feat: Support OAuth authentication flows for Claude

Cargo.lock

@@ -2869,6 +2869,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "is-docker"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "928bae27f42bc99b60d9ac7334e3a21d10ad8f1835a4e12ec3ec0464765ed1b3"
+dependencies = [
+ "once_cell",
+]
+
 [[package]]
 name = "is-macro"
 version = "0.3.7"
@@ -2892,6 +2901,16 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "is-wsl"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "173609498df190136aa7dea1a91db051746d339e18476eed5ca40521f02d7aa5"
+dependencies = [
+ "is-docker",
+ "once_cell",
+]
+
 [[package]]
 name = "is_executable"
 version = "1.0.5"
@@ -3193,6 +3212,7 @@ dependencies = [
  "log4rs",
  "nu-ansi-term",
  "num_cpus",
+ "open",
  "os_info",
  "parking_lot",
  "path-absolutize",
@@ -3869,6 +3889,17 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
 
+[[package]]
+name = "open"
+version = "5.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43bb73a7fa3799b198970490a51174027ba0d4ec504b03cd08caf513d40024bc"
+dependencies = [
+ "is-wsl",
+ "libc",
+ "pathdiff",
+]
+
 [[package]]
 name = "openssl"
 version = "0.10.75"
@@ -4039,6 +4070,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "pathdiff"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df94ce210e5bc13cb6651479fa48d14f601d9858cfe0467f43ae157023b938d3"
+
 [[package]]
 name = "pem"
 version = "3.0.6"

Cargo.toml

@@ -96,6 +96,8 @@ colored = "3.0.0"
 clap_complete = { version = "4.5.58", features = ["unstable-dynamic"] }
 gman = "0.3.0"
 clap_complete_nushell = "4.5.9"
+open = "5"
+rand = "0.9.0"
 
 [dependencies.reqwest]
 version = "0.12.0"
@@ -126,7 +128,6 @@ arboard = { version = "3.3.0", default-features = false }
 
 [dev-dependencies]
 pretty_assertions = "1.4.0"
-rand = "0.9.0"
 
 [[bin]]
 name = "loki"

README.md

@@ -39,6 +39,7 @@ Coming from [AIChat](https://github.com/sigoden/aichat)? Follow the [migration g
     * [Todo System](./docs/TODO-SYSTEM.md): Built-in task tracking for improved agent reliability with smaller models.
 * [Environment Variables](./docs/ENVIRONMENT-VARIABLES.md): Override and customize your Loki configuration at runtime with environment variables.
 * [Client Configurations](./docs/clients/CLIENTS.md): Configuration instructions for various LLM providers.
+    * [Authentication (API Key & OAuth)](./docs/clients/CLIENTS.md#authentication): Authenticate with API keys or OAuth for subscription-based access.
     * [Patching API Requests](./docs/clients/PATCHES.md): Learn how to patch API requests for advanced customization.
 * [Custom Themes](./docs/THEMES.md): Change the look and feel of Loki to your preferences with custom themes.
 * [History](#history): A history of how Loki came to be.
@@ -150,6 +151,25 @@ guide you through the process when you first attempt to access the vault. So, to
 loki --list-secrets
 ```
 
+### Authentication
+Each client in your configuration needs authentication (with a few exceptions; e.g. ollama). Most clients use an API key
+(set via `api_key` in the config or through the [vault](./docs/VAULT.md)). For providers that support OAuth (e.g. Claude Pro/Max 
+subscribers), you can authenticate with your existing subscription instead:
+
+```yaml
+# In your config.yaml
+clients:
+  - type: claude
+    name: my-claude-oauth
+    auth: oauth # Indicate you want to authenticate with OAuth instead of an API key
+```
+
+```sh
+loki --authenticate my-claude-oauth
+```
+
+For full details, see the [authentication documentation](./docs/clients/CLIENTS.md#authentication).
+
 ### Tab-Completions
 You can also enable tab completions to make using Loki easier. To do so, add the following to your shell profile:
 ```shell

config.example.yaml

@@ -210,6 +210,7 @@ clients:
   - type: claude
     api_base: https://api.anthropic.com/v1              # Optional
     api_key: '{{ANTHROPIC_API_KEY}}'                    # You can either hard-code or inject secrets from the Loki vault
+    auth: null                                          # When set to 'oauth', Loki will use OAuth instead of an API key; Authenticate with `loki --authenticate`
 
