mcarvin8 · mcarvin8 · Apr 21, 2026 · Apr 20, 2026
diff --git a/README.md b/README.md
@@ -6,41 +6,84 @@
 [![Maintainability](https://qlty.sh/gh/mcarvin8/projects/smart-diff/maintainability.svg)](https://qlty.sh/gh/mcarvin8/projects/smart-diff)
 [![codecov](https://codecov.io/gh/mcarvin8/smart-diff/graph/badge.svg?token=H3ZWAGG7S9)](https://codecov.io/gh/mcarvin8/smart-diff)
 
-TypeScript library that turns a **git revision range** into a **Markdown summary** using an OpenAI-compatible Chat Completions API. It uses [`simple-git`](https://github.com/steveukx/git-js) to read the repo, respects **path includes/excludes** and **commit message include/exclude regexes**, and sends commits, paths, structured diff stats, and unified diff text to the model.
+TypeScript library that turns a **git revision range** into a **Markdown summary** using any LLM provider supported by the [Vercel AI SDK](https://sdk.vercel.ai) — OpenAI, Anthropic, Google Gemini, Amazon Bedrock, Mistral, Cohere, Groq, xAI, DeepSeek, or any OpenAI-compatible gateway. It uses [`simple-git`](https://github.com/steveukx/git-js) to read the repo, respects **path includes/excludes** and **commit message include/exclude regexes**, and sends commits, paths, structured diff stats, and unified diff text to the model.
 
 ## Requirements
 
 - **Node.js** 20+
-- OpenAI Configuration
-- [Git Bash](https://git-scm.com/install/)
+- An LLM provider credential (see [Provider configuration](#provider-configuration))
+- [Git](https://git-scm.com/) on the `PATH`
 
 ## Installation
 
 ```bash
 npm install @mcarvin/smart-diff
 ```
 
-## OpenAI Configuration
+`@ai-sdk/openai` and `@ai-sdk/openai-compatible` ship as direct dependencies. Every other provider (`@ai-sdk/anthropic`, `@ai-sdk/google`, `@ai-sdk/amazon-bedrock`, `@ai-sdk/mistral`, `@ai-sdk/cohere`, `@ai-sdk/groq`, `@ai-sdk/xai`, `@ai-sdk/deepseek`) is declared as an **optional peer** and only needs to be installed when you actually use that provider. If the package is missing, smart-diff throws a clear error telling you which one to install.
 
-The library is considered “configured” when `shouldUseLlmGateway()` is true: API key, base URL, and/or JSON default headers are set. Otherwise `summarizeGitDiff` / `generateSummary` throw with `LLM_GATEWAY_REQUIRED_MESSAGE` unless you pass **`openAiClientProvider`**.
+## Provider configuration
+
+smart-diff is "configured" when [`isLlmProviderConfigured()`](#lower-level-api) returns true — i.e. at least one supported provider can be resolved from env vars — **or** you pass your own `llmModelProvider` factory. Otherwise `summarizeGitDiff` / `generateSummary` throw with `LLM_GATEWAY_REQUIRED_MESSAGE`.
+
+### Selecting a provider
+
+`LLM_PROVIDER` explicitly selects a provider. When unset, the resolver auto-detects in this order: `LLM_BASE_URL`/`OPENAI_BASE_URL` → `openai-compatible`, `OPENAI_API_KEY`/`LLM_API_KEY` → `openai`, then `ANTHROPIC_API_KEY`, `GOOGLE_GENERATIVE_AI_API_KEY` (or `GOOGLE_API_KEY`), `MISTRAL_API_KEY`, `COHERE_API_KEY`, `GROQ_API_KEY`, `XAI_API_KEY`, `DEEPSEEK_API_KEY`, and finally `OPENAI_DEFAULT_HEADERS`/`LLM_DEFAULT_HEADERS` → `openai`.
+
+| Provider (`LLM_PROVIDER`) | Package | Credential env vars | Default model |
+|---|---|---|---|
+| `openai` | `@ai-sdk/openai` | `OPENAI_API_KEY` or `LLM_API_KEY` | `gpt-4o-mini` |
+| `openai-compatible` | `@ai-sdk/openai-compatible` | `LLM_BASE_URL` or `OPENAI_BASE_URL` (required); `OPENAI_API_KEY`/`LLM_API_KEY` or custom headers | `gpt-4o-mini` |
+| `anthropic` | `@ai-sdk/anthropic` | `ANTHROPIC_API_KEY` | `claude-3-5-haiku-latest` |
+| `google` | `@ai-sdk/google` | `GOOGLE_GENERATIVE_AI_API_KEY` or `GOOGLE_API_KEY` | `gemini-2.0-flash` |
+| `bedrock` | `@ai-sdk/amazon-bedrock` | Standard AWS credential chain (env / profile / role) | `anthropic.claude-3-5-haiku-20241022-v1:0` |
+| `mistral` | `@ai-sdk/mistral` | `MISTRAL_API_KEY` | `mistral-small-latest` |
+| `cohere` | `@ai-sdk/cohere` | `COHERE_API_KEY` | `command-r-08-2024` |
+| `groq` | `@ai-sdk/groq` | `GROQ_API_KEY` | `llama-3.1-8b-instant` |
+| `xai` | `@ai-sdk/xai` | `XAI_API_KEY` | `grok-2-latest` |
+| `deepseek` | `@ai-sdk/deepseek` | `DEEPSEEK_API_KEY` | `deepseek-chat` |
 
 > `LLM_*` wins over `OPENAI_*` where both exist.
 
