feat(native-agent): Anthropic OAuth (Claude Pro/Max) login for openab-agent

Cargo.toml

@@ -1,5 +1,6 @@
 [workspace]
 members = ["crates/openab-core", "crates/openab-gateway"]
+exclude = ["openab-agent"]
 
 [package]
 name = "openab"

crates/openab-core/src/format.rs

@@ -319,7 +319,7 @@ mod tests {
         for (i, chunk) in chunks.iter().enumerate() {
             let fence_count = chunk.lines().filter(|l| l.starts_with("```")).count();
             assert!(
-                fence_count % 2 == 0,
+                fence_count.is_multiple_of(2),
                 "chunk {i} has unbalanced fences ({fence_count}):\n{chunk}"
             );
         }

crates/openab-gateway/src/adapters/wecom.rs

@@ -137,7 +137,7 @@ fn decrypt_message(
         .decode(encrypted)
         .map_err(|e| anyhow::anyhow!("base64 decode failed: {e}"))?;
 
-    if cipher_bytes.is_empty() || cipher_bytes.len() % 16 != 0 {
+    if cipher_bytes.is_empty() || !cipher_bytes.len().is_multiple_of(16) {
         anyhow::bail!("ciphertext length {} not a multiple of 16", cipher_bytes.len());
     }
 