   # See https://docs.mistral.ai/
   - type: openai-compatible

docs/clients/CLIENTS.md

@@ -14,6 +14,7 @@ loki --info | grep 'config_file' | awk '{print $2}'
 <!--toc:start-->
 - [Supported Clients](#supported-clients)
 - [Client Configuration](#client-configuration)
+- [Authentication](#authentication)
 - [Extra Settings](#extra-settings)
 <!--toc:end-->
 
@@ -51,12 +52,13 @@ clients:
 The client metadata uniquely identifies the client in Loki so you can reference it across your configurations. The 
 available settings are listed below:
 
-| Setting  | Description                                                                                   |
+| Setting  | Description                                                                                                |
-|----------|-----------------------------------------------------------------------------------------------|
+|----------|------------------------------------------------------------------------------------------------------------|
-| `name`   | The name of the client (e.g. `openai`, `gemini`, etc.)                                        |
+| `name`   | The name of the client (e.g. `openai`, `gemini`, etc.)                                                     |
-| `models` | See the [model settings](#model-settings) documentation below                                 |
+| `auth`   | Authentication method: `oauth` for OAuth, or omit to use `api_key` (see [Authentication](#authentication)) |
-| `patch`  | See the [client patch configuration](./PATCHES.md#client-configuration-patches) documentation |
+| `models` | See the [model settings](#model-settings) documentation below                                              |
-| `extra`  | See the [extra settings](#extra-settings) documentation below                                 |
+| `patch`  | See the [client patch configuration](./PATCHES.md#client-configuration-patches) documentation              |
+| `extra`  | See the [extra settings](#extra-settings) documentation below                                              |
 
 Be sure to also check provider-specific configurations for any extra fields that are added for authentication purposes.
 
@@ -83,6 +85,73 @@ The `models` array lists the available models from the model client. Each one ha
 | `default_chunk_size`        |          | `embedding` | The default chunk size to use with the given model                                                                                                                                                                                            |
 | `max_batch_size`            |          | `embedding` | The maximum batch size that the given embedding model supports                                                                                                                                                                                |
 
+## Authentication
+
+Loki clients support two authentication methods: **API keys** and **OAuth**. Each client entry in your configuration
+must use one or the other.
+
+### API Key Authentication
+
+Most clients authenticate using an API key. Simply set the `api_key` field directly or inject it from the
+[Loki vault](../VAULT.md):
+
+```yaml
+clients:
+  - type: claude
+    api_key: '{{ANTHROPIC_API_KEY}}'
+```
+
+API keys can also be provided via environment variables named `{CLIENT_NAME}_API_KEY` (e.g. `OPENAI_API_KEY`,
+`GEMINI_API_KEY`). See the [environment variables documentation](../ENVIRONMENT-VARIABLES.md#client-related-variables)
+for details.
+
+### OAuth Authentication
+
+For [providers that support OAuth](#providers-that-support-oauth), you can authenticate using your existing subscription instead of an API key. This uses
+the OAuth 2.0 PKCE flow.
+
+**Step 1: Configure the client**
+
+Add a client entry with `auth: oauth` and no `api_key`:
+
+```yaml
+clients:
+  - type: claude
+    name: my-claude-oauth
+    auth: oauth
+```
+
+**Step 2: Authenticate**
+
+Run the `--authenticate` flag with the client name:
+
+```sh
+loki --authenticate my-claude-oauth
+```
+
+This opens your browser for the OAuth authorization flow. After authorizing, paste the authorization code back into
+the terminal. Loki stores the tokens in `~/.cache/loki/oauth` and automatically refreshes them when they expire.
+
+If you have only one OAuth-configured client, you can omit the name:
+
+```sh
+loki --authenticate
+```
+
+**Step 3: Use normally**
+
+Once authenticated, the client works like any other. Loki uses the stored OAuth tokens automatically:
+
+```sh
+loki -m my-claude-oauth:claude-sonnet-4-20250514 "Hello!"
+```
+
+> **Note:** You can have multiple clients for the same provider. For example: you can have one with an API key and 
+> another with OAuth. Use the `name` field to distinguish them.
+
+### Providers That Support OAuth
+* Claude
+
 ## Extra Settings
 Loki also lets you customize some extra settings for interacting with APIs:
 

