blastradius

Temporal code knowledge graph with blast-radius impact scoring, semantic symbol search, and git-history-aware dependency analysis — for AI-assisted development.

Point it at any project — Python, JavaScript/TypeScript, Go, Ruby, Rust, Java, PHP, and more — and get:

• A persistent SQLite graph store at <repo>/.blastradius/index.db — incremental, queryable, temporal
• A blastradius.json dependency index written directly into your repo (preserved for backward compatibility)
• Per-file blast-radius scores (how many files break if this one changes), including historical as-of queries
• A symbolindex.json symbol map so AI can find any function/class without scanning every file
• Hybrid semantic search over symbols: natural-language queries fused with keyword + graph expansion
• Git history backfill — temporal graph from commit history without touching the working tree
• Ten ways to consume the data: CLI, markdown report, MCP server (10 tools), pre-commit hook, CLAUDE.md injection
• An interactive visualization UI (2D/3D graphs, dependency matrix, treemap)

No build step. No npm. Zero required runtime dependencies — SQLite is stdlib.

Install

pip install blastradius

Or from source:

git clone https://github.com/scheidydude/blastradius
cd blastradius
pip install -e .

Quickstart

# Build the dependency index (also writes to .blastradius/index.db)
blastradius analyze ./myapp

# Build the symbol index (where every function and class lives)
blastradius symbols ./myapp

# See blast radius for a file before touching it
blastradius impact src/auth.py

# Search symbols with natural language (no embedding endpoint needed — FTS fallback)
blastradius search "validate auth token"

# See what changed since a release tag
blastradius changed-since v1.2.0

# Launch the visualization UI
blastradius serve --viz --repo ./myapp
open http://localhost:8080

Commands

blastradius analyze

blastradius analyze [REPO_PATH] [--output PATH] [--watch]

Analyzes the repo and writes blastradius.json to the repo root. Detects 12+ languages automatically.

blastradius symbols

blastradius symbols [REPO_PATH] [--output PATH] [--inline] [--index PATH]
                  [--claude-md] [--claude-md-path PATH] [--all-symbols]

Builds a symbol index — a map of every function, class, struct, and type to its exact file and line number. Lets AI tools (and humans) find any symbol in one lookup instead of scanning the entire repo.

Modes:

Both --inline and --claude-md can be combined in a single run.

Options:

Examples:

# Standalone symbol index
blastradius symbols ./myapp

# Embed into blastradius.json (one file for blast radius + symbols)
blastradius symbols ./myapp --inline

# Write CLAUDE.md summary so Claude Code loads symbols automatically
blastradius symbols ./myapp --claude-md

# All three at once
blastradius symbols ./myapp --inline --claude-md

# Re-generate when code changes
blastradius symbols ./myapp --inline --claude-md

Why it matters: Claude Code and other AI tools normally scan every file to find a function definition. With a symbol index, Claude can load one file, do an O(1) lookup, and open only the relevant file — cutting token usage 60–90% on symbol-location tasks.

CLAUDE.md injection is opt-in because it increases base context size on every prompt. Use it when symbol lookups are frequent in your workflow; skip it for simple tasks where the overhead outweighs the benefit.

blastradius impact

blastradius impact FILE [--index PATH] [--out FILE] [--json] [--as-of REF]

Shows the blast-radius impact for a specific file: direct dependents, transitive dependents, blast score, and risk level.

Impact: src/auth.py
Blast Score: 8.5  (2 direct · 7 transitive)  [HIGH]

Direct dependents (2)
  src/api.py
  src/middleware.py

Transitive dependents (5 additional)
  src/main.py  ← src/api.py
  src/app.py   ← src/middleware.py
  ...

Risk: HIGH — affects 7/42 files (16.7% of codebase)

Blast score formula: direct + (0.5 × transitive)

blastradius search

blastradius search QUERY [--k N] [--as-of REF] [--db PATH] [--json]

Hybrid semantic + keyword + graph symbol search. Finds relevant functions and classes without knowing their exact names.

Retrieval signals fused with Reciprocal Rank Fusion (RRF):

1. Semantic KNN — embedding similarity (requires blastradius[semantic] + a configured endpoint)
2. FTS5 keyword — full-text search over symbol names, signatures, and docstrings
3. Graph expansion — structurally adjacent symbols from dependent/dependency files

Degrades gracefully: if no embedding endpoint is configured, falls back to FTS + graph (no crash, no config needed).

