probe transcript if useful.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.143
• Feedback ID: 521ccab5-059c-4f7f-b447-b58d2c111a34

Errors

[{"error":"Error: Stream idle timeout - partial response received\n    at DSK (/$bunfs/root/src/entrypoints/cli.js:9089:15603)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-16T14:32:45.578Z"},{"error":"Error: The socket connection was closed unexpectedly. For more information, pass `verbose: true` in the second argument to fetch()\n    at from (/$bunfs/root/src/entrypoints/cli.js:118:7862)\n    at <anonymous> (/$bunfs/root/src/entrypoints/cli.js:126:12898)\n    a…

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