src/cli/mod.rs

@@ -127,6 +127,9 @@ pub struct Cli {
     /// List all secrets stored in the Loki vault
     #[arg(long, exclusive = true)]
     pub list_secrets: bool,
+    /// Authenticate with an LLM provider using OAuth (e.g., --authenticate client_name)
+    #[arg(long, exclusive = true, value_name = "CLIENT_NAME")]
+    pub authenticate: Option<Option<String>>,
     /// Generate static shell completion scripts
     #[arg(long, value_name = "SHELL", value_enum)]
     pub completions: Option<ShellCompletion>,

src/client/claude.rs

@@ -1,9 +1,12 @@
+use super::access_token::get_access_token;
+use super::claude_oauth::ClaudeOAuthProvider;
+use super::oauth::{self, OAuthProvider};
 use super::*;
 
 use crate::utils::strip_think_tag;
 
 use anyhow::{Context, Result, bail};
-use reqwest::RequestBuilder;
+use reqwest::{Client as ReqwestClient, RequestBuilder};
 use serde::Deserialize;
 use serde_json::{Value, json};
 
@@ -14,6 +17,7 @@ pub struct ClaudeConfig {
     pub name: Option<String>,
     pub api_key: Option<String>,
     pub api_base: Option<String>,
+    pub auth: Option<String>,
     #[serde(default)]
     pub models: Vec<ModelData>,
     pub patch: Option<RequestPatch>,
@@ -27,22 +31,37 @@ impl ClaudeClient {
     pub const PROMPTS: [PromptAction<'static>; 1] = [("api_key", "API Key", None, true)];
 }
 
-impl_client_trait!(
+#[async_trait::async_trait]
-    ClaudeClient,
+impl Client for ClaudeClient {
-    (
+    client_common_fns!();
-        prepare_chat_completions,
-        claude_chat_completions,
-        claude_chat_completions_streaming
-    ),
-    (noop_prepare_embeddings, noop_embeddings),
-    (noop_prepare_rerank, noop_rerank),
-);
 
-fn prepare_chat_completions(
+    async fn chat_completions_inner(
+        &self,
+        client: &ReqwestClient,
+        data: ChatCompletionsData,
+    ) -> Result<ChatCompletionsOutput> {
+        let request_data = prepare_chat_completions(self, client, data).await?;
+        let builder = self.request_builder(client, request_data);
+        claude_chat_completions(builder, self.model()).await
+    }
+
+    async fn chat_completions_streaming_inner(
+        &self,
+        client: &ReqwestClient,
+        handler: &mut SseHandler,
+        data: ChatCompletionsData,
+    ) -> Result<()> {
+        let request_data = prepare_chat_completions(self, client, data).await?;
+        let builder = self.request_builder(client, request_data);
+        claude_chat_completions_streaming(builder, handler, self.model()).await
+    }
+}
+
+async fn prepare_chat_completions(
     self_: &ClaudeClient,
+    client: &ReqwestClient,
     data: ChatCompletionsData,
 ) -> Result<RequestData> {
-    let api_key = self_.get_api_key()?;
     let api_base = self_
         .get_api_base()
         .unwrap_or_else(|_| API_BASE.to_string());
@@ -53,7 +72,33 @@ fn prepare_chat_completions(
     let mut request_data = RequestData::new(url, body);
 
