patch.py
python
| 1 | """muse patch — surgical semantic patch at symbol granularity. |
| 2 | |
| 3 | Modifies exactly one named symbol in a source file without touching any |
| 4 | surrounding code. The target is identified by its Muse symbol address |
| 5 | (``"file.py::SymbolName"`` or ``"file.py::ClassName.method"``). |
| 6 | |
| 7 | This command is the foundation for AI-agent-driven code modification. An |
| 8 | agent that needs to change ``src/billing.py::compute_invoice_total`` can |
| 9 | do so with surgical precision — no risk of accidentally modifying adjacent |
| 10 | functions, no diff noise, no merge headache. |
| 11 | |
| 12 | After patching, the working tree is dirty and ``muse status`` will show |
| 13 | exactly which symbol changed. Run ``muse commit`` as usual. |
| 14 | |
| 15 | Security note: the file path component of ADDRESS is validated via |
| 16 | ``contain_path()`` before any disk access. Paths that escape the repo root |
| 17 | (e.g. ``../../etc/passwd::foo``) are rejected with exit 1. |
| 18 | |
| 19 | Usage:: |
| 20 | |
| 21 | # Write new body to a file and apply it |
| 22 | muse patch "src/billing.py::compute_invoice_total" --body new_body.py |
| 23 | |
| 24 | # Read new body from stdin |
| 25 | echo "def foo(): return 42" | muse patch "src/utils.py::foo" --body - |
| 26 | |
| 27 | # Preview what will change without writing |
| 28 | muse patch "src/billing.py::compute_invoice_total" --body new_body.py --dry-run |
| 29 | |
| 30 | # Machine-readable output for agents |
| 31 | muse patch "src/utils.py::foo" --body new.py --json |
| 32 | |
| 33 | Output:: |
| 34 | |
| 35 | ✅ Patched src/billing.py::compute_invoice_total |
| 36 | Lines 2–4 replaced (was 3 lines, now 4 lines) |
| 37 | Surrounding code untouched (4 symbols preserved) |
| 38 | Run `muse status` to review, then `muse commit` |
| 39 | |
| 40 | JSON output (``--json``):: |
| 41 | |
| 42 | { |
| 43 | "address": "src/billing.py::compute_invoice_total", |
| 44 | "file": "src/billing.py", |
| 45 | "lines_replaced": 3, |
| 46 | "new_lines": 4, |
| 47 | "dry_run": false |
| 48 | } |
| 49 | """ |
| 50 | |
| 51 | from __future__ import annotations |
| 52 | |
| 53 | import json |
| 54 | import logging |
| 55 | import pathlib |
| 56 | import sys |
| 57 | |
| 58 | import typer |
| 59 | |
| 60 | from muse.core.errors import ExitCode |
| 61 | from muse.core.repo import require_repo |
| 62 | from muse.core.validation import contain_path |
| 63 | from muse.plugins.code.ast_parser import parse_symbols, validate_syntax |
| 64 | |
| 65 | logger = logging.getLogger(__name__) |
| 66 | |
| 67 | app = typer.Typer() |
| 68 | |
| 69 | |
| 70 | def _locate_symbol(file_path: pathlib.Path, address: str) -> tuple[int, int] | None: |
| 71 | """Return ``(lineno, end_lineno)`` for the symbol at *address* in *file_path*. |
| 72 | |
| 73 | Both values are 1-indexed. Returns ``None`` when the symbol is not found. |
| 74 | """ |
| 75 | try: |
| 76 | raw = file_path.read_bytes() |
| 77 | except OSError: |
| 78 | return None |
| 79 | rel = address.split("::")[0] |
| 80 | tree = parse_symbols(raw, rel) |
| 81 | rec = tree.get(address) |
| 82 | if rec is None: |
| 83 | return None |
| 84 | return rec["lineno"], rec["end_lineno"] |
| 85 | |
| 86 | |
| 87 | def _read_new_body(body_arg: str) -> str | None: |
| 88 | """Read the replacement source from *body_arg* (file path or ``"-"``).""" |
| 89 | if body_arg == "-": |
| 90 | return sys.stdin.read() |
| 91 | src = pathlib.Path(body_arg) |
| 92 | if not src.exists(): |
| 93 | return None |
| 94 | return src.read_text() |
| 95 | |
| 96 | |
| 97 | @app.callback(invoke_without_command=True) |
| 98 | def patch( |
| 99 | ctx: typer.Context, |
| 100 | address: str = typer.Argument( |
| 101 | ..., metavar="ADDRESS", |
| 102 | help='Symbol address, e.g. "src/billing.py::compute_invoice_total".', |
| 103 | ), |
| 104 | body_arg: str = typer.Option( |
| 105 | ..., "--body", "-b", metavar="FILE", |
| 106 | help='File containing the replacement source (use "-" for stdin).', |
| 107 | ), |
| 108 | dry_run: bool = typer.Option( |
| 109 | False, "--dry-run", "-n", |
| 110 | help="Print what would change without writing to disk.", |
| 111 | ), |
| 112 | as_json: bool = typer.Option(False, "--json", help="Emit result as JSON for agent consumption."), |
| 113 | ) -> None: |
| 114 | """Replace exactly one symbol's source — surgical precision for agents. |
| 115 | |
| 116 | ``muse patch`` locates the symbol at ADDRESS in the working tree, |
| 117 | reads the replacement source from --body, and splices it in at the |
| 118 | exact line range the symbol currently occupies. Every other symbol |
