From 865cebe6ed162c410103ad39bd31add0830e79f2 Mon Sep 17 00:00:00 2001
From: skytow <acepci@gmail.com>
Date: Sun, 31 May 2026 03:10:40 -0400
Subject: [PATCH] Fix sed-substitution of {{TOPIC}} mangling/breaking on
 special chars

start-loop.sh injected the user-provided topic into the plan-mode prompt
templates via `sed "s|{{TOPIC}}|$TOPIC|g"`. In a sed replacement three
characters are special: `&` (the whole matched text, i.e. `{{TOPIC}}`),
the `|` delimiter, and `\`. So a topic like "Paywall & monetization"
rendered as "Paywall {{TOPIC}} monetization", and a topic containing `|`
crashed sed outright ("bad flag in substitute command").

Escape `\`, `&`, and `|` (and collapse newlines, since sed is
line-oriented) into SED_SAFE_TOPIC before substitution. REVIEW_ID and
MAX_ROUNDS are a generated id and an integer, so they need no escaping.

Verified: a topic with `& | \` now round-trips verbatim; bash -n passes;
doctor + smoke test (74/74) still green. stop-hook.sh is unaffected (it
expands $TOPIC via bash, not sed).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 plugins/claudex/scripts/start-loop.sh | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/plugins/claudex/scripts/start-loop.sh b/plugins/claudex/scripts/start-loop.sh
index 862ba16..d8b5701 100755
--- a/plugins/claudex/scripts/start-loop.sh
+++ b/plugins/claudex/scripts/start-loop.sh
@@ -185,6 +185,14 @@ decision_signal: none"
 claudex_state_write "$STATE_FILE" "$STATE_CONTENT" || exit 3
 claudex_lock_write "$LOCK_FILE" || exit 3
 
+# {{TOPIC}} is substituted into the prompt templates via sed below. The topic is
+# user-provided and may contain characters that are special in a sed replacement:
+# backslash, "&" (means "the whole matched text", i.e. "{{TOPIC}}"), and the "|"
+# delimiter. Escape all three so the literal topic is inserted verbatim, and
+# collapse newlines since sed operates line-by-line. (REVIEW_ID and MAX_ROUNDS are
+# a generated id and an integer, so they need no escaping.)
+SED_SAFE_TOPIC="$(printf '%s' "$TOPIC" | tr '\n\r' '  ' | sed -e 's/[\\&|]/\\&/g')"
+
 # Print initial instructions to stdout. Claude will read these.
 case "$MODE" in
   plan)
@@ -196,13 +204,13 @@ case "$MODE" in
       echo "Source: existing PLAN.md (--from-draft)"
       echo ""
       cat "$CLAUDE_PLUGIN_ROOT/scripts/prompts/plan-mode-from-draft.md" 2>/dev/null \
-        | sed -e "s|{{TOPIC}}|$TOPIC|g" -e "s|{{REVIEW_ID}}|$REVIEW_ID|g" -e "s|{{MAX_ROUNDS}}|$MAX_ROUNDS|g"
+        | sed -e "s|{{TOPIC}}|$SED_SAFE_TOPIC|g" -e "s|{{REVIEW_ID}}|$REVIEW_ID|g" -e "s|{{MAX_ROUNDS}}|$MAX_ROUNDS|g"
     else
       echo ""
       echo "Round 1 - drafting plan."
       echo ""
       cat "$CLAUDE_PLUGIN_ROOT/scripts/prompts/plan-mode-init.md" 2>/dev/null \
-        | sed -e "s|{{TOPIC}}|$TOPIC|g" -e "s|{{REVIEW_ID}}|$REVIEW_ID|g"
+        | sed -e "s|{{TOPIC}}|$SED_SAFE_TOPIC|g" -e "s|{{REVIEW_ID}}|$REVIEW_ID|g"
     fi
     ;;
   review)