     request_data.header("anthropic-version", "2023-06-01");
-    request_data.header("x-api-key", api_key);
+
+    let uses_oauth = self_.config.auth.as_deref() == Some("oauth");
+
+    if uses_oauth {
+        let provider = ClaudeOAuthProvider;
+        let ready = oauth::prepare_oauth_access_token(client, &provider, self_.name()).await?;
+        if !ready {
+            bail!(
+                "OAuth configured but no tokens found for '{}'. Run: loki --authenticate {}",
+                self_.name(),
+                self_.name()
+            );
+        }
+        let token = get_access_token(self_.name())?;
+        request_data.bearer_auth(token);
+        for (key, value) in provider.extra_request_headers() {
+            request_data.header(key, value);
+        }
+    } else if let Ok(api_key) = self_.get_api_key() {
+        request_data.header("x-api-key", api_key);
+    } else {
+        bail!(
+            "No authentication configured for '{}'. Set `api_key` or use `auth: oauth` with `loki --authenticate {}`.",
+            self_.name(),
+            self_.name()
+        );
+    }
 
     Ok(request_data)
 }

src/client/claude_oauth.rs

@@ -0,0 +1,39 @@
+use super::oauth::OAuthProvider;
+
+pub const BETA_HEADER: &str = "oauth-2025-04-20";
+
+pub struct ClaudeOAuthProvider;
+
+impl OAuthProvider for ClaudeOAuthProvider {
+    fn provider_name(&self) -> &str {
+        "claude"
+    }
+
+    fn client_id(&self) -> &str {
+        "9d1c250a-e61b-44d9-88ed-5944d1962f5e"
+    }
+
+    fn authorize_url(&self) -> &str {
+        "https://claude.ai/oauth/authorize"
+    }
+
+    fn token_url(&self) -> &str {
+        "https://console.anthropic.com/v1/oauth/token"
+    }
+
+    fn redirect_uri(&self) -> &str {
+        "https://console.anthropic.com/oauth/code/callback"
+    }
+
+    fn scopes(&self) -> &str {
+        "org:create_api_key user:profile user:inference"
+    }
+
+    fn extra_token_headers(&self) -> Vec<(&str, &str)> {
+        vec![("anthropic-beta", BETA_HEADER)]
+    }
+
+    fn extra_request_headers(&self) -> Vec<(&str, &str)> {
+        vec![("anthropic-beta", BETA_HEADER)]
+    }
+}

src/client/common.rs

@@ -489,14 +489,6 @@ pub async fn call_chat_completions_streaming(
     }
 }
 
-pub fn noop_prepare_embeddings<T>(_client: &T, _data: &EmbeddingsData) -> Result<RequestData> {
-    bail!("The client doesn't support embeddings api")
-}
-
-pub async fn noop_embeddings(_builder: RequestBuilder, _model: &Model) -> Result<EmbeddingsOutput> {
-    bail!("The client doesn't support embeddings api")
-}
-
 pub fn noop_prepare_rerank<T>(_client: &T, _data: &RerankData) -> Result<RequestData> {
     bail!("The client doesn't support rerank api")
 }

src/client/mod.rs

@@ -1,6 +1,8 @@
 mod access_token;
+mod claude_oauth;
 mod common;
 mod message;
+pub mod oauth;
 #[macro_use]
 mod macros;
 mod model;