docs/native-agent.md

@@ -27,17 +27,41 @@ openab-agent
 env = { OPENAB_AGENT_OPENAI_MODEL = "gpt-5.4-mini" }
 ```
 
+### Configuration file (config.json)
+
+A small JSON file next to `auth.json` (default `<auth dir>/config.json`,
+overridable with `OPENAB_CONFIG_PATH`) declares the default model and params, so
+a deployment can set them in a file instead of only via env vars. **Secrets never
+go here** — credentials stay in the locked `auth.json` store.
+
+```jsonc
+{
+  "model": "anthropic/claude-sonnet-4-6",  // single provider/model string
+  "max_tokens": 8192                         // optional
+}
+```
+
+Resolution is **env-over-config**: `OPENAB_AGENT_MODEL` / `OPENAB_AGENT_MAX_TOKENS`
+override the file, so a pod's injected env stays authoritative over a baked
+config. A missing file is fine (empty config); a malformed file is logged and
+ignored (the agent then falls back to env / built-in defaults). Unknown keys are
+tolerated for forward-compatibility.
+
 ## Environment Variables
 
 | Variable | Default | Description |
 |----------|---------|-------------|
+| `OPENAB_AGENT_MODEL` | — (required for Anthropic) | Anthropic model id, optionally `provider/`-qualified (e.g. `claude-opus-4-8`, `anthropic/claude-opus-4-8`). No hardcoded default — dateless 4.6+ IDs are fixed canonical IDs that retire each generation, so the agent fails loud if unset rather than pin a model that will eventually 404. Overrides `model` in [config.json](#configuration-file-configjson). |
 | `OPENAB_AGENT_OPENAI_MODEL` | `gpt-5.4-mini` | Model to use (must be supported by your ChatGPT plan — see [Supported Models](#supported-models-chatgpt-subscription)) |
 | `OPENAB_AGENT_OPENAI_BASE_URL` | `https://chatgpt.com/backend-api` | API base URL |
 | `OPENAB_AGENT_PROVIDER` | auto-detect | Force provider (`anthropic`, `openai`, `codex`) |
-| `OPENAB_AGENT_MAX_TOKENS` | `8192` | Max output tokens |
-| `OPENAB_AGENT_OAUTH_CLIENT_ID` | Pi's client | Custom OAuth client ID |
+| `OPENAB_AGENT_MAX_TOKENS` | `8192` | Max output tokens. Overrides `max_tokens` in config.json. |
+| `OPENAB_AGENT_OAUTH_CLIENT_ID` | Pi's client | Custom Codex OAuth client ID |
+| `OPENAB_AGENT_ANTHROPIC_CLIENT_ID` | Claude Code's client | Custom Anthropic OAuth client ID |
 | `OPENAB_AGENT_MAX_TOOL_LOOPS` | `50` | Max tool-call iterations per prompt before the agent gives up |
-| `ANTHROPIC_API_KEY` | — | Anthropic API key (alternative to OAuth) |
+| `ANTHROPIC_API_KEY` | — | Anthropic API key. Highest-precedence Anthropic credential (see [Anthropic credentials](#anthropic-credentials)). |
+| `CLAUDE_CODE_OAUTH_TOKEN` | — | Pre-provisioned long-lived Claude Pro/Max subscription token (from `claude setup-token`). Fleet route — no interactive login, no `auth.json` write. |
+| `OPENAB_CONFIG_PATH` | `<auth dir>/config.json` | Override the config-file path. |
 
 ## Authentication
 
@@ -69,13 +93,33 @@ openab-agent auth codex-device
 
 Note: Device flow currently has limited scopes and may not work with all models.
 
-### API Key (Anthropic)
+### Anthropic credentials
 
-```bash
-export ANTHROPIC_API_KEY=sk-ant-...
-```
+Three ways to authenticate Anthropic, resolved in this **precedence** (ADR §5.3):
+
+1. **API key** — `export ANTHROPIC_API_KEY=sk-ant-...`. No login; auto-detected.
+2. **Pre-provisioned subscription token (fleet route)** — `export CLAUDE_CODE_OAUTH_TOKEN=...`
+   (mint once with `claude setup-token`; ~1-year Claude Pro/Max token). Sent as a
+   `Bearer` subscription token with the Claude Code identity headers — no
+   interactive login, no `auth.json` write, no refresh. Recommended for pods (inject
+   as a k8s secret).
+3. **Interactive Claude Pro/Max OAuth** — browser PKCE login, refreshed from the
+   stored `anthropic-oauth` tenant in `auth.json`:
+
+   ```bash
+   openab-agent auth anthropic-oauth            # browser
+   openab-agent auth anthropic-oauth --no-browser  # paste code#state
+   ```
+
+A higher-precedence source's own errors (e.g. a key set but no model) surface
+rather than silently falling through to a lower one.
+
+### Adding an OAuth vendor
 
-No login needed — set the env var and the agent auto-detects it.
+Subscription-OAuth providers are declared as a single `OAuthVendor` descriptor
+(`auth.rs`, ADR §5.1) — namespace, client id, authorize/token URLs, redirect,
