Patches files given diff hunks. Primary tool for existing-file edits.

**Hunk Headers:** - `@@` — bare header when context lines unique - `@@ $ANCHOR` — anchor copied verbatim from file (full line or unique substring) **Anchor Selection:** 1. Otherwise choose highly specific anchor copied from file: - full function signature - class declaration - unique string literal/error message - config key with uncommon name 2. On "Found multiple matches": add context lines, use multiple hunks with separate anchors, or use longer anchor substring **Context Lines:** Use enough ` `-prefixed lines to make match unique (usually 2–8) When editing structured blocks (nested braces, tags, indented regions), include opening and closing lines so edit stays inside block ```ts // Input is { path: string, edits: Entry[] }. `path` is required and applies to every entry. type Entry = // Diff is one or more hunks for the top-level path. // - Each hunk begins with "@@" (anchor optional). // - Each hunk body only has lines starting with ' ' | '+' | '-'. // - Each hunk includes at least one change (+ or -). | { op: "update", diff: string } // Diff is full file content, no prefixes. | { op: "create", diff: string } // No diff for delete. | { op: "delete" } // New path for update+move from the top-level path. | { op: "update", rename: string, diff: string } ``` Returns success/failure; on failure, error message indicates: - "Found multiple matches" — anchor/context not unique enough - "No match found" — context lines don't exist in file (wrong content or stale read) - Syntax errors in diff format - You MUST read the target file before editing - You MUST copy anchors and context lines verbatim (including whitespace) - You NEVER use anchors as comments (no line numbers, location labels, placeholders like `@@ @@`) - You NEVER place new lines outside the intended block - If edit fails or breaks structure, you MUST re-read the file and produce a new patch from current content — you NEVER retry the same diff - NEVER use edit to fix indentation, whitespace, or reformat code. Formatting is a single command run once at the end (`bun fmt`, `cargo fmt`, `prettier —write`, etc.)—not N individual edits. If you see inconsistent indentation after an edit, leave it; the formatter will fix all of it in one pass. # Create `edit {"path":"hello.txt","edits":[{"op":"create","diff":"Hello\n"}]}` # Update `edit {"path":"src/app.py","edits":[{"op":"update","diff":"@@ def greet():\n def greet():\n-print('Hi')\n+print('Hello')\n"}]}` # Rename `edit {"path":"src/app.py","edits":[{"op":"update","rename":"src/main.py","diff":"@@\n …\n"}]}` # Delete `edit {"path":"obsolete.txt","edits":[{"op":"delete"}]}` # Multiple entries All entries in one call apply to the top-level `path`; use separate calls for different files. - Generic anchors: `import`, `export`, `describe`, `function`, `const` - Repeating same addition in multiple hunks (duplicate blocks) - Full-file overwrites for minor changes (acceptable for major restructures or short files)