src/client/oauth.rs

@@ -0,0 +1,279 @@
+use super::ClientConfig;
+use super::access_token::{is_valid_access_token, set_access_token};
+use crate::config::Config;
+use anyhow::{Result, bail};
+use base64::Engine;
+use base64::engine::general_purpose::URL_SAFE_NO_PAD;
+use chrono::Utc;
+use inquire::Text;
+use reqwest::Client as ReqwestClient;
+use serde::{Deserialize, Serialize};
+use serde_json::{Value, json};
+use sha2::{Digest, Sha256};
+use std::fs;
+use uuid::Uuid;
+
+pub trait OAuthProvider: Send + Sync {
+    fn provider_name(&self) -> &str;
+    fn client_id(&self) -> &str;
+    fn authorize_url(&self) -> &str;
+    fn token_url(&self) -> &str;
+    fn redirect_uri(&self) -> &str;
+    fn scopes(&self) -> &str;
+
+    fn extra_token_headers(&self) -> Vec<(&str, &str)> {
+        vec![]
+    }
+
+    fn extra_request_headers(&self) -> Vec<(&str, &str)> {
+        vec![]
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct OAuthTokens {
+    pub access_token: String,
+    pub refresh_token: String,
+    pub expires_at: i64,
+}
+
+pub async fn run_oauth_flow(provider: &impl OAuthProvider, client_name: &str) -> Result<()> {
+    let random_bytes: [u8; 32] = rand::random::<[u8; 32]>();
+    let code_verifier = URL_SAFE_NO_PAD.encode(random_bytes);
+
+    let mut hasher = Sha256::new();
+    hasher.update(code_verifier.as_bytes());
+    let code_challenge = URL_SAFE_NO_PAD.encode(hasher.finalize());
+
+    let state = Uuid::new_v4().to_string();
+
+    let encoded_scopes = urlencoding::encode(provider.scopes());
+    let encoded_redirect = urlencoding::encode(provider.redirect_uri());
+
+    let authorize_url = format!(
+        "{}?code=true&client_id={}&response_type=code&scope={}&redirect_uri={}&code_challenge={}&code_challenge_method=S256&state={}",
+        provider.authorize_url(),
+        provider.client_id(),
+        encoded_scopes,
+        encoded_redirect,
+        code_challenge,
+        state
+    );
+
+    println!(
+        "\nOpen this URL to authenticate with {} (client '{}'):\n",
+        provider.provider_name(),
+        client_name
+    );
+    println!("  {authorize_url}\n");
+
+    let _ = open::that(&authorize_url);
+
+    let input = Text::new("Paste the authorization code:").prompt()?;
+
+    let parts: Vec<&str> = input.splitn(2, '#').collect();
+    if parts.len() != 2 {
+        bail!("Invalid authorization code format. Expected format: <code>#<state>");
+    }
+    let code = parts[0];
+    let returned_state = parts[1];
+
+    if returned_state != state {
+        bail!(
+            "OAuth state mismatch: expected '{state}', got '{returned_state}'. \
+             This may indicate a CSRF attack or a stale authorization attempt."
+        );
+    }
+
+    let client = ReqwestClient::new();
+    let mut request = client.post(provider.token_url()).json(&json!({
+        "grant_type": "authorization_code",
+        "client_id": provider.client_id(),
+        "code": code,
+        "code_verifier": code_verifier,
+        "redirect_uri": provider.redirect_uri(),
+        "state": state,
+    }));
+
+    for (key, value) in provider.extra_token_headers() {
+        request = request.header(key, value);
+    }
+
+    let response: Value = request.send().await?.json().await?;
+
+    let access_token = response["access_token"]
+        .as_str()
+        .ok_or_else(|| anyhow::anyhow!("Missing access_token in response: {response}"))?
+        .to_string();
+    let refresh_token = response["refresh_token"]
+        .as_str()
+        .ok_or_else(|| anyhow::anyhow!("Missing refresh_token in response: {response}"))?
+        .to_string();
+    let expires_in = response["expires_in"]
+        .as_i64()
+        .ok_or_else(|| anyhow::anyhow!("Missing expires_in in response: {response}"))?;
+
+    let expires_at = Utc::now().timestamp() + expires_in;
+
+    let tokens = OAuthTokens {
+        access_token,
+        refresh_token,
+        expires_at,
+    };
+
+    save_oauth_tokens(client_name, &tokens)?;
+
+    println!(
+        "Successfully authenticated client '{}' with {} via OAuth. Tokens saved.",
+        client_name,
+        provider.provider_name()
+    );
+
+    Ok(())
+}
+
+pub fn load_oauth_tokens(client_name: &str) -> Option<OAuthTokens> {
+    let path = Config::token_file(client_name);
+    let content = fs::read_to_string(path).ok()?;
+    serde_json::from_str(&content).ok()
+}
+
+fn save_oauth_tokens(client_name: &str, tokens: &OAuthTokens) -> Result<()> {
+    let path = Config::token_file(client_name);