# Keyword + graph search (no embedding setup required)
blastradius search "validate auth token"

# Full semantic search (requires BLASTRADIUS_EMBEDDING_* env vars)
BLASTRADIUS_EMBEDDING_ENDPOINT=http://localhost:11434 \
BLASTRADIUS_EMBEDDING_MODEL=nomic-embed-text \
BLASTRADIUS_EMBEDDING_DIMS=768 \
blastradius search "validate auth token"

# Historical search — symbols visible at a release tag
blastradius search "token validation" --as-of v1.2.0

blastradius history

blastradius history [REPO_PATH] [--since REF] [--max-commits N] [--json]

Backfills temporal graph data from git history — without any working-tree checkouts. Reads blobs via git cat-file --batch and stamps first_seen_commit / last_seen_commit on every file, edge, and symbol.

Run this once after initial setup to enable --as-of queries across the full history.

# Backfill up to 1000 commits (default)
blastradius history .

# Backfill only recent history
blastradius history . --since v1.0.0 --max-commits 200

blastradius changed-since

blastradius changed-since REF [--repo PATH] [--db PATH] [--json]

Lists files and dependency edges added or removed since a commit, branch, or tag.

$ blastradius changed-since v1.2.0
Changes since v1.2.0:

  Added files (2):
    + src/payments/stripe.py
    + src/payments/webhook.py

  Removed edges (1):
    - src/api.py → src/auth_v1.py  [imports]

blastradius db

blastradius db status [--db PATH] [--json]
blastradius db migrate [--db PATH]

Manages the SQLite store at <repo>/.blastradius/index.db.

$ blastradius db status
schema_version      : 2
repo_root           : /Users/alice/myapp
last_indexed_commit : a3f2e1c8
active_files        : 142
active_edges        : 387
active_symbols      : 1204
embedding_model     : nomic-embed-text
embedding_dims      : 768
vec_symbols         : enabled

db migrate applies any pending schema migrations automatically (also runs on every blastradius analyze).

blastradius serve

blastradius serve --viz [--repo PATH] [--port PORT] [--watch]
blastradius serve --mcp

--viz launches an interactive visualization UI in your browser (5 modes: 2D force graph, 3D network, dependency matrix, treemap, infrastructure graph).

--mcp starts a stdio MCP server that exposes blastradius tools directly to Claude and other MCP clients.

MCP tools:

Claude Code MCP config (.claude/settings.json):

{
  "mcpServers": {
    "blastradius": {
      "command": "blastradius",
      "args": ["serve", "--mcp"]
    }
  }
}

blastradius lookup

blastradius lookup SYMBOL [--index PATH] [--json]

Finds where a function, class, struct, or other symbol is defined. Queries the SQLite DB (same source as search), falling back to symbolindex.json if no DB is present. Prints 5 lines of source context around the definition.

$ blastradius lookup compute_blast_radius
blastradius/impact.py:6  compute_blast_radius  (function)

  >    6 | def compute_blast_radius(nodes: list[dict], links: list[dict]) -> dict[str, dict]:
         7 |     """..."""
         8 |     ...

$ blastradius lookup AuthService
src/auth.py:44  AuthService  (class)  methods: login, logout, refresh

  >   44 | class AuthService:
        45 |     def login(self, ...):

If a symbol isn't found, it's likely a third-party import — only symbols defined in the repo are indexed.

blastradius dependencies

blastradius dependencies FILE [--index PATH] [--json]

Shows what a file imports and what imports it, plus its blast score.

$ blastradius dependencies src/auth.py
File: src/auth.py  (blast score: 8.5)

Imports (3):
  src/db.py
  src/config.py
  src/utils.py

Imported by (2):
  src/api.py
  src/middleware.py

blastradius high-blast

blastradius high-blast [--threshold N] [--index PATH] [--json]

Lists all files whose blast score exceeds the threshold, sorted by score descending. Useful for identifying the riskiest files before a refactor.

$ blastradius high-blast --threshold 5
Files with blast score ≥ 5.0  (3 found)

  13.0  src/db.py          (12d / 2t)
   8.5  src/auth.py        (3d / 7t)
   5.5  src/config.py      (5d / 1t)

d = direct dependents · t = transitive dependents

blastradius symbol-blast

blastradius symbol-blast FILE [--json]

Per-export blast radius for a file. Lists every exported symbol with the count and exact file paths of importers that reference it by name. Useful when a file exports many symbols and you only need to touch one — lets you confirm the others are safe.

