feat(hashline-edit): add anchor insert modes and strict insert validation

[code-yeongyu]

Summary

• Add insert_before and insert_between hashline edit operations with dual-anchor validation.
• Enforce non-empty insert payloads for all insert operations, align with strict empty-insert error behavior.
• Improve hash mismatch errors with >>> context output, add edit dedup/noop reporting, and support delete/rename edit modes in tool args.
• Add streaming hashline formatters and expand tests for new operations and error behavior.

Verification

• bun test src/tools/hashline-edit/edit-operations.test.ts src/tools/hashline-edit/validation.test.ts src/tools/hashline-edit/hash-computation.test.ts src/tools/hashline-edit/tools.test.ts
• bun run typecheck
• bun run build

---

Summary by cubic

Adds precise anchor insert modes with strict validation and improved mismatch context, plus consistent chunked hashline streaming. Reports dedup/no-op edits and supports file delete/rename.

• Bug Fixes
  • Fixed anchor-echo stripping for single-line inserts and boundary-only insert_between payloads (empty inserts now error).
  • Aligned streamHashLines* with formatHashLines for empty inputs using a shared chunk formatter for consistent chunking.
  • Added regression tests for the above cases.

^{Written for commit 7e68690. Summary will update on new commits.}

[cubic-dev-ai]

5 issues found across 13 files

Confidence score: 3/5

• src/tools/hashline-edit/edit-text-normalization.ts has concrete logic bugs (boundary-only payload length check and early return) that can leave echo artifacts or duplicate a line, which is user-visible behavior.
• These are higher-severity issues (6–7/10) with high confidence, so there is some regression risk despite the limited scope.
• Pay close attention to src/tools/hashline-edit/edit-text-normalization.ts - normalization edge cases around boundary/anchor echoes.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/tools/hashline-edit/hash-computation.ts">

<violation number="1" location="src/tools/hashline-edit/hash-computation.ts:75">
P3: Stateful chunking logic (`pushLine` and `flush`) is heavily duplicated between stream formatters.</violation>

<violation number="2" location="src/tools/hashline-edit/hash-computation.ts:131">
P2: `streamHashLinesFromUtf8` handles empty streams inconsistently compared to `formatHashLines`.</violation>

<violation number="3" location="src/tools/hashline-edit/hash-computation.ts:205">
P2: `streamHashLinesFromLines` handles empty iterables inconsistently compared to `formatHashLines`.</violation>
</file>

<file name="src/tools/hashline-edit/edit-text-normalization.ts">

<violation number="1" location="src/tools/hashline-edit/edit-text-normalization.ts:60">
P2: Early return prevents stripping a single-line anchor echo, bypassing empty-insert validation and duplicating the line.</violation>

<violation number="2" location="src/tools/hashline-edit/edit-text-normalization.ts:77">
P1: Incorrect length check prevents stripping of trailing boundary echo when the payload consists only of the boundaries.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

1 issue found across 5 files (changes from recent commits).

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/tools/hashline-edit/edit-text-normalization.ts">

<violation number="1" location="src/tools/hashline-edit/edit-text-normalization.ts:60">
P1: `stripInsertBeforeEcho` still uses `newLines.length <= 1` and was missed in this strict validation update. An `insert_before` payload containing only an echo line will duplicate the anchor instead of erroring out.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P1: stripInsertBeforeEcho still uses newLines.length <= 1 and was missed in this strict validation update. An insert_before payload containing only an echo line will duplicate the anchor instead of erroring out.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At src/tools/hashline-edit/edit-text-normalization.ts, line 60:

<comment>`stripInsertBeforeEcho` still uses `newLines.length <= 1` and was missed in this strict validation update. An `insert_before` payload containing only an echo line will duplicate the anchor instead of erroring out.</comment>

<file context>
@@ -57,7 +57,7 @@ export function restoreLeadingIndent(templateLine: string, line: string): string
 
 export function stripInsertAnchorEcho(anchorLine: string, newLines: string[]): string[] {
-  if (newLines.length <= 1) return newLines
+  if (newLines.length === 0) return newLines
   if (equalsIgnoringWhitespace(newLines[0], anchorLine)) {
     return newLines.slice(1)
</file context>