feat: [US-016] - Add browser context (persistent profile) management

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/ralph/prd.json

@@ -263,8 +263,8 @@
         "Typecheck passes"
       ],
       "priority": 16,
-      "passes": false,
+      "passes": true,
-      "notes": ""
+      "notes": "Context CRUD is pure filesystem operations (no browser needed to be active). IDs are hex-encoded random bytes (no uuid dependency). context.json metadata file stores name+createdAt per context directory. contextId integration in browser start was already implemented in US-005."
     },
     {
       "id": "US-017",

scripts/ralph/progress.txt

@@ -41,6 +41,8 @@
 - CDP `Page.handleJavaScriptDialog` takes `{accept, promptText?}` for alert/confirm/prompt handling; no DOM setup needed
 - CDP event monitoring pattern: `Runtime.enable` + `Network.enable` in start(), subscribe via `cdp.subscribe(event)`, spawn tokio tasks to populate ring buffers; tasks auto-terminate when CDP connection closes
 - For internal-only fields in API types, use `#[serde(default, skip_serializing)]` to keep them out of JSON responses
+- Browser context management is pure filesystem CRUD; each context is a directory under `{state_dir}/browser-contexts/{id}/` with a `context.json` metadata file
+- Use hex-encoded /dev/urandom bytes for generating IDs (same pattern as telemetry.rs) to avoid adding new crate deps
 
 # Ralph Progress Log
 Started: Tue Mar 17 04:32:06 AM PDT 2026
@@ -288,3 +290,21 @@ Started: Tue Mar 17 04:32:06 AM PDT 2026
   - Background tokio::spawn tasks for event processing don't need explicit cleanup; they terminate when CDP subscription channel closes (on browser stop)
   - Added internal `request_id` field with `#[serde(skip_serializing)]` to keep it out of API responses while enabling request/response correlation
 ---
+
+## 2026-03-17 - US-016
+- Created `browser_context.rs` with context management functions: list_contexts, create_context, delete_context
+- Each context stored as a directory under `{state_dir}/browser-contexts/{id}/` with a `context.json` metadata file
+- Added `state_dir()` accessor to `BrowserRuntime` to expose the state directory path
+- Added 3 HTTP endpoints in router.rs: GET /v1/browser/contexts, POST /v1/browser/contexts (201), DELETE /v1/browser/contexts/:context_id
+- Registered `mod browser_context` in lib.rs
+- OpenAPI paths and schemas registered for all 3 endpoints and context types
+- contextId integration in POST /v1/browser/start was already implemented in US-005 (sets --user-data-dir)
+- 3 unit tests pass (create+list, delete, delete-nonexistent)
+- Files changed: browser_context.rs (new), browser_runtime.rs, router.rs, lib.rs, prd.json
+- **Learnings for future iterations:**
+  - Context management is pure filesystem operations; no browser needs to be running
+  - Use hex-encoded random bytes from /dev/urandom for IDs to avoid adding uuid dependency (same pattern as telemetry.rs)
+  - `BrowserRuntime.config.state_dir` was private; added `state_dir()` pub accessor for context module access
+  - Context types (BrowserContextInfo, BrowserContextListResponse, BrowserContextCreateRequest) were already defined in browser_types.rs from US-003
+  - `tempfile` crate is a workspace dev-dependency available via `test-utils` feature flag
+---

