diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 194f5d2..c6cb43f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          fetch-depth: 0 # full history for astlog git refs
+          fetch-depth: 0 # full history for sigdiff git refs
 
       - uses: actions/setup-node@v4
         with:
diff --git a/CLAUDE.md b/CLAUDE.md
index 984bbe8..62c4ebc 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1,4 +1,4 @@
-# astlog
+# sigdiff
 
 Zero-config CLI that diffs the public API surface of a TypeScript project between two git refs and outputs a structured changelog.
 
@@ -20,7 +20,7 @@ src/
   diff.ts       — Two ApiSurfaces -> Change[]
   classify.ts   — Change -> SemverLevel
   format.ts     — ChangelogResult -> markdown or JSON
-  errors.ts     — Typed error union (AstlogError)
+  errors.ts     — Typed error union (SigdiffError)
   git.ts        — Read files at git refs, temp file management
   cli.ts        — Entry point, arg parsing, error boundary
   index.ts      — Barrel export for programmatic API
@@ -32,11 +32,11 @@ src/
 - **Discriminated unions over optional fields.** Each `Change` variant carries exactly its data.
 - **Validate at boundaries only.** CLI validates args. Internal functions trust typed inputs.
 - **Each function is independently useful.** `extract`, `diff`, `classify`, `format` are composable.
-- **Consistent error format.** Library code throws `AstlogException`, never calls `process.exit`.
+- **Consistent error format.** Library code throws `SigdiffException`, never calls `process.exit`.
 
 ## Conventions
 
-- Zero config — no `.astlogrc`, no config files
+- Zero config — no config files
 - `typescript` is a peer dep, `cac` for CLI parsing — that's it
 - `ExportedSymbol.signature` is a normalized string — comparison happens on strings, not AST nodes
 - `ApiSurface.symbols` keyed by `filePath:name` for cross-file uniqueness
diff --git a/README.md b/README.md
index f559d04..b04f33b 100644
--- a/README.md
+++ b/README.md
@@ -1,29 +1,29 @@
-# astlog
+# sigdiff
 
 Diffs the public API surface of a TypeScript project between two git refs and outputs a structured changelog.
 
 ```bash
-npx astlog v1.0.0..v2.0.0
+npx sigdiff v1.0.0..v2.0.0
 ```
 
 ## Why
 
-Commit messages are a human interpretation of a change — imprecise, incomplete, or missing entirely. `astlog` adds a second perspective: what the code actually exported. It catches things commit messages miss, like a signature change buried in a large PR.
+Commit messages are a human interpretation of a change — imprecise, incomplete, or missing entirely. `sigdiff` adds a second perspective: what the code actually exported. It catches things commit messages miss, like a signature change buried in a large PR.
 
 ## Usage
 
 ```bash
 # Compare last tag to HEAD
-npx astlog
+npx sigdiff
 
 # Compare two refs
-npx astlog v1.0.0..v2.0.0
+npx sigdiff v1.0.0..v2.0.0
 
 # Scope to a specific entrypoint
-npx astlog --entrypoint src/index.ts
+npx sigdiff --entrypoint src/index.ts
 
 # JSON output
-npx astlog --json
+npx sigdiff --json
 ```
 
 ## What it detects
@@ -51,7 +51,7 @@ Suggested version bump: major
 ## Programmatic API
 
 ```typescript
-import { extract, diff, classify, buildResult, format } from 'astlog';
+import { extract, diff, classify, buildResult, format } from 'sigdiff';
 
 const before = extract(['src/v1/index.ts']);
 const after = extract(['src/v2/index.ts']);
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 5c871a8..bd46ef3 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -19,7 +19,7 @@ src/
   classify.ts   — Change[] -> ClassifiedChange[] (semver levels)
   format.ts     — ChangelogResult -> markdown or JSON string
   types.ts      — All shared contracts
-  errors.ts     — Typed error union (AstlogError)
+  errors.ts     — Typed error union (SigdiffError)
   index.ts      — Barrel export for programmatic API
 ```
 
@@ -64,7 +64,7 @@ interface ChangelogResult {
 
 **Signature as string.** `ExportedSymbol.signature` is a canonical string, not raw AST nodes. Diff comparison is string equality. Signatures are normalized at extraction time (whitespace collapsed, semicolons standardized, index signatures canonicalized to `Record<>`).
 
-**Validate at boundaries only.** `cli.ts` validates args and catches `AstlogException`. Internal functions (`diff`, `classify`, `format`) trust typed inputs — no defensive checks.
+**Validate at boundaries only.** `cli.ts` validates args and catches `SigdiffException`. Internal functions (`diff`, `classify`, `format`) trust typed inputs — no defensive checks.
 
