From 58d7723c7972de468a537eb57f07cad7f5019902 Mon Sep 17 00:00:00 2001
From: Aaron Z <mj.aaron.chu@gmail.com>
Date: Thu, 14 May 2026 10:03:33 +0800
Subject: [PATCH 1/2] fix(coding-agent/edit): add format reminder to hashline
 prompt to prevent anchor+content on same line

Models frequently write '+ ANCHOR| CONTENT' instead of '+ ANCHOR'
followed by '~CONTENT' on the next line. Add a compact FORMAT block
between </ops> and <rules> with a WRONG/RIGHT example that directly
addresses this failure mode.
---
 packages/coding-agent/src/prompts/tools/hashline.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/packages/coding-agent/src/prompts/tools/hashline.md b/packages/coding-agent/src/prompts/tools/hashline.md
index d8380db46..9ca59b604 100644
--- a/packages/coding-agent/src/prompts/tools/hashline.md
+++ b/packages/coding-agent/src/prompts/tools/hashline.md
@@ -14,6 +14,18 @@ Purely textual format. The tool has NO awareness of language, indentation, brack
 = A..B           replace the range with payload `{{hsep}}TEXT` lines, or with one blank line if no payload follows.
 </ops>
 
+<format-reminder>
+Each op line is ONE of:
+  + ANCHOR        ← nothing after the anchor! Content goes on ~ lines below.
+  < ANCHOR        ← same rule.
+  - A..B          ← no content needed (deletion).
+  = A..B          ← followed by ~TEXT payload lines.
+
+WRONG:  + 129pg|                 some code here
+RIGHT:  + 129pg
+        ~                some code here
+</format-reminder>
+
 <rules>
 - Every line of inserted/replacement content MUST be emitted as a payload line starting with `{{hsep}}`.
 - `{{hsep}}` is syntax, not content. The inserted text begins after the first `{{hsep}}`; use a bare `{{hsep}}` to insert a blank line.

From d62480dc6524116d7aed26150baefe03d4ea48d5 Mon Sep 17 00:00:00 2001
From: can1357 <me@can.ac>
Date: Thu, 14 May 2026 05:00:10 +0200
Subject: [PATCH 2/2] fix(edit): slim format-reminder and use configured
 separator

- Drop duplicated op listing from the reminder; <ops> already defines
  the four shapes one block above.
- Replace hardcoded `~` with the {{hsep}} helper so the reminder
  tracks PI_HL_SEP / HL_EDIT_SEP overrides, matching the rest of
  hashline.md and addressing Codex review on #1063.
- Shrink the WRONG/RIGHT example (smaller anchor, no padding runs)
  since the reminder's only job is contrasting on-line vs next-line
  payload placement.
---
 packages/coding-agent/src/prompts/tools/hashline.md | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/packages/coding-agent/src/prompts/tools/hashline.md b/packages/coding-agent/src/prompts/tools/hashline.md
index 9ca59b604..8b32ac857 100644
--- a/packages/coding-agent/src/prompts/tools/hashline.md
+++ b/packages/coding-agent/src/prompts/tools/hashline.md
@@ -8,6 +8,7 @@ Purely textual format. The tool has NO awareness of language, indentation, brack
 
 <ops>
 @@ PATH          header: subsequent ops apply to PATH
+Each op line is ONE of:
 + ANCHOR         insert lines AFTER  the anchored line (or EOF); payload follows as `{{hsep}}TEXT` lines
 < ANCHOR         insert lines BEFORE the anchored line (or BOF); payload follows as `{{hsep}}TEXT` lines
 - A..B           delete the line range (inclusive).
@@ -15,15 +16,11 @@ Purely textual format. The tool has NO awareness of language, indentation, brack
 </ops>
 
 <format-reminder>
-Each op line is ONE of:
-  + ANCHOR        ← nothing after the anchor! Content goes on ~ lines below.
-  < ANCHOR        ← same rule.
-  - A..B          ← no content needed (deletion).
-  = A..B          ← followed by ~TEXT payload lines.
+Op lines carry no content — payload goes on the next line.
 
-WRONG:  + 129pg|                 some code here
-RIGHT:  + 129pg
-        ~                some code here
+WRONG: + 5pg| some code
+RIGHT: + 5pg
+       {{hsep}} some code
 </format-reminder>
 
 <rules>