server/packages/sandbox-agent/src/browser_context.rs

@@ -0,0 +1,224 @@
+use std::fs;
+use std::io::Read as _;
+use std::path::{Path, PathBuf};
+
+use serde::{Deserialize, Serialize};
+
+use crate::browser_errors::BrowserProblem;
+use crate::browser_types::{BrowserContextCreateRequest, BrowserContextInfo};
+
+/// Metadata stored alongside each browser context directory.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+struct ContextMeta {
+    id: String,
+    name: String,
+    created_at: String,
+}
+
+const META_FILE: &str = "context.json";
+
+/// Return the base directory that holds all browser context directories.
+pub fn contexts_base_dir(state_dir: &Path) -> PathBuf {
+    state_dir.join("browser-contexts")
+}
+
+/// List all browser contexts stored on disk.
+pub fn list_contexts(state_dir: &Path) -> Result<Vec<BrowserContextInfo>, BrowserProblem> {
+    let base = contexts_base_dir(state_dir);
+    if !base.exists() {
+        return Ok(Vec::new());
+    }
+
+    let mut contexts = Vec::new();
+    let entries = fs::read_dir(&base).map_err(|e| {
+        BrowserProblem::start_failed(format!("failed to read contexts directory: {e}"))
+    })?;
+
+    for entry in entries {
+        let entry = match entry {
+            Ok(e) => e,
+            Err(_) => continue,
+        };
+        let path = entry.path();
+        if !path.is_dir() {
+            continue;
+        }
+        let meta_path = path.join(META_FILE);
+        if !meta_path.exists() {
+            continue;
+        }
+        let meta_bytes = match fs::read(&meta_path) {
+            Ok(b) => b,
+            Err(_) => continue,
+        };
+        let meta: ContextMeta = match serde_json::from_slice(&meta_bytes) {
+            Ok(m) => m,
+            Err(_) => continue,
+        };
+        let size_bytes = dir_size(&path);
+        contexts.push(BrowserContextInfo {
+            id: meta.id,
+            name: meta.name,
+            created_at: meta.created_at,
+            size_bytes: Some(size_bytes),
+        });
+    }
+
+    contexts.sort_by(|a, b| a.created_at.cmp(&b.created_at));
+    Ok(contexts)
+}
+
+/// Create a new browser context directory with metadata.
+pub fn create_context(
+    state_dir: &Path,
+    request: BrowserContextCreateRequest,
+) -> Result<BrowserContextInfo, BrowserProblem> {
+    let id = generate_context_id();
+    let base = contexts_base_dir(state_dir);
+    let context_dir = base.join(&id);
+
+    fs::create_dir_all(&context_dir).map_err(|e| {
+        BrowserProblem::start_failed(format!("failed to create context directory: {e}"))
+    })?;
+
+    let now = chrono::Utc::now().to_rfc3339();
+    let meta = ContextMeta {
+        id: id.clone(),
+        name: request.name.clone(),
+        created_at: now.clone(),
+    };
+
+    let meta_bytes = serde_json::to_vec_pretty(&meta).map_err(|e| {
+        BrowserProblem::start_failed(format!("failed to serialize context metadata: {e}"))
+    })?;
+
+    fs::write(context_dir.join(META_FILE), meta_bytes).map_err(|e| {
+        BrowserProblem::start_failed(format!("failed to write context metadata: {e}"))
+    })?;
+
+    Ok(BrowserContextInfo {
+        id,
+        name: request.name,
+        created_at: now,
+        size_bytes: Some(0),
+    })
+}
+
+/// Delete a browser context directory.