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent)?;
+    }
+    let json = serde_json::to_string_pretty(tokens)?;
+    fs::write(path, json)?;
+    Ok(())
+}
+
+pub async fn refresh_oauth_token(
+    client: &ReqwestClient,
+    provider: &dyn OAuthProvider,
+    client_name: &str,
+    tokens: &OAuthTokens,
+) -> Result<OAuthTokens> {
+    let mut request = client.post(provider.token_url()).json(&json!({
+        "grant_type": "refresh_token",
+        "client_id": provider.client_id(),
+        "refresh_token": tokens.refresh_token,
+    }));
+
+    for (key, value) in provider.extra_token_headers() {
+        request = request.header(key, value);
+    }
+
+    let response: Value = request.send().await?.json().await?;
+
+    let access_token = response["access_token"]
+        .as_str()
+        .ok_or_else(|| anyhow::anyhow!("Missing access_token in refresh response: {response}"))?
+        .to_string();
+    let refresh_token = response["refresh_token"]
+        .as_str()
+        .ok_or_else(|| anyhow::anyhow!("Missing refresh_token in refresh response: {response}"))?
+        .to_string();
+    let expires_in = response["expires_in"]
+        .as_i64()
+        .ok_or_else(|| anyhow::anyhow!("Missing expires_in in refresh response: {response}"))?;
+
+    let expires_at = Utc::now().timestamp() + expires_in;
+
+    let new_tokens = OAuthTokens {
+        access_token,
+        refresh_token,
+        expires_at,
+    };
+
+    save_oauth_tokens(client_name, &new_tokens)?;
+
+    Ok(new_tokens)
+}
+
+pub async fn prepare_oauth_access_token(
+    client: &ReqwestClient,
+    provider: &impl OAuthProvider,
+    client_name: &str,
+) -> Result<bool> {
+    if is_valid_access_token(client_name) {
+        return Ok(true);
+    }
+
+    let tokens = match load_oauth_tokens(client_name) {
+        Some(t) => t,
+        None => return Ok(false),
+    };
+
+    let tokens = if Utc::now().timestamp() >= tokens.expires_at {
+        refresh_oauth_token(client, provider, client_name, &tokens).await?
+    } else {
+        tokens
+    };
+
+    set_access_token(client_name, tokens.access_token.clone(), tokens.expires_at);
+
+    Ok(true)
+}
+
+pub fn get_oauth_provider(provider_type: &str) -> Option<impl OAuthProvider> {
+    match provider_type {
+        "claude" => Some(super::claude_oauth::ClaudeOAuthProvider),
+        _ => None,
+    }
+}
+
+pub fn resolve_provider_type(client_name: &str, clients: &[ClientConfig]) -> Option<&'static str> {
+    for client_config in clients {
+        let (config_name, provider_type, auth) = client_config_info(client_config);
+        if config_name == client_name {
+            if auth == Some("oauth") && get_oauth_provider(provider_type).is_some() {
+                return Some(provider_type);
+            }
+            return None;
+        }
+    }
+    None
+}
+
+pub fn list_oauth_capable_clients(clients: &[ClientConfig]) -> Vec<String> {
+    clients
+        .iter()
+        .filter_map(|client_config| {
+            let (name, provider_type, auth) = client_config_info(client_config);
+            if auth == Some("oauth") && get_oauth_provider(provider_type).is_some() {
+                Some(name.to_string())
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
+fn client_config_info(client_config: &ClientConfig) -> (&str, &'static str, Option<&str>) {
+    match client_config {
+        ClientConfig::ClaudeConfig(c) => (
+            c.name.as_deref().unwrap_or("claude"),
+            "claude",
+            c.auth.as_deref(),
+        ),
+        ClientConfig::OpenAIConfig(c) => (c.name.as_deref().unwrap_or("openai"), "openai", None),
+        ClientConfig::OpenAICompatibleConfig(c) => (
+            c.name.as_deref().unwrap_or("openai-compatible"),
+            "openai-compatible",
+            None,
+        ),
+        ClientConfig::GeminiConfig(c) => (c.name.as_deref().unwrap_or("gemini"), "gemini", None),
+        ClientConfig::CohereConfig(c) => (c.name.as_deref().unwrap_or("cohere"), "cohere", None),
+        ClientConfig::AzureOpenAIConfig(c) => (
+            c.name.as_deref().unwrap_or("azure-openai"),
+            "azure-openai",
+            None,
+        ),
+        ClientConfig::VertexAIConfig(c) => {
+            (c.name.as_deref().unwrap_or("vertexai"), "vertexai", None)
+        }
+        ClientConfig::BedrockConfig(c) => (c.name.as_deref().unwrap_or("bedrock"), "bedrock", None),
+        ClientConfig::Unknown => ("unknown", "unknown", None),
+    }
+}