$ blastradius symbol-blast lib/db/schema.ts

Symbol-level blast radius: lib/db/schema.ts

  5 exported symbol(s), 12 importer(s)

  userSchema  (const, line 8)  →  8 user(s)
    app/api/users/route.ts
    app/api/profile/route.ts
    ...
  legacySchema  (const, line 42)  →  1 user(s)
    scripts/migrate.ts
  sessionSchema  (const, line 67)  →  3 user(s)
    ...

userSchema touches 8 routes; legacySchema touches only 1 — safe to change in isolation.

blastradius install-hook

blastradius install-hook [--repo PATH] [--threshold N] [--strict] [--remove]

Installs a git pre-commit hook that warns when staged files exceed the blast score threshold.

Using blastradius in another repo with Claude

Three workflows, ordered by automation level.

Workflow 1 — MCP server (recommended for active coding)

Claude gets symbol lookup, dependency, and impact tools it calls automatically. No extra prompting needed.

One-time setup:

cd /your/other/repo
blastradius analyze .
blastradius symbols .

Register the MCP server with Claude Code using claude mcp add. Use --scope project to limit it to this repo, or --scope global to use it everywhere:

# Project-scoped (recommended — stored in .claude/settings.json)
claude mcp add --scope project blastradius -- /path/to/blastradius serve --mcp

# Global (available in all repos)
claude mcp add --scope global blastradius -- /path/to/blastradius serve --mcp

Find the full path to your blastradius binary with which blastradius, then substitute it above.

# Example with conda install
claude mcp add --scope project blastradius -- /opt/homebrew/Caskroom/miniforge/base/bin/blastradius serve --mcp

Verify it registered:

claude mcp list

Note: Do not use "command": "blastradius" with a bare name — Claude Code does not inherit your shell PATH, so the binary won't be found unless you use the absolute path.

Claude now has all 10 MCP tools available in every session. When it needs to find processPayment, it calls lookup_symbol("processPayment") and gets src/billing.py:142 back in one shot — no file scanning. When it needs to find code that validates auth tokens without knowing the exact name, it calls semantic_search("validate auth token").

Keep the index fresh:

# Auto-rebuild on file changes (leave running in a terminal)
blastradius symbols . --watch

Workflow 2 — CLAUDE.md injection (best for repos you revisit often)

Symbol table is embedded in CLAUDE.md so it loads into every session automatically — no tool call needed at all.

cd /your/other/repo
blastradius symbols . --claude-md

This upserts a symbolindex code fence into CLAUDE.md. Every Claude Code session in that repo loads it at startup. Claude can answer "where is X defined?" from context alone with zero tool calls.

Tradeoff: adds ~500–2000 tokens to every prompt depending on repo size. Worth it for repos where symbol lookups are frequent; skip it for repos where you mostly write new code.

Keep it fresh:

# Re-run after significant refactors
blastradius analyze . && blastradius symbols . --claude-md

Workflow 3 — Hybrid (large repos)

For large repos where the --claude-md section would be too large, use the MCP server for lookups and add a short hint to CLAUDE.md so Claude reaches for the tool first:

blastradius analyze .
blastradius symbols .

Then add to CLAUDE.md:

## Blastradius
Symbol index: `symbolindex.json` — use the `lookup_symbol` MCP tool before grepping for any function or class.
Dependency index: `blastradius.json` — use `get_impact` before modifying high-blast files.

This costs almost no tokens but primes Claude to use the index rather than defaulting to grep.

CLI quick reference for human use

The same data available via MCP is also accessible directly from the terminal:

# Find where a symbol is defined (shows code snippet)
blastradius lookup MyClassName
blastradius lookup process_payment --json

# Show what a file imports and what depends on it
blastradius dependencies src/auth.py

# List the riskiest files to change
blastradius high-blast --threshold 5

# Blast-radius report before touching a file
blastradius impact src/auth.py

# Per-export blast radius — which importers use each exported symbol
blastradius symbol-blast lib/db/schema.ts

Which workflow to pick

Supported Languages

Output schemas

blastradius.json

{
  "meta": {
    "root": "myapp/",
    "total_files": 60,
    "total_loc": 4085,
    "languages": ["python", "javascript"]
  },
  "nodes": [
    {
      "id": "src/auth.py",
      "type": "module",
      "language": "python",
      "layer": "backend",
      "loc": 142,
      "imports": ["src/db.py"],
      "imported_by": ["src/api.py", "src/middleware.py"],
      "direct_dependents": 2,
      "transitive_dependents": 7,
      "blast_score": 5.5,
      "symbols": [
        { "name": "verify_token", "line": 18, "kind": "function", "exported": true },
        { "name": "AuthService",  "line": 44, "kind": "class",    "exported": true,
          "methods": ["login", "logout", "refresh"] }
      ]
    }
  ],
  "links": [
    { "source": "src/api.py", "target": "src/auth.py", "weight": 1, "kind": "imports" }
  ]
}