+scope, token-body encoding. The shared PKCE/device/refresh driver reads the
+descriptor, so a new vendor is a new descriptor, not a new hand-rolled flow.
 
 ## Custom System Prompt
 

openab-agent/src/acp.rs

@@ -204,7 +204,7 @@ impl AcpServer {
         // through `out_tx` into this one drain task, preserving the
         // one-writer invariant the HostBridge relies on.
         let (out_tx, mut out_rx) = mpsc::unbounded_channel::<String>();
-        tokio::spawn(async move {
+        let drain = tokio::spawn(async move {
             let mut stdout = io::stdout();
             while let Some(line) = out_rx.recv().await {
                 let _ = writeln!(stdout, "{}", line);
@@ -268,6 +268,16 @@ impl AcpServer {
                 let _ = out_tx.send(line);
             }
         }
+
+        // Shutdown: stdin hit EOF and the dispatch loop ended. Drop our senders
+        // so the drain task can flush any queued output and finish before this
+        // returns — otherwise `#[tokio::main]` aborts the detached drain on
+        // return and the last response can be lost (the ACP `initialize` smoke
+        // test depends on this). Bounded await so a lingering sender (e.g. an
+        // MCP background task holding an `out_tx` clone) can't wedge shutdown.
+        drop(bridge);
+        drop(out_tx);
+        let _ = tokio::time::timeout(std::time::Duration::from_secs(2), drain).await;
     }
 
     fn handle_initialize(&self, id: u64) -> String {
@@ -297,15 +307,18 @@ impl AcpServer {
         let provider_choice = self
             .active_provider
             .clone()
-            .or_else(|| std::env::var("OPENAB_AGENT_PROVIDER").ok())
-            .unwrap_or_default();
+            .unwrap_or_else(crate::llm::resolve_provider_choice);
         let model_override = self.active_model.as_deref();
         let (provider, active_provider): (Box<dyn crate::llm::LlmProvider>, &str) =
             match provider_choice.as_str() {
-                "anthropic" => {
-                    let res = match model_override {
-                        Some(m) => AnthropicProvider::from_env_with_model(m),
-                        None => AnthropicProvider::from_env(),
+                // `auto*` covers both ANTHROPIC_API_KEY and a stored Claude
+                // subscription OAuth token; `anthropic-oauth` forces the latter.
+                "anthropic" | "anthropic-oauth" | "claude" => {
+                    let res = match (provider_choice.as_str(), model_override) {
+                        ("anthropic", Some(m)) => AnthropicProvider::auto_with_model(m),
+                        ("anthropic", None) => AnthropicProvider::auto(),
+                        (_, Some(m)) => AnthropicProvider::from_oauth_store_with_model(m),
+                        (_, None) => AnthropicProvider::from_oauth_store(),
                     };
                     match res {
                         Ok(p) => (Box::new(p), "anthropic"),
@@ -323,10 +336,10 @@ impl AcpServer {
                     }
                 }
                 _ => {
-                    // Auto-detect: try API key first, then OAuth token
+                    // Auto-detect: Anthropic (API key or OAuth) first, then codex.
                     let anthropic_res = match model_override {
-                        Some(m) => AnthropicProvider::from_env_with_model(m),
-                        None => AnthropicProvider::from_env(),
+                        Some(m) => AnthropicProvider::auto_with_model(m),
+                        None => AnthropicProvider::auto(),
                     };
                     match anthropic_res {
                         Ok(p) => (Box::new(p), "anthropic"),
@@ -343,7 +356,7 @@ impl AcpServer {
                                     return self.error_response(
                                         id,
                                         -32000,
-                                        &format!("No credentials: set ANTHROPIC_API_KEY or run `openab-agent auth codex-oauth`. {e}"),
+                                        &format!("No credentials: set ANTHROPIC_API_KEY, or run `openab-agent auth anthropic-oauth` / `openab-agent auth codex-oauth`. {e}"),
                                     )
                                 }
                             }
@@ -352,27 +365,13 @@ impl AcpServer {
                 }
             };
 