 **Arrow function detection.** `const fn = () => ...` is classified as `"function"` kind, not `"constant"`. The extractor checks if a variable declaration's type has call signatures.
 
@@ -79,7 +79,7 @@ interface ChangelogResult {
 ## Error Handling
 
 ```typescript
-type AstlogError =
+type SigdiffError =
   | { code: 'INVALID_REF'; message: string }
   | { code: 'NO_TAGS'; message: string }
   | { code: 'NO_TYPESCRIPT'; message: string }
@@ -87,7 +87,7 @@ type AstlogError =
   | { code: 'NOT_GIT_REPO'; message: string };
 ```
 
-Library code throws `AstlogException`. Only `cli.ts` calls `process.exit`.
+Library code throws `SigdiffException`. Only `cli.ts` calls `process.exit`.
 
 ## Semver Classification Rules
 
diff --git a/docs/PRODUCT.md b/docs/PRODUCT.md
index 040ab02..9f11378 100644
--- a/docs/PRODUCT.md
+++ b/docs/PRODUCT.md
@@ -1,4 +1,4 @@
-# astlog — Changelog from code, not commits
+# sigdiff — Changelog from code, not commits
 
 ## Problem
 
@@ -10,7 +10,7 @@ Every existing changelog tool (conventional-changelog, changesets, release-it, a
 
 ## Solution
 
-`astlog` reads what the code actually did. Your exported functions, types, and interfaces _are_ your API contract. If a function signature changed, that's a breaking change — regardless of what the commit message says.
+`sigdiff` reads what the code actually did. Your exported functions, types, and interfaces _are_ your API contract. If a function signature changed, that's a breaking change — regardless of what the commit message says.
 
 ```
 git ref A --> TS Compiler API --> API Surface A --\
@@ -22,16 +22,16 @@ git ref B --> TS Compiler API --> API Surface B --/
 