The symbols field is only present when blastradius symbols --inline has been run.

symbolindex.json

{
  "meta": {
    "generated": "2026-05-21",
    "repo": "myapp/",
    "total_symbols": 312
  },
  "symbols": {
    "verify_token": [
      {
        "file": "src/auth.py",
        "line": 18,
        "kind": "function",
        "exported": true,
        "doc": "Verify a JWT and return the decoded payload."
      }
    ],
    "AuthService": [
      {
        "file": "src/auth.py",
        "line": 44,
        "kind": "class",
        "exported": true,
        "methods": ["login", "logout", "refresh"]
      }
    ]
  },
  "file_symbols": {
    "src/auth.py": [
      { "name": "verify_token", "line": 18, "kind": "function", "exported": true },
      { "name": "AuthService",  "line": 44, "kind": "class",    "exported": true,
        "methods": ["login", "logout", "refresh"] }
    ]
  }
}

Lookup patterns:

• "Where is verify_token defined?" → symbols["verify_token"][0].file + .line — O(1)
• "What symbols live in src/auth.py?" → file_symbols["src/auth.py"] — O(1)
• "What's the blast radius of changing verify_token?" → cross-reference blastradius.json via the file

CLAUDE.md symbol section

When --claude-md is used, a compact section is upserted into CLAUDE.md bounded by HTML comment markers so re-runs update in place:

<!-- blastradius-symbols-start -->
## Symbol Index
_Generated by blastradius. Update: `blastradius symbols --claude-md`_

```symbolindex
src/auth.py: verify_token:fn:18 AuthService:cls:44[login,logout,refresh]
src/db.py: connect:fn:12 query:fn:28 close:fn:55

Format per symbol: `name:kind_abbr:line[methods...]`
Kind abbreviations: `fn` function · `cls` class · `st` struct · `en` enum · `tr` trait · `if` interface · `ty` type · `co` const

---

## AI workflow comparison

| Task | Without blastradius | With symbolindex.json |
|------|-------------------|----------------------|
| Find where `process_payment` is defined | Grep / scan ~200 files | Load 1 file, O(1) lookup |
| Understand blast radius of a change | Manual tracing | `blastradius impact <file>` |
| Load only relevant context | Full repo scan | File + line from symbol map |
| Estimated token savings | baseline | **60–90% on symbol tasks** |

---

## Optional dependencies

| Package | Purpose | Install |
|---------|---------|---------|
| `sqlite-vec` | Semantic vector search in `blastradius search` and `semantic_search` MCP tool | `pip install 'blastradius[semantic]'` |
| `watchdog` | `--watch` file change detection | `pip install 'blastradius[watch]'` |
| `PyYAML` | Better Docker Compose / CI YAML parsing | `pip install 'blastradius[yaml]'` |
| `tomli` | Rust `Cargo.toml` on Python < 3.11 | `pip install 'blastradius[toml]'` |

### Semantic search configuration

Semantic search requires a self-hosted embedding endpoint (Ollama, LM Studio, llama.cpp server, or any OpenAI-compatible `/v1/embeddings` API) and the `sqlite-vec` extension.

```bash
pip install 'blastradius[semantic]'

# Set env vars (add to your shell profile or .env)
export BLASTRADIUS_EMBEDDING_ENDPOINT=http://localhost:11434
export BLASTRADIUS_EMBEDDING_MODEL=nomic-embed-text
export BLASTRADIUS_EMBEDDING_DIMS=768

# Re-index to generate embeddings
blastradius analyze ./myapp

# Search
blastradius search "validate JWT token"

Without these env vars, blastradius search and the semantic_search MCP tool fall back to FTS5 keyword + graph search — no crash, no config required.

Requirements

• Python 3.9+
• A modern browser (for --viz mode)

License

Apache 2.0 — free to use and build on; attribution required in derivative works and documentation. Copyright 2026 David Scheiderman.