+        // The provider already resolved its model (explicit override →
+        // OPENAB_AGENT_MODEL, validated at construction). Use it as the
+        // authoritative reported model instead of a separate hardcoded default.
+        let model_name = provider.model().to_string();
         let agent = Agent::new_boxed(provider, self.working_dir.clone(), self.mcp_manager.clone());
         self.sessions.insert(session_id.clone(), agent);
 
-        let model_name = self
-            .active_model
-            .clone()
-            .or_else(|| {
-                if active_provider == "openai" {
-                    std::env::var("OPENAB_AGENT_OPENAI_MODEL").ok()
-                } else {
-                    None
-                }
-            })
-            .or_else(|| std::env::var("OPENAB_AGENT_MODEL").ok())
-            .unwrap_or_else(|| {
-                if active_provider == "anthropic" {
-                    "claude-sonnet-4-20250514".to_string()
-                } else {
-                    "gpt-5.4-mini".to_string()
-                }
-            });
         self.active_model = Some(model_name.clone());
         self.active_provider = Some(active_provider.to_string());
         self.model_options = Self::available_models().await;
@@ -425,13 +424,11 @@ impl AcpServer {
             self.model_options = Self::available_models().await;
         }
 
-        let model_name = self.active_model.clone().unwrap_or_else(|| {
-            if self.active_provider.as_deref() == Some("openai") {
-                "gpt-5.4-mini".to_string()
-            } else {
-                "claude-sonnet-4-20250514".to_string()
-            }
-        });
+        // Report the loaded session's actual model (no hardcoded default).
+        let model_name = self
+            .active_model
+            .clone()
+            .unwrap_or_else(|| self.sessions[session_id].provider_model());
 
         self.ok_response(
             id,
@@ -457,7 +454,9 @@ impl AcpServer {
 
     fn static_available_models() -> Vec<ModelOption> {
         let mut models = Vec::new();
-        if std::env::var("ANTHROPIC_API_KEY").is_ok() {
+        if std::env::var("ANTHROPIC_API_KEY").is_ok()
+            || crate::auth::load_tokens_for(crate::auth::ANTHROPIC_NAMESPACE).is_ok()
+        {
             models.extend(Self::static_anthropic_models());
         }
         if crate::auth::load_tokens().is_ok() {
@@ -595,11 +594,15 @@ impl AcpServer {
 
         // Rebuild the current session's provider so the switch takes effect immediately
         if !session_id.is_empty() && self.sessions.contains_key(session_id) {
+            // Preserve the session's auth mode: an OAuth-forced session must not
+            // silently fall back to ANTHROPIC_API_KEY (which `auto_*` prefers).
+            let session_is_oauth = self.sessions[session_id].provider_is_oauth();
             let new_provider: Result<Box<dyn crate::llm::LlmProvider>, String> = match provider_name
             {
-                "anthropic" => {
-                    AnthropicProvider::from_env_with_model(value).map(|p| Box::new(p) as _)
+                "anthropic" if session_is_oauth => {
+                    AnthropicProvider::from_oauth_store_with_model(value).map(|p| Box::new(p) as _)
                 }
+                "anthropic" => AnthropicProvider::auto_with_model(value).map(|p| Box::new(p) as _),
                 _ => crate::llm::OpenAiProvider::from_auth_store_with_model(value)
                     .map(|p| Box::new(p) as _),
             };
@@ -679,10 +682,14 @@ mod tests {
     #[tokio::test]
     async fn test_session_new() {
         let _guard = ENV_LOCK.lock().unwrap();
-        // Set a fake key so from_env() succeeds in CI
-        unsafe { std::env::set_var("ANTHROPIC_API_KEY", "test-key") };
+        // Set a fake key + model so provider construction succeeds in CI
+        unsafe {
+            std::env::set_var("ANTHROPIC_API_KEY", "test-key");
+            std::env::set_var("OPENAB_AGENT_MODEL", "claude-sonnet-4-6");
+        }
         let mut server = AcpServer::new();
         let resp_str = server.handle_session_new(2).await;
+        unsafe { std::env::remove_var("OPENAB_AGENT_MODEL") };
         let resp: Value = serde_json::from_str(&resp_str).unwrap();
         assert_eq!(resp["jsonrpc"], "2.0");
         assert_eq!(resp["id"], 2);