+pub fn delete_context(state_dir: &Path, context_id: &str) -> Result<(), BrowserProblem> {
+    let base = contexts_base_dir(state_dir);
+    let context_dir = base.join(context_id);
+
+    if !context_dir.exists() {
+        return Err(BrowserProblem::not_found(format!(
+            "browser context '{context_id}' not found"
+        )));
+    }
+
+    fs::remove_dir_all(&context_dir).map_err(|e| {
+        BrowserProblem::start_failed(format!("failed to delete context directory: {e}"))
+    })?;
+
+    Ok(())
+}
+
+/// Generate a hex-encoded random ID for a browser context.
+fn generate_context_id() -> String {
+    let mut bytes = [0u8; 16];
+    if let Ok(mut file) = fs::File::open("/dev/urandom") {
+        if file.read_exact(&mut bytes).is_ok() {
+            return hex_encode(&bytes);
+        }
+    }
+    // Fallback: timestamp + pid
+    let now = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_nanos();
+    let pid = std::process::id() as u128;
+    bytes = (now ^ (pid << 64)).to_le_bytes();
+    hex_encode(&bytes)
+}
+
+fn hex_encode(bytes: &[u8]) -> String {
+    let mut out = String::with_capacity(bytes.len() * 2);
+    for byte in bytes {
+        out.push_str(&format!("{byte:02x}"));
+    }
+    out
+}
+
+/// Recursively compute the size of a directory in bytes.
+fn dir_size(path: &Path) -> u64 {
+    let mut total = 0u64;
+    if let Ok(entries) = fs::read_dir(path) {
+        for entry in entries.flatten() {
+            let p = entry.path();
+            if p.is_dir() {
+                total += dir_size(&p);
+            } else if let Ok(meta) = p.metadata() {
+                total += meta.len();
+            }
+        }
+    }
+    total
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::TempDir;
+
+    #[test]
+    fn test_create_and_list_contexts() {
+        let tmp = TempDir::new().unwrap();
+        let state_dir = tmp.path();
+
+        // Initially empty
+        let contexts = list_contexts(state_dir).unwrap();
+        assert!(contexts.is_empty());
+
+        // Create a context
+        let info = create_context(
+            state_dir,
+            BrowserContextCreateRequest {
+                name: "test-profile".to_string(),
+            },
+        )
+        .unwrap();
+        assert_eq!(info.name, "test-profile");
+        assert!(!info.id.is_empty());
+
+        // List shows it
+        let contexts = list_contexts(state_dir).unwrap();
+        assert_eq!(contexts.len(), 1);
+        assert_eq!(contexts[0].name, "test-profile");
+        assert_eq!(contexts[0].id, info.id);
+    }
+
+    #[test]
+    fn test_delete_context() {
+        let tmp = TempDir::new().unwrap();
+        let state_dir = tmp.path();
+
+        let info = create_context(
+            state_dir,
+            BrowserContextCreateRequest {
+                name: "to-delete".to_string(),
+            },
+        )
+        .unwrap();
+
+        delete_context(state_dir, &info.id).unwrap();
+
+        let contexts = list_contexts(state_dir).unwrap();
+        assert!(contexts.is_empty());
+    }
+
+    #[test]
+    fn test_delete_nonexistent_context() {
+        let tmp = TempDir::new().unwrap();
+        let result = delete_context(tmp.path(), "nonexistent");
+        assert!(result.is_err());
+    }
+}