 ```bash
 # Compare last tag to HEAD
-npx astlog
+npx sigdiff
 
 # Compare two specific refs
-npx astlog v1.2.0..v1.3.0
+npx sigdiff v1.2.0..v1.3.0
 
 # Scope to barrel export only
-npx astlog --entrypoint src/index.ts
+npx sigdiff --entrypoint src/index.ts
 
 # Machine-readable output
-npx astlog --json
+npx sigdiff --json
 ```
 
 ## Example Output
@@ -52,7 +52,7 @@ npx astlog --json
 
 ### In
 
-- Single command: `astlog <ref>..<ref>` (defaults to last tag..HEAD)
+- Single command: `sigdiff <ref>..<ref>` (defaults to last tag..HEAD)
 - TypeScript files only (`.ts`, `.tsx`)
 - Detect exports: functions, interfaces, type aliases, enums, classes, constants
 - Diff: added / removed / signature-changed
@@ -60,7 +60,7 @@ npx astlog --json
 - Output: markdown (default) and `--json`
 - Zero config — works out of the box on any TS project
 - `--entrypoint` flag to scope to specific files
-- Programmatic API: `import { extract, diff, classify, format } from 'astlog'`
+- Programmatic API: `import { extract, diff, classify, format } from 'sigdiff'`
 
 ### Out of Scope
 
@@ -74,8 +74,8 @@ npx astlog --json
 
 ## Design Philosophy
 
-- Zero config. No `.astlogrc`, no `astlog.config.js`.
+- Zero config. No `.sigdiffrc`, no `sigdiff.config.js`.
 - Tiny dependency footprint. `typescript` as a peer dep and `cac` for CLI parsing.
 - One command, one output.
 - Composable — generates a changelog, doesn't manage releases. Pipe its output wherever you want.
-- Adopt in 30 seconds: `npx astlog` and you're done.
+- Adopt in 30 seconds: `npx sigdiff` and you're done.
diff --git a/docs/TODO.md b/docs/TODO.md
index f6247b4..f4dbb4a 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -1,4 +1,4 @@
-# astlog — TODO
+# sigdiff — TODO
 
 ## Next
 
diff --git a/package.json b/package.json
index 4c397e0..04b6418 100644
--- a/package.json
+++ b/package.json
@@ -1,11 +1,11 @@
 {
-  "name": "astlog",
+  "name": "sigdiff",
   "version": "0.1.0",
   "description": "Changelog from code, not commits. AST-based API surface diffing for TypeScript.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "bin": {
-    "astlog": "dist/cli.js"
+    "sigdiff": "dist/cli.js"
   },
   "files": [
     "dist"
@@ -33,7 +33,7 @@
   "license": "MIT",
   "repository": {
     "type": "git",
-    "url": "https://github.com/andydeng/astlog"
+    "url": "https://github.com/1dengaroo/sigdiff"
   },
   "engines": {
     "node": ">=18"
diff --git a/src/cli.ts b/src/cli.ts
index dca1c32..8340d44 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -1,13 +1,13 @@
 #!/usr/bin/env node
 
 import cac from 'cac';
-import { AstlogException } from './errors';
+import { SigdiffException } from './errors';
 import { assertGitRepo, extractAtRef, resolveRefs } from './git';
 import { diff } from './diff';
 import { classify } from './classify';
 import { buildResult, format } from './format';
 
-const cli = cac('astlog');
+const cli = cac('sigdiff');
 
 cli
   .command('[range]', 'Diff the public API surface between two git refs')
@@ -28,7 +28,7 @@ cli
 
       process.stdout.write(output);
     } catch (err) {
-      if (err instanceof AstlogException) {
+      if (err instanceof SigdiffException) {
         process.stderr.write(`Error: ${err.error.message}\n`);
         process.exit(1);
       }
diff --git a/src/errors.ts b/src/errors.ts
index 4f10b40..a3ef2ce 100644
--- a/src/errors.ts
+++ b/src/errors.ts
@@ -1,13 +1,13 @@
-export type AstlogError =
+export type SigdiffError =
   | { code: 'INVALID_REF'; message: string }
   | { code: 'NO_TAGS'; message: string }
   | { code: 'NO_TYPESCRIPT'; message: string }
   | { code: 'PARSE_ERROR'; message: string }
   | { code: 'NOT_GIT_REPO'; message: string };
 
-export class AstlogException extends Error {
-  constructor(public readonly error: AstlogError) {
+export class SigdiffException extends Error {
+  constructor(public readonly error: SigdiffError) {
     super(error.message);
-    this.name = 'AstlogException';
+    this.name = 'SigdiffException';
   }
 }
diff --git a/src/git.ts b/src/git.ts
index 65182d1..c0d5084 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -2,7 +2,7 @@ import { execSync } from 'child_process';
 import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
-import { AstlogException } from './errors';
+import { SigdiffException } from './errors';
 import { extract } from './extract';
 import { ApiSurface, ExportedSymbol } from './types';
 
@@ -10,9 +10,9 @@ export function assertGitRepo(): void {
   try {
     execSync('git rev-parse --git-dir', { stdio: 'ignore' });
   } catch {
-    throw new AstlogException({
+    throw new SigdiffException({
       code: 'NOT_GIT_REPO',
-      message: 'Not a git repository. Run astlog from inside a git repo.'
+      message: 'Not a git repository. Run sigdiff from inside a git repo.'
     });
   }
 }
@@ -24,7 +24,7 @@ export function resolveRefs(rangeArg?: string): {
   if (rangeArg) {
     const parts = rangeArg.split('..');
     if (parts.length !== 2 || !parts[0] || !parts[1]) {
-      throw new AstlogException({
+      throw new SigdiffException({
         code: 'INVALID_REF',
         message: `Invalid range format: "${rangeArg}". Expected format: <ref>..<ref>`
       });
@@ -40,9 +40,9 @@ export function resolveRefs(rangeArg?: string): {
       encoding: 'utf-8'
     }).trim();
   } catch {
-    throw new AstlogException({
+    throw new SigdiffException({
       code: 'NO_TAGS',
-      message: 'No git tags found. Provide an explicit range: astlog <ref>..<ref>'
+      message: 'No git tags found. Provide an explicit range: sigdiff <ref>..<ref>'
     });
   }
 
@@ -53,13 +53,13 @@ export function extractAtRef(ref: string, entrypoint?: string): ApiSurface {
   const files = discoverFiles(ref, entrypoint);
 
   if (files.length === 0) {
-    throw new AstlogException({
+    throw new SigdiffException({
       code: 'NO_TYPESCRIPT',
       message: `No TypeScript files found at ref "${ref}".`
     });
   }
 
-  const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'astlog-'));
+  const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'sigdiff-'));
 
   try {
     const pathMap = new Map<string, string>();
@@ -89,7 +89,7 @@ function validateRef(ref: string): void {
   try {
     execSync(`git rev-parse --verify ${ref}`, { stdio: 'ignore' });
   } catch {
-    throw new AstlogException({
+    throw new SigdiffException({
       code: 'INVALID_REF',
       message: `Git ref "${ref}" does not exist.`
     });
diff --git a/src/index.ts b/src/index.ts
index 947def3..68e9f6b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,7 +2,7 @@ export { extract } from './extract';
 export { diff } from './diff';
 export { classify } from './classify';
 export { buildResult, format } from './format';
-export { AstlogException } from './errors';
+export { SigdiffException } from './errors';
 
 export type {
   ApiSurface,
@@ -14,4 +14,4 @@ export type {
   SymbolKind
 } from './types';
 
-export type { AstlogError } from './errors';
+export type { SigdiffError } from './errors';