| 119 | in the file is untouched. |
| 120 | |
| 121 | The replacement source must define exactly the symbol being replaced |
| 122 | (same name, at the top level of the file passed via --body). Muse |
| 123 | verifies the patched file remains parseable before writing. |
| 124 | |
| 125 | The file path component of ADDRESS is validated against the repo root — |
| 126 | path-traversal addresses (e.g. ``../../etc/passwd::foo``) are rejected. |
| 127 | |
| 128 | After patching, run ``muse status`` to review the change, then |
| 129 | ``muse commit`` to record it. The structured delta will describe |
| 130 | exactly what changed at the semantic level (implementation changed, |
| 131 | signature changed, etc.). |
| 132 | """ |
| 133 | root = require_repo() |
| 134 | |
| 135 | # Parse address to get file path. |
| 136 | if "::" not in address: |
| 137 | typer.echo(f"❌ Invalid address '{address}' — must be 'file.py::SymbolName'.", err=True) |
| 138 | raise typer.Exit(code=ExitCode.USER_ERROR) |
| 139 | |
| 140 | rel_path, sym_name = address.split("::", 1) |
| 141 | |
| 142 | # Validate the file path stays inside the repo root. |
| 143 | try: |
| 144 | file_path = contain_path(root, rel_path) |
| 145 | except ValueError as exc: |
| 146 | typer.echo(f"❌ {exc}", err=True) |
| 147 | raise typer.Exit(code=ExitCode.USER_ERROR) |
| 148 | |
| 149 | if not file_path.exists(): |
| 150 | typer.echo(f"❌ File '{rel_path}' not found in working tree.", err=True) |
| 151 | raise typer.Exit(code=ExitCode.USER_ERROR) |
| 152 | |
| 153 | # Locate the symbol. |
| 154 | location = _locate_symbol(file_path, address) |
| 155 | if location is None: |
| 156 | typer.echo( |
| 157 | f"❌ Symbol '{address}' not found in {rel_path}.\n" |
| 158 | f" Run `muse symbols --file {rel_path}` to see available symbols.", |
| 159 | err=True, |
| 160 | ) |
| 161 | raise typer.Exit(code=ExitCode.USER_ERROR) |
| 162 | |
| 163 | start_line, end_line = location # 1-indexed, inclusive |
| 164 | |
| 165 | # Read the replacement source. |
| 166 | new_body = _read_new_body(body_arg) |
| 167 | if new_body is None: |
| 168 | typer.echo(f"❌ Could not read body from '{body_arg}'.", err=True) |
| 169 | raise typer.Exit(code=ExitCode.USER_ERROR) |
| 170 | |
| 171 | # Read current file. |
| 172 | original = file_path.read_text(encoding="utf-8") |
| 173 | lines = original.splitlines(keepends=True) |
| 174 | old_lines = lines[start_line - 1 : end_line] |
| 175 | |
| 176 | # Ensure new_body ends with a newline. |
| 177 | if not new_body.endswith("\n"): |
| 178 | new_body += "\n" |
| 179 | |
| 180 | # Splice. |
| 181 | new_lines = lines[: start_line - 1] + [new_body] + lines[end_line:] |
| 182 | new_content = "".join(new_lines) |
| 183 | |
| 184 | # Verify the patched file is still parseable for all supported languages. |
| 185 | syntax_error = validate_syntax(new_content.encode("utf-8"), rel_path) |
| 186 | if syntax_error is not None: |
| 187 | typer.echo(f"❌ Patched file has a {syntax_error}", err=True) |
| 188 | raise typer.Exit(code=ExitCode.USER_ERROR) |
| 189 | |
| 190 | new_line_count = new_body.count(chr(10)) |
| 191 | |
| 192 | if dry_run: |
| 193 | if as_json: |
| 194 | typer.echo(json.dumps({ |
| 195 | "address": address, |
| 196 | "file": rel_path, |
| 197 | "lines_replaced": len(old_lines), |
| 198 | "new_lines": new_line_count, |
| 199 | "dry_run": True, |
| 200 | }, indent=2)) |
| 201 | return |
| 202 | typer.echo(f"\n[dry-run] Would patch {rel_path}") |
| 203 | typer.echo(f" Symbol: {sym_name}") |
| 204 | typer.echo(f" Replace lines: {start_line}–{end_line} ({len(old_lines)} line(s))") |
| 205 | typer.echo(f" New source: {new_line_count} line(s)") |
| 206 | typer.echo(" No changes written (--dry-run).") |
| 207 | return |
| 208 | |
| 209 | file_path.write_text(new_content, encoding="utf-8") |
| 210 | |
| 211 | # Count remaining symbols for the "surrounding code untouched" message. |
| 212 | remaining = parse_symbols(file_path.read_bytes(), rel_path) |
| 213 | other_count = sum(1 for addr in remaining if addr != address) |
| 214 | |
| 215 | if as_json: |
| 216 | typer.echo(json.dumps({ |
| 217 | "address": address, |
| 218 | "file": rel_path, |
| 219 | "lines_replaced": len(old_lines), |
| 220 | "new_lines": new_line_count, |
| 221 | "dry_run": False, |
| 222 | }, indent=2)) |
| 223 | return |
| 224 | |
| 225 | typer.echo(f"\n✅ Patched {address}") |
| 226 | typer.echo(f" Lines {start_line}–{end_line} replaced ({len(old_lines)} → {new_line_count} line(s))") |
| 227 | typer.echo(f" Surrounding code untouched ({other_count} symbol(s) preserved)") |
| 228 | typer.echo(" Run `muse status` to review, then `muse commit`") |