+### Common env vars
+
 | Variable | Purpose |
-|----------|---------|
-| `OPENAI_API_KEY` or `LLM_API_KEY` | API key. Required by OpenAI client but can be null if gateway is set. |
-| `OPENAI_BASE_URL` or `LLM_BASE_URL` | Base URL for an OpenAI-compatible gateway. |
-| `OPENAI_DEFAULT_HEADERS` or `LLM_DEFAULT_HEADERS` | JSON object of extra headers; Can supply `Authorization` (e.g. raw `sk-…`) when no API key is set. |
-| `OPENAI_MAX_DIFF_CHARS` or `LLM_MAX_DIFF_CHARS`   | Max size of unified diff text sent to the model (default ~120k characters). |
-| `OPENAI_MAX_TOKENS` or `LLM_MAX_TOKENS` | Max completion tokens (default 4000). |
+|---|---|
+| `LLM_PROVIDER` | Explicit provider id from the table above. |
+| `LLM_MODEL` | Overrides the per-provider default model id. |
+| `OPENAI_BASE_URL` / `LLM_BASE_URL` | Base URL for an OpenAI-compatible gateway; presence alone auto-selects the `openai-compatible` provider. |
+| `OPENAI_DEFAULT_HEADERS` / `LLM_DEFAULT_HEADERS` | JSON object of extra headers merged onto OpenAI / OpenAI-compatible requests (e.g. RBAC tokens, raw `Authorization`). `LLM_*` overrides `OPENAI_*` key-by-key. |
+| `LLM_PROVIDER_NAME` | Display name used when `openai-compatible` is active (defaults to `openai-compatible`). |
+| `OPENAI_MAX_DIFF_CHARS` / `LLM_MAX_DIFF_CHARS` | Max size of unified diff text sent to the model (default ~120k characters). |
+| `OPENAI_MAX_TOKENS` / `LLM_MAX_TOKENS` | Max completion tokens (default 4000). |
+
+### Example: native OpenAI
 
-The client is created with the official [`openai`](https://www.npmjs.com/package/openai) SDK via `createOpenAiLikeClient()`; use a compatible endpoint and model ID for your provider.
+```powershell
+$env:OPENAI_API_KEY = "sk-..."
+# Optional: $env:LLM_MODEL = "gpt-4o"
+```
 
-Example using a company-managed OpenAI-compatible gateway:
+### Example: Anthropic Claude
+
+```powershell
+$env:ANTHROPIC_API_KEY = "sk-ant-..."
+$env:LLM_MODEL = "claude-3-5-sonnet-latest"   # optional override
+```
+
+### Example: company-managed OpenAI-compatible gateway
 
 ```powershell
-$env:OPENAI_DEFAULT_HEADERS = '{"x-company-rbac":"your-rbac-token-here","Authorization":"sk-your-api-key-here"}'
 $env:OPENAI_BASE_URL = "https://llm-gateway.example.com"
+$env:OPENAI_DEFAULT_HEADERS = '{"x-company-rbac":"your-rbac-token-here","Authorization":"Bearer sk-your-api-key-here"}'
+# LLM_PROVIDER is auto-detected as "openai-compatible" because LLM_BASE_URL/OPENAI_BASE_URL is set.
+```
+
+### Example: Google Gemini
+
+```powershell
+$env:GOOGLE_GENERATIVE_AI_API_KEY = "..."
+$env:LLM_MODEL = "gemini-2.0-flash"
 ```
 
