fix(edit): taught markdown bullet escaping

Clarified hashline minus-row errors and model-facing prompt examples so Markdown list rows use the + body-row prefix instead of triggering write fallbacks.

Fixes #4179

docs/tools/edit.md

@@ -43,7 +43,7 @@ Patch language inside `input`:
   - Every body row is `+TEXT`; `+` alone adds a blank line.
   - `DEL` never has body rows.
   - There is no repeat row kind. To keep a line, leave it out of every range; split edits into multiple hunks when needed.
-  - `-` rows are invalid. Literal text beginning with `-` or `+` must be written as `+-text` / `++text`.
+  - `-` rows are invalid. Literal Markdown bullets or text beginning with `-` / `+` must be written as `+- item` / `++ item`.
 
 Anchors come from `read`/`grep` output. `read` emits a `[PATH#TAG]` header from the session snapshot store and lines as `LINE:TEXT`; copy the header into the edit section and copy only the line number into hunk headers.
 
@@ -165,7 +165,7 @@ DEL 20
 - Stray payload line:
   - `line N: payload line has no preceding hunk header. Use \`SWAP N.=M:\`, \`DEL N.=M\`, or \`INS.PRE|POST|HEAD|TAIL:\` above the body. Got "...".`
 - Minus row:
-  - ``line N: `-` rows are not valid; the range already names the lines being changed. For a literal `-` line, write `+-…`.``
+  - ``line N: `-` rows are not valid; the range already names the lines being changed. For Markdown bullets or other literal `-` lines, prefix the literal row with `+`: `+- item`.``
 - Empty body-bearing hunk:
   - `line N: \`INS\` needs at least one \`+TEXT\` body row.`
   - `line N: \`SWAP.BLK N:\` needs at least one \`+TEXT\` body row. To delete a block, use \`DEL.BLK N\`.`

packages/coding-agent/CHANGELOG.md

@@ -21,6 +21,7 @@
 - Fixed RPC mode abort_bash being blocked by running bash commands by dispatching bash in the background.
 - Fixed task.maxConcurrency and task.maxRecursionDepth limits being bypassed by sub-spawn paths, ensuring limits are dynamically resized and respected.
 - Fixed the edit tool inflating session files by pruning extremely large file snapshots from tool-result details.
+- Fixed edit-tool Markdown list guidance so hashline parser errors and the model-facing prompt teach `+- item` escaping instead of steering agents toward full-file `write` fallbacks. ([#4179](https://github.com/can1357/oh-my-pi/issues/4179))
 - Fixed workstation OS detection rendering "Kernel: unknown" on macOS 15+.
 - Fixed /copy code and /copy cmd commands being treated as normal prompts instead of copying the requested blocks.
 - Fixed interactive bash status line not updating after directory changes (cd).

packages/hashline/CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - Fixed an issue where snapshot tag collisions could cause line-anchored edits to be incorrectly applied to unrelated content.
 - Fixed tracking of edit anchors when earlier in-session insertions or deletions shift unchanged target lines.
+- Fixed hashline edit guidance for Markdown list rows by teaching `+- item` escaping in the model prompt and minus-row parser error. ([#4179](https://github.com/can1357/oh-my-pi/issues/4179))
 
 ## [16.2.8] - 2026-06-30
 

packages/hashline/src/messages.ts

@@ -54,7 +54,7 @@ export const BARE_BODY_AUTO_PIPED_WARNING =
 
 /** Unified-diff-style `-` row in a hunk body. */
 export const MINUS_ROW_REJECTED =
-	"`-` rows are not valid; the range already names the lines being changed. For a literal `-` line, write `+-…`.";
+	"`-` rows are not valid; the range already names the lines being changed. For Markdown bullets or other literal `-` lines, prefix the literal row with `+`: `+- item`.";
 
 /** Replace hunk with no body. */
 export const EMPTY_REPLACE = `\`SWAP N${HL_RANGE_SEP}M:\` needs at least one \`+TEXT\` body row. To delete lines, use \`DEL N${HL_RANGE_SEP}M\`.`;

packages/hashline/src/prompt.md

@@ -19,7 +19,7 @@ Single line: `SWAP N.=N:` / `DEL N`. The range is the ORIGINAL lines you touch;
 </ops>
 
 <body-rows>
-Body rows appear only under a `:` header. Every body row is `+TEXT` — add a literal line `TEXT`, verbatim (leading whitespace kept); `+` alone adds a blank line. No other row kind. NEVER write `-old` or a bare/context line. To keep a line, leave it out of every range. To insert a literal line starting with `-` or `+`, prefix it: `+-x`, `++x`.
+Body rows appear only under a `:` header. Every body row is `+TEXT` — add a literal line `TEXT`, verbatim (leading whitespace kept); `+` alone adds a blank line. No other row kind. NEVER write `-old` or a bare/context line. To keep a line, leave it out of every range. Literal lines starting with `-`/`+` still need the body prefix: Markdown `- item` → `+- item`, `+ item` → `++ item`.
 </body-rows>
 
 <rules>
@@ -103,6 +103,14 @@ INS.TAIL:
 +greet("everyone")
 ```
 
+Insert Markdown bullets — the leading `+` is the body-row marker; the file receives `- task`:
+```
+[PLAN.md#A1B2]
+INS.POST 2:
++- task
++  - nested task
+```
+
 Replace the whole `greet` function block — `SWAP.BLK 1:` resolves lines 1–3 (the `def` header through `print(msg)`); line 4 is a separate statement and stays:
 ```
 [greet.py#A1B2]
@@ -160,5 +168,5 @@ INS.POST 3:
 If you remember nothing else:
 1. RE-GROUND AFTER EVERY EDIT. Every apply mints a fresh `#TAG` and renumbers — take the next edit's numbers from the edit response or a fresh `read`. Stale tag or surprise? STOP, re-`read`.
 2. RANGES ARE TIGHT. Cover only lines that change; a stale wide range shreds everything it spans. Whole construct → `SWAP.BLK N`.
-3. THE BODY IS THE FINAL CONTENT. Only `+TEXT` rows; never `-old`/context lines. The range does the deleting.
+3. THE BODY IS THE FINAL CONTENT. Every body row starts with `+`; Markdown bullets use `+- item`, not `- item`.
 </critical>

packages/hashline/test/leniency.test.ts

@@ -166,12 +166,16 @@ describe("hashline body contracts", () => {
 		expect(applyEdits(FILE, result.edits).text).toBe('a\n1: "one",\n2: "two",\nd\ne');
 	});
 
-	it("rejects `-` body rows with a teaching error", () => {
-		expect(() => parsePatch("SWAP 2.=2:\n-old\n+new")).toThrow(/`-` rows are not valid/);
+	it("rejects `-` body rows with Markdown bullet escape guidance", () => {
+		expect(() => parsePatch("SWAP 2.=2:\n-old\n+new")).toThrow(
+			/Markdown bullets or other literal `-` lines.*`\+- item`/,
+		);
 	});
 
-	it("allows literal text that begins with `-` or `+` when prefixed with `+`", () => {
-		expect(applyPatch(FILE, "SWAP 2.=2:\n+-literal\n++plus")).toBe("a\n-literal\n+plus\nc\nd\ne");
+	it("allows literal Markdown bullets and plus-prefixed text when prefixed with `+`", () => {
+		expect(applyPatch(FILE, "SWAP 2.=2:\n+- item\n+  - nested\n++plus")).toBe(
+			"a\n- item\n  - nested\n+plus\nc\nd\ne",
+		);
 	});
 
 	it("treats empty replace as delete and still rejects empty insert", () => {