src/config/mod.rs

@@ -428,6 +428,14 @@ impl Config {
         base_dir.join(env!("CARGO_CRATE_NAME"))
     }
 
+    pub fn oauth_tokens_path() -> PathBuf {
+        Self::cache_path().join("oauth")
+    }
+
+    pub fn token_file(client_name: &str) -> PathBuf {
+        Self::oauth_tokens_path().join(format!("{client_name}_oauth_tokens.json"))
+    }
+
     pub fn log_path() -> PathBuf {
         Config::cache_path().join(format!("{}.log", env!("CARGO_CRATE_NAME")))
     }

src/main.rs

@@ -16,7 +16,7 @@ mod vault;
 extern crate log;
 
 use crate::client::{
-    ModelType, call_chat_completions, call_chat_completions_streaming, list_models,
+    ModelType, call_chat_completions, call_chat_completions_streaming, list_models, oauth,
 };
 use crate::config::{
     Agent, CODE_ROLE, Config, EXPLAIN_SHELL_ROLE, GlobalConfig, Input, SHELL_ROLE,
@@ -29,15 +29,17 @@ use crate::utils::*;
 
 use crate::cli::Cli;
 use crate::vault::Vault;
-use anyhow::{Result, bail};
+use anyhow::{Result, anyhow, bail};
 use clap::{CommandFactory, Parser};
 use clap_complete::CompleteEnv;
-use inquire::Text;
+use client::ClientConfig;
+use inquire::{Select, Text};
 use log::LevelFilter;
 use log4rs::append::console::ConsoleAppender;
 use log4rs::append::file::FileAppender;
 use log4rs::config::{Appender, Logger, Root};
 use log4rs::encode::pattern::PatternEncoder;
+use oauth::OAuthProvider;
 use parking_lot::RwLock;
 use std::path::PathBuf;
 use std::{env, mem, process, sync::Arc};
@@ -81,6 +83,13 @@ async fn main() -> Result<()> {
 
     let log_path = setup_logger()?;
 
+    if let Some(client_arg) = &cli.authenticate {
+        let config = Config::init_bare()?;
+        let (client_name, provider) = resolve_oauth_client(client_arg.as_deref(), &config.clients)?;
+        oauth::run_oauth_flow(&provider, &client_name).await?;
+        return Ok(());
+    }
+
     if vault_flags {
         return Vault::handle_vault_flags(cli, Config::init_bare()?);
     }
@@ -504,3 +513,33 @@ fn init_console_logger(
         .build(Root::builder().appender("console").build(root_log_level))
         .unwrap()
 }
+
+fn resolve_oauth_client(
+    explicit: Option<&str>,
+    clients: &[ClientConfig],
+) -> Result<(String, impl OAuthProvider)> {
+    if let Some(name) = explicit {
+        let provider_type = oauth::resolve_provider_type(name, clients)
+            .ok_or_else(|| anyhow!("Client '{name}' not found or doesn't support OAuth"))?;
+        let provider = oauth::get_oauth_provider(provider_type).unwrap();
+        return Ok((name.to_string(), provider));
+    }
+
+    let candidates = oauth::list_oauth_capable_clients(clients);
+    match candidates.len() {
+        0 => bail!("No OAuth-capable clients configured."),
+        1 => {
+            let name = &candidates[0];
+            let provider_type = oauth::resolve_provider_type(name, clients).unwrap();
+            let provider = oauth::get_oauth_provider(provider_type).unwrap();
+            Ok((name.clone(), provider))
+        }
+        _ => {
+            let choice =
+                Select::new("Select a client to authenticate:", candidates.clone()).prompt()?;
+            let provider_type = oauth::resolve_provider_type(&choice, clients).unwrap();
+            let provider = oauth::get_oauth_provider(provider_type).unwrap();
+            Ok((choice, provider))
+        }
+    }
+}