 ## Usage
@@ -59,9 +102,10 @@ const markdown = await summarizeGitDiff({
   commitMessageExcludeRegexes: ['^\\[bot\\]'],
   commitMessageIncludeRegexes: ['^feat:'], // optional; OR across patterns
   teamName: 'Platform',
-  systemPrompt: undefined, // optional; overrides DEFAULT_GIT_DIFF_SYSTEM_PROMPT
-  model: 'gpt-4o-mini', // optional
-  maxDiffChars: 120_000, // optional; also see LLM_MAX_DIFF_CHARS
+  systemPrompt: undefined,   // optional; overrides DEFAULT_GIT_DIFF_SYSTEM_PROMPT
+  provider: 'anthropic',     // optional; overrides LLM_PROVIDER env + auto-detection
+  model: 'claude-3-5-sonnet-latest', // optional
+  maxDiffChars: 120_000,     // optional; also see LLM_MAX_DIFF_CHARS
 });
 ```
 
@@ -75,9 +119,27 @@ const markdown = await summarizeGitDiff({
 | `commitMessageExcludeRegexes` | Drop commits whose message matches **any** of these patterns. |
 | `teamName` | Adds a `Team:` line to the user payload for the model. |
 | `systemPrompt` | Replaces the default system prompt. |
-| `model` | Chat model id (default `gpt-4o-mini`). |
+| `provider` | `LlmProviderId` — wins over `LLM_PROVIDER` env and auto-detection. |
+| `model` | Chat model id; overrides `LLM_MODEL` and the provider default. |
 | `maxDiffChars` | Caps unified diff size for the request. |
-| `openAiClientProvider` | `() => Promise<OpenAiLikeClient>` — bypasses env-based client creation (required in tests or when you wire the SDK yourself). |
+| `llmModelProvider` | `() => Promise<LanguageModel>` — bypass env-based resolution entirely; hand-wire a Vercel AI SDK `LanguageModel` (required in tests or custom setups). |
+
+### Injecting your own `LanguageModel`
+
+If you want full control — for example, to configure retries, middlewares, or hit an in-process mock — pass `llmModelProvider`:
+
+```ts
+import { summarizeGitDiff } from '@mcarvin/smart-diff';
+import { createAnthropic } from '@ai-sdk/anthropic';
+
+const md = await summarizeGitDiff({
+  from: 'origin/main',
+  llmModelProvider: async () =>
+    createAnthropic({ apiKey: process.env.MY_ANTHROPIC_KEY })(
+      'claude-3-5-sonnet-latest',
+    ),
+});
+```
 
 ### Diff shape: single range vs per-commit
 
@@ -86,13 +148,28 @@ const markdown = await summarizeGitDiff({
 
 ### Lower-level API
 
-The package also exports helpers such as `createGitClient`, `getCommits`, `getDiff`, `getDiffSummary`, `getChangedFiles`, `filterCommitsByMessageRegexes`, `buildDiffPathspecs`, `generateSummary`, and OpenAI config utilities (`resolveLlmBaseUrl`, `shouldUseLlmGateway`, `createOpenAiLikeClient`, …). Use these if you build a custom pipeline but still want the same git and LLM behavior.
+The package also exports helpers for building a custom pipeline on top of the same git and LLM behavior:
+
+- **Git**: `createGitClient`, `getRepoRoot`, `getCommits`, `getDiff`, `getDiffSummary`, `getChangedFiles`, `filterCommitsByMessageRegexes`, `buildDiffPathspecs`
+- **AI**: `generateSummary`, `resolveLlmMaxDiffChars`, `truncateUnifiedDiffForLlm`
+- **Provider resolution**: `resolveLanguageModel`, `detectLlmProvider`, `isLlmProviderConfigured`, `defaultModelForProvider`, `resolveLlmBaseUrl`, `parseLlmDefaultHeadersFromEnv`
+- **Constants / types**: `DEFAULT_GIT_DIFF_SYSTEM_PROMPT`, `LLM_GATEWAY_REQUIRED_MESSAGE`, `LlmProviderId`, `LlmModelProvider`, `ResolveLanguageModelOptions`, `GenerateSummaryInput`, `SummarizeFlags`
+
+## Migrating from 1.x → 2.x
+
+v2 replaces the direct `openai` SDK dependency with the Vercel AI SDK. If you only rely on env-var configuration, your setup keeps working — `OPENAI_API_KEY`, `OPENAI_BASE_URL`, `OPENAI_DEFAULT_HEADERS`, `LLM_*` equivalents, `OPENAI_MAX_DIFF_CHARS`, and `OPENAI_MAX_TOKENS` are all still honored.
+
+Breaking changes:
+
+- **Removed `openAiClientProvider` option** on `summarizeGitDiff`/`generateSummary`. Use `llmModelProvider: () => Promise<LanguageModel>` returning a Vercel AI SDK model instead.
+- **Removed `OpenAiLikeClient` and `createOpenAiLikeClient` exports**, along with `shouldUseLlmGateway`. Use `isLlmProviderConfigured()` / `resolveLanguageModel()` instead.
+- **`openai` npm package is no longer a dependency.** Remove it from your own `package.json` if you only depended on it transitively via smart-diff.
 
 ## Used By
 
 This package is used by:
 
-- [sf-git-ai-meta-insights](https://github.com/mcarvin8/sf-git-ai-meta-insights) = Salesforce metadata wrapper compatible with Salesforce DX projects
+- [sf-git-ai-meta-insights](https://github.com/mcarvin8/sf-git-ai-meta-insights) — Salesforce metadata wrapper compatible with Salesforce DX projects
 
 ## License