server/packages/sandbox-agent/src/browser_runtime.rs

@@ -637,6 +637,11 @@ impl BrowserRuntime {
         &self.streaming_manager
     }
 
+    /// Return the state directory used for browser data (contexts, logs, etc.).
+    pub fn state_dir(&self) -> &Path {
+        &self.config.state_dir
+    }
+
     /// Push a console message into the ring buffer.
     pub async fn push_console_message(&self, message: BrowserConsoleMessage) {
         let mut state = self.inner.lock().await;

server/packages/sandbox-agent/src/lib.rs

@@ -2,6 +2,7 @@
 
 mod acp_proxy_runtime;
 mod browser_cdp;
+mod browser_context;
 mod browser_errors;
 mod browser_install;
 mod browser_runtime;

server/packages/sandbox-agent/src/router.rs

@@ -307,6 +307,14 @@ pub fn build_router_with_state(shared: Arc<AppState>) -> (Router, Arc<AppState>)
         .route("/browser/dialog", post(post_v1_browser_dialog))
         .route("/browser/console", get(get_v1_browser_console))
         .route("/browser/network", get(get_v1_browser_network))
+        .route(
+            "/browser/contexts",
+            get(get_v1_browser_contexts).post(post_v1_browser_contexts),
+        )
+        .route(
+            "/browser/contexts/:context_id",
+            delete(delete_v1_browser_context),
+        )
         .route("/agents", get(get_v1_agents))
         .route("/agents/:agent", get(get_v1_agent))
         .route("/agents/:agent/install", post(post_v1_agent_install))
@@ -524,6 +532,9 @@ pub async fn shutdown_servers(state: &Arc<AppState>) {
         post_v1_browser_dialog,
         get_v1_browser_console,
         get_v1_browser_network,
+        get_v1_browser_contexts,
+        post_v1_browser_contexts,
+        delete_v1_browser_context,
         get_v1_agents,
         get_v1_agent,
         post_v1_agent_install,
@@ -635,6 +646,9 @@ pub async fn shutdown_servers(state: &Arc<AppState>) {
             BrowserNetworkQuery,
             BrowserNetworkRequest,
             BrowserNetworkResponse,
+            BrowserContextInfo,
+            BrowserContextListResponse,
+            BrowserContextCreateRequest,
             DesktopClipboardResponse,
             DesktopClipboardQuery,
             DesktopClipboardWriteRequest,
@@ -2684,6 +2698,73 @@ async fn get_v1_browser_network(
     Ok(Json(BrowserNetworkResponse { requests }))
 }
 
+/// List browser contexts (persistent profiles).
+///
+/// Returns all browser context directories with their name, creation date,
+/// and on-disk size.
+#[utoipa::path(
+    get,
+    path = "/v1/browser/contexts",
+    tag = "v1",
+    responses(
+        (status = 200, description = "Browser contexts listed", body = BrowserContextListResponse),
+        (status = 500, description = "Internal error", body = ProblemDetails)
+    )
+)]
+async fn get_v1_browser_contexts(
+    State(state): State<Arc<AppState>>,
+) -> Result<Json<BrowserContextListResponse>, ApiError> {
+    let contexts = crate::browser_context::list_contexts(state.browser_runtime().state_dir())?;
+    Ok(Json(BrowserContextListResponse { contexts }))
+}
+
+/// Create a browser context (persistent profile).
+///
+/// Creates a new browser context directory that can be passed as contextId
+/// to the browser start endpoint for persistent cookies and storage.
+#[utoipa::path(
+    post,
+    path = "/v1/browser/contexts",
+    tag = "v1",
+    request_body = BrowserContextCreateRequest,
+    responses(
+        (status = 201, description = "Browser context created", body = BrowserContextInfo),
+        (status = 500, description = "Internal error", body = ProblemDetails)
+    )
+)]
+async fn post_v1_browser_contexts(
+    State(state): State<Arc<AppState>>,
+    Json(body): Json<BrowserContextCreateRequest>,
+) -> Result<(StatusCode, Json<BrowserContextInfo>), ApiError> {
+    let info = crate::browser_context::create_context(state.browser_runtime().state_dir(), body)?;
+    Ok((StatusCode::CREATED, Json(info)))
+}
+
+/// Delete a browser context (persistent profile).
+///
+/// Removes the browser context directory and all stored data (cookies,
+/// local storage, cache, etc.).
+#[utoipa::path(
+    delete,
+    path = "/v1/browser/contexts/{context_id}",
+    tag = "v1",
+    params(
+        ("context_id" = String, Path, description = "Browser context ID")
+    ),
+    responses(
+        (status = 200, description = "Browser context deleted", body = BrowserActionResponse),
+        (status = 404, description = "Browser context not found", body = ProblemDetails),
+        (status = 500, description = "Internal error", body = ProblemDetails)
+    )
+)]
+async fn delete_v1_browser_context(
+    State(state): State<Arc<AppState>>,
+    Path(context_id): Path<String>,
+) -> Result<Json<BrowserActionResponse>, ApiError> {
+    crate::browser_context::delete_context(state.browser_runtime().state_dir(), &context_id)?;
+    Ok(Json(BrowserActionResponse { ok: true }))
+}
+
 /// Helper: get the current page URL and title via CDP Runtime.evaluate.
 async fn get_page_info_via_cdp(
     cdp: &crate::browser_cdp::CdpClient,