fix(ralph-loop): session isolation bypass when CLAUDE_CODE_SESSION_ID is empty

[pure-maple]

Summary

• Fix Ralph Loop cross-session interference when CLAUDE_CODE_SESSION_ID is empty in Bash execution context
• Fix completion promise false positive when no <promise> tag exists in output

Problem

When CLAUDE_CODE_SESSION_ID is not set (which happens in the Bash tool execution context), setup-ralph-loop.sh writes an empty session_id to the state file. The stop hook's isolation check ([[ -n "$STATE_SESSION" ]]) treats empty as "legacy" and falls through, causing the Ralph Loop to intercept all sessions in the same project directory — not just the session that started it.

In our case, a Ralph Loop started in a learning-system research session leaked into 2 unrelated sessions (work tasks and a migration task), burning hundreds of conversation turns before being noticed.

Additionally, the Perl -pe substitution for <promise> tag extraction preserves the full input text when no tag is found. If the raw assistant output happens to equal the completion promise string, the loop exits prematurely (false positive).

Fix

setup-ralph-loop.sh (line 144):

• Fallback to uuidgen when CLAUDE_CODE_SESSION_ID is empty, ensuring session_id is always non-empty

stop-hook.sh (lines 27-35):

• Treat empty STATE_SESSION as invalid — exit 0 instead of falling through
• Split compound conditional into two clear checks for readability

stop-hook.sh (line 136):

• Replace perl -pe substitution with perl -ne extraction that only prints content when <promise> tag actually exists

Test plan

• Start Ralph Loop in session A, verify session B in same project is not intercepted
• Start Ralph Loop with CLAUDE_CODE_SESSION_ID unset, verify fallback UUID is written
• Verify completion promise detection still works with <promise> tags
• Verify no false positive when output contains promise text without <promise> tags

[github-actions]

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[Copilot]

Pull request overview

Fixes session isolation and completion-promise detection in the Ralph Loop plugin to prevent cross-session interception and premature loop termination when <promise> tags are absent.

Changes:

• Ensure session_id in Ralph Loop state is never empty by generating a fallback ID during setup.
• Tighten Stop-hook session isolation logic to avoid intercepting when isolation can’t be enforced.
• Update <promise> extraction to return empty output when no <promise> tag exists (prevents false positives).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
plugins/ralph-loop/scripts/setup-ralph-loop.sh	Writes a non-empty session_id into the Ralph Loop state file using a UUID fallback.
plugins/ralph-loop/hooks/stop-hook.sh	Enforces session isolation more explicitly and makes <promise> extraction non-matching-safe.

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[Copilot]

session_id is written from $CLAUDE_CODE_SESSION_ID, but when that variable is empty you now generate a new UUID. The Stop hook later enforces isolation by comparing STATE_SESSION (from this file) to HOOK_INPUT.session_id; if $CLAUDE_CODE_SESSION_ID is not the same identifier as HOOK_INPUT.session_id (or is unset in the Bash tool context as described), the generated UUID will never match any real session and the loop will never intercept even the session that started it. Consider obtaining the same session identifier the Stop hook uses (e.g., pass it into this script explicitly), or change the Stop hook to "claim"/persist the first non-empty HOOK_INPUT.session_id into the state file instead of generating a random value here.

[Copilot]

Using echo "$LAST_OUTPUT" can mis-handle edge cases where the output begins with -n/-e (option parsing) or contains backslash escapes, which can alter the string being scanned for <promise> and lead to incorrect completion detection. Prefer printf '%s' "$LAST_OUTPUT" (or an equivalent non-echo write) when feeding arbitrary text into Perl.