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config-atlas/tools/blast_radius.py
tegwick 4620244f39
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feat(explain): complete ATLAS-WP-0004 — graph edges, blast-radius, determinism tests
T05: tests/test_effective_config.py (6 tests) — order-independence, most-specific
winner, no value/secret leak; wired into make validate + CI.
T04: tools/blast_radius.py + make blast-radius — consumers, transitive dependents
(cycle-safe), secret refs, fan-out risk band.
T03: tools/config_graph.py + make graph/graph-query — emit config-typed edges to
registry/indexes/graph.yaml (queryable by surface id); staleness check in the gate.

WP-0004 finished (5/5). Read-first control-plane MVP complete: explain, graph,
and blast-radius over the seeded surfaces.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-27 00:16:58 +02:00

122 lines
4.2 KiB
Python

#!/usr/bin/env python3
"""Blast-radius / dependency view (ATLAS-WP-0004-T04).
For a given configuration surface, traverse the relationship graph to list what a
change would affect: direct consumers (services), dependent surfaces (those that
reference or override it, transitively), referenced secrets, and the owner. This
supports change-risk reasoning before a change -- the
`config key -> service -> tenant -> feature -> secret -> owner` chain (research §5).
Reads only the registry (no live values). Reuses the surface loader from
effective_config.
Usage:
python3 tools/blast_radius.py surface.infotech.state-hub.api-config
make blast-radius SURFACE=surface.infotech.state-hub.api-config
"""
from __future__ import annotations
import sys
from collections import deque
from effective_config import SURFACES_DIR, load_entry
def load_all() -> dict[str, dict]:
return {p.stem: load_entry(p) for p in sorted(SURFACES_DIR.glob("*.md"))}
def relations(entry: dict) -> dict:
return entry.get("relations", {}) or {}
def build_reverse(entries: dict[str, dict]) -> dict[str, set[str]]:
"""id -> set of surface ids that reference it via related_to or overrides."""
rev: dict[str, set[str]] = {sid: set() for sid in entries}
for sid, e in entries.items():
rel = relations(e)
for target in list(rel.get("related_to", [])) + list(rel.get("overrides", [])):
rev.setdefault(target, set()).add(sid)
return rev
def dependent_closure(start: str, rev: dict[str, set[str]]) -> list[str]:
"""All surfaces that depend on `start` (transitively), nearest first.
The start node is excluded from its own closure even when relationship cycles
(e.g. mutual related_to edges) would otherwise loop back to it.
"""
seen: set[str] = {start}
order: list[str] = []
q = deque(sorted(rev.get(start, set())))
while q:
cur = q.popleft()
if cur in seen:
continue
seen.add(cur)
order.append(cur)
for nxt in sorted(rev.get(cur, set())):
if nxt not in seen:
q.append(nxt)
return order
def risk_band(score: int) -> str:
return "high" if score >= 4 else "medium" if score >= 2 else "low"
def render(surface_id: str, entries: dict[str, dict]) -> str:
if surface_id not in entries:
raise KeyError(surface_id)
e = entries[surface_id]
rel = relations(e)
rev = build_reverse(entries)
consumers = list(rel.get("consumed_by", []))
secrets = list(rel.get("depends_on_secret", []))
forward_related = list(rel.get("related_to", []))
dependents = dependent_closure(surface_id, rev)
score = len(consumers) + len(dependents)
lines: list[str] = []
lines.append(f"blast radius {surface_id}")
lines.append("")
lines.append(f" {e.get('name', surface_id)}")
lines.append(f" kind: {e.get('kind','?')} owner: {e.get('owner','?')} mutability: {e.get('mutability','?')}")
lines.append(f" risk: {risk_band(score)} (fan-out {score}: {len(consumers)} consumer(s) + {len(dependents)} dependent surface(s))")
lines.append("")
lines.append(" direct consumers (services):")
for c in consumers or ["(none)"]:
lines.append(f" - {c}")
lines.append(" dependent surfaces (reference/override this, transitively):")
for d in dependents or ["(none)"]:
owner = entries.get(d, {}).get("owner", "?")
lines.append(f" - {d} [owner: {owner}]")
lines.append(" referenced secrets (by reference only):")
for s in secrets or ["(none)"]:
lines.append(f" - {s}")
if forward_related:
lines.append(" related to:")
for r in forward_related:
lines.append(f" - {r}")
lines.append("")
lines.append(" · derived from registry relations only; no live values read")
return "\n".join(lines)
def main(argv: list[str]) -> int:
if len(argv) != 1:
print(__doc__)
return 2
entries = load_all()
try:
print(render(argv[0], entries))
except KeyError as exc:
print(f"error: no surface entry for id {exc}", file=sys.stderr)
return 1
return 0
if __name__ == "__main__":
raise SystemExit(main(sys.argv[1:]))