Blast Radius Agent Skill

Blast Radius Analysis

Analyze the impact of current code changes using the

code knowledge graph.

When NOT To Use

• Reading the changed code for defects (use pensive:bug-review)
• The code graph is missing or stale (use gauntlet:graph-build)

Prerequisites

This skill requires the gauntlet plugin for graph

data. Check if it's available:

GRAPH_QUERY=$(find ~/.claude/plugins -name "graph_query.py" -path "*/gauntlet/*" 2>/dev/null | head -1)

If gauntlet is not installed (GRAPH_QUERY is empty):

Fall back to a manual impact analysis using git diff

and grep to trace imports and call sites. Skip graph

steps and go directly to step 3 (manual mode).

If gauntlet is installed but no graph.db exists:

Tell the user: "Run /gauntlet-graph build first."

Steps

• Show current changes: Run git diff --stat to

show the user what files changed.

• Run impact analysis (requires gauntlet):

   python3 "$GRAPH_QUERY" \
       --action impact --base-ref HEAD --depth 2

Fallback tier 1 (sem available, no gauntlet):

Use sem for cross-file dependency tracing:

   if command -v sem &>/dev/null; then
     sem impact --json <changed-file>
   fi

This traces real function-level dependencies instead

of filename matching. See leyline:sem-integration

for detection patterns.

Fallback tier 2 (no sem, no gauntlet): Trace

callers of changed functions with rg (or grep):

   # Prefer rg for speed; fall back to grep
   if command -v rg &>/dev/null; then
     git diff --name-only HEAD | while read f; do
       stem="${f%.*}"; stem="${stem##*/}"
       [ -z "$stem" ] && continue  # skip dotfiles (.gitignore etc.)
       rg -l "$stem" . 2>/dev/null
     done | sort -u
   else
     git diff --name-only HEAD | while read f; do
       stem="${f%.*}"; stem="${stem##*/}"
       [ -z "$stem" ] && continue  # skip dotfiles (.gitignore etc.)
       grep -rl "$stem" . 2>/dev/null
     done | sort -u
   fi

Note: this searches all file types. For Python-only

projects, add --type py to rg or --include="*.py"

to grep to reduce false positives.

• Display results in priority order:

Format the output as a table:

   Risk  | Node                    | File          | Anchor                          | Reason
   0.85  | auth.py::verify_token   | auth.py:45    | `def verify_token(token):`      | untested, security
   0.62  | db.py::execute_query    | db.py:112     | `cursor.execute(query, params)` | high fan-in
   0.41  | api.py::handle_request  | api.py:78     | `def handle_request(req):`      | flow participant

The Anchor column is the verbatim source text at the cited line.

It lets a reviewer confirm the finding without re-running the tool.

• Highlight untested functions: List any affected

functions that lack test coverage (no TESTED_BY edge).

• Show overall risk: Display the overall risk level

(low/medium/high) based on the maximum risk score.

• Suggest actions:
• For high-risk nodes: "Consider adding tests before

merging"

• For security-sensitive nodes: "Review authentication

and authorization logic carefully"

• For high-fan-in nodes: "Changes here affect many

callers; verify backward compatibility"

Verify Findings Are Grounded (blast-radius:findings-verified)

Every finding must cite a real location and a verbatim anchor. Write

findings to .review/findings.json and confirm each citation resolves:

python plugins/imbue/scripts/citation_verifier.py \
  --findings .review/findings.json --repo-root .

Drop or label UNVERIFIED any finding the verifier fails (exit 1); only

verified findings enter the report. See Skill(imbue:review-core) Step 5

and Skill(imbue:structured-output) for the schema.

Exit Criteria

• [ ] Results table lists every affected node with a File (file:line)

and verbatim Anchor column.

• [ ] Overall risk level (low/medium/high) is displayed based on the

maximum risk score.

• [ ] Every reported finding carries a Location + verbatim Anchor

confirmed by citation_verifier.py (exit 0), or unverified

findings were dropped or labeled UNVERIFIED.

Risk Scoring Model

Five weighted factors (sum capped at 1.0):

| Factor | Weight | Meaning |

|--------|--------|---------|

| Test gap | 0.30 | No test coverage |

| Security | 0.20 | Auth/crypto/SQL keywords |

| Flow participation | 0.25 | Part of execution flows |

| Cross-community | 0.15 | Called from other modules |

| Caller count | 0.10 | High fan-in function |