@@ -692,6 +699,7 @@ mod tests {
         assert!(!config_options.is_empty());
         assert_eq!(config_options[0]["id"], "model");
         assert_eq!(config_options[0]["category"], "model");
+        assert_eq!(config_options[0]["currentValue"], "claude-sonnet-4-6");
         assert!(!config_options[0]["options"].as_array().unwrap().is_empty());
     }
 
@@ -789,6 +797,30 @@ mod tests {
             .contains("ANTHROPIC_API_KEY"));
     }
 
+    #[tokio::test]
+    async fn test_session_new_requires_model() {
+        // No hardcoded default: a forced anthropic provider without
+        // OPENAB_AGENT_MODEL must fail loud.
+        let _guard = ENV_LOCK.lock().unwrap();
+        unsafe {
+            std::env::set_var("OPENAB_AGENT_PROVIDER", "anthropic");
+            std::env::set_var("ANTHROPIC_API_KEY", "test-key");
+            std::env::remove_var("OPENAB_AGENT_MODEL");
+        }
+        let mut server = AcpServer::new();
+        let resp_str = server.handle_session_new(7).await;
+        unsafe {
+            std::env::remove_var("ANTHROPIC_API_KEY");
+            std::env::remove_var("OPENAB_AGENT_PROVIDER");
+        }
+        let resp: Value = serde_json::from_str(&resp_str).unwrap();
+        assert!(resp["error"].is_object());
+        assert!(resp["error"]["message"]
+            .as_str()
+            .unwrap()
+            .contains("no model configured"));
+    }
+
     #[test]
     fn test_set_config_option_accepts_cached_dynamic_model() {
         let mut server = AcpServer::new();
@@ -847,11 +879,15 @@ mod tests {
     #[tokio::test]
     async fn test_model_switch_preserves_session_history() {
         let _guard = ENV_LOCK.lock().unwrap();
-        unsafe { std::env::set_var("ANTHROPIC_API_KEY", "test-key") };
+        unsafe {
+            std::env::set_var("ANTHROPIC_API_KEY", "test-key");
+            std::env::set_var("OPENAB_AGENT_MODEL", "claude-sonnet-4-6");
+        }
         let mut server = AcpServer::new();
 
         // Create a session
         let resp_str = server.handle_session_new(10).await;
+        unsafe { std::env::remove_var("OPENAB_AGENT_MODEL") };
         let resp: Value = serde_json::from_str(&resp_str).unwrap();
         let session_id = resp["result"]["sessionId"].as_str().unwrap().to_string();
 
@@ -918,7 +954,7 @@ mod tests {
 
         // Insert a dummy session using anthropic key
         unsafe { std::env::set_var("ANTHROPIC_API_KEY", "test-key") };
-        let provider = AnthropicProvider::from_env_with_model("claude-sonnet-4-20250514").unwrap();
+        let provider = AnthropicProvider::auto_with_model("claude-sonnet-4-20250514").unwrap();
         let agent = Agent::new_boxed(Box::new(provider), "/tmp".to_string(), None);
         server.sessions.insert("test-session".to_string(), agent);
 
@@ -954,11 +990,15 @@ mod tests {
     #[tokio::test]
     async fn test_session_load_returns_config_options() {
         let _guard = ENV_LOCK.lock().unwrap();
-        unsafe { std::env::set_var("ANTHROPIC_API_KEY", "test-key") };
+        unsafe {
+            std::env::set_var("ANTHROPIC_API_KEY", "test-key");
+            std::env::set_var("OPENAB_AGENT_MODEL", "claude-sonnet-4-6");
+        }
         let mut server = AcpServer::new();
 
         // Create a session first
         let new_resp_str = server.handle_session_new(10).await;
+        unsafe { std::env::remove_var("OPENAB_AGENT_MODEL") };
         let new_resp: Value = serde_json::from_str(&new_resp_str).unwrap();
         let session_id = new_resp["result"]["sessionId"].as_str().unwrap();
 

openab-agent/src/agent.rs

@@ -107,6 +107,18 @@ impl Agent {
         self.provider = provider;
     }
 
+    /// True if the current provider authenticates via OAuth. Used on model
+    /// switch to rebuild with the same auth mode.
+    pub fn provider_is_oauth(&self) -> bool {
+        self.provider.is_oauth()
+    }
+
+    /// The model id the current provider will use. Authoritative source for the
+    /// session's reported model (avoids a separate hardcoded default).
+    pub fn provider_model(&self) -> String {
+        self.provider.model().to_string()
+    }
+
     /// Update working directory and rebuild system prompt.
     pub fn set_working_dir(&mut self, cwd: String) {
         self.system_prompt = Self::build_system_prompt(&cwd, self.mcp_manager.as_ref());