f340ff941f
Initial import of the codespaces skill: query .belief_map.sexp for module boundaries, dependencies, blast radius, and the minimal files to read before non-trivial code changes. Includes the belief-map and infra-topology builders, the belief-search query engine and its tests, and reference docs for the S-expression notation and query patterns.
125 lines
3.6 KiB
Python
Executable File
125 lines
3.6 KiB
Python
Executable File
#!/usr/bin/env python3
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"""
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Git Descendants Finder -- find all commits that descend from HEAD.
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Builds a parent-child graph from git rev-list, then BFS-walks forward
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from HEAD to find all descendant commits. Useful for understanding
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what work was built on top of a given commit.
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Usage::
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git_descendants.py # descendants of HEAD
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git_descendants.py <ref> # descendants of a specific commit/ref
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"""
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from __future__ import annotations
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import subprocess
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import sys
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def run_git(cmd: str, cwd: str | None = None) -> list[str]:
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"""Run a git command and return output lines."""
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result = subprocess.run(cmd, shell=True, capture_output=True, text=True, cwd=cwd)
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if result.returncode != 0:
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print(f"Error running: {cmd}", file=sys.stderr)
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print(result.stderr, file=sys.stderr)
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sys.exit(1)
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return result.stdout.strip().split("\n") if result.stdout.strip() else []
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def get_commit_sha(ref: str = "HEAD", cwd: str | None = None) -> str:
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"""Resolve a ref to a full SHA."""
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result = subprocess.run(
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["git", "rev-parse", ref], capture_output=True, text=True, cwd=cwd,
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)
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if result.returncode != 0:
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print(f"Error: cannot resolve ref '{ref}'", file=sys.stderr)
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sys.exit(1)
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return result.stdout.strip()
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def build_parent_child_map(
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cwd: str | None = None,
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) -> tuple[dict[str, str], dict[str, list[str]]]:
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"""Build a map of commit -> leftmost parent and parent -> children."""
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print("Building commit graph...", file=sys.stderr)
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commits = run_git("git rev-list --all --reflog --parents", cwd=cwd)
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parent_map: dict[str, str] = {}
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children_map: dict[str, list[str]] = {}
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for line in commits:
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parts = line.split()
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if not parts:
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continue
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commit = parts[0]
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parents = parts[1:]
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if parents:
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leftmost_parent = parents[0]
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parent_map[commit] = leftmost_parent
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if leftmost_parent not in children_map:
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children_map[leftmost_parent] = []
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children_map[leftmost_parent].append(commit)
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print(f"Found {len(parent_map)} commits with parents", file=sys.stderr)
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return parent_map, children_map
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def find_all_descendants(
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commit: str, children_map: dict[str, list[str]],
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) -> set[str]:
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"""Find all descendants of a commit using BFS."""
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descendants: set[str] = set()
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queue = [commit]
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while queue:
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current = queue.pop(0)
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if current in children_map:
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for child in children_map[current]:
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if child not in descendants:
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descendants.add(child)
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queue.append(child)
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return descendants
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def main() -> None:
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ref = sys.argv[1] if len(sys.argv) > 1 else "HEAD"
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full_sha = get_commit_sha(ref)
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short_sha = subprocess.run(
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["git", "rev-parse", "--short", full_sha],
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capture_output=True, text=True,
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).stdout.strip()
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print(f"Finding descendants of {ref}: {short_sha}", file=sys.stderr)
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print(f"Full SHA: {full_sha}", file=sys.stderr)
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print(file=sys.stderr)
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_parent_map, children_map = build_parent_child_map()
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descendants = find_all_descendants(full_sha, children_map)
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print(f"Found {len(descendants)} descendant commits", file=sys.stderr)
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print(file=sys.stderr)
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if descendants:
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for commit in sorted(descendants):
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commit_info = subprocess.run(
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["git", "log", "-1", "--format=%h %s", commit],
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capture_output=True, text=True,
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).stdout.strip()
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print(commit_info)
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else:
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print("No descendants found", file=sys.stderr)
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if __name__ == "__main__":
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main()
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