fix: security hardening across all layers (#35)

* fix: comprehensive security hardening across all layers

Critical:
- Replace --dangerously-skip-permissions with explicit tool allowlist
  via settings.json (Claude Code bridge)
- Constant-time token comparison (subtle crate) in web auth and
  orchestrator auth to prevent timing attacks

High:
- Revoke tokens and clean up handles on container creation failure
- Drop SETUID/SETGID capabilities from containers (keep only CHOWN)
- Disable redirect following in HTTP tool and WASM wrapper (SSRF)
- Reject URL userinfo (@) in WASM allowlist parser (host confusion)
- Fix binary body bypassing leak detection (from_utf8 -> from_utf8_lossy)
- Protect identity files from LLM overwrites (prompt injection defense)
- Prevent tool shadowing: built-in tools cannot be replaced dynamically
- User-scoped job APIs: list/detail/cancel/restart/prompt/events/files
- CORS restricted to localhost origins, WebSocket origin validation
- Sandbox shell fail-closed: no silent fallback to unsandboxed execution
- Scrub secrets from log broadcaster before SSE broadcast
- XSS sanitization on rendered markdown in web UI
- WASM epoch ticker thread so timeout deadlines actually fire

Medium:
- Cap state transition history at 200 entries
- SSE/WebSocket connection limit (100 max)
- Request body size limit (1MB)
- Response body size limit enforcement in WASM HTTP
- UTF-8 safe string truncation (routine engine, shell tool)
- Fix PolicyAction::Sanitize to actually run the sanitizer
- TOCTOU fix in scheduler and context manager (hold write lock)
- Project file serving moved behind auth
- Path traversal guard on project_id
- Session file permissions set to 0600 on unix
- AtomicUsize for routine running_count (panic-safe)
- Completion detection hardened against false positives and tool injection
- Tool output no longer drives job completion (only LLM response)

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address security review findings across all layers

- Fix path traversal sandbox bypass via lexical normalization (file.rs)
- Fix SSRF via DNS rebinding with pre-request hostname resolution (http.rs)
- Add token budget enforcement on LLM calls (reasoning.rs, state.rs)
- Fix cross-user chat history leak with ownership verification (store.rs, server.rs)
- Add sliding-window rate limiter on gateway chat endpoint (server.rs)
- Harden extension install: HTTPS-only, 50MB cap, WASM magic validation (manager.rs)
- Add destructive command blocklist that overrides shell auto-approval (shell.rs)
- Add 5MB response body size cap to HTTP tool (http.rs)

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* refactor: deduplicate shared helpers and remove dead code

Extract floor_char_boundary and llm_signals_completion into src/util.rs,
unifying diverging phrase lists from agent/worker.rs and worker/runtime.rs.
Remove dead RespondResult::usage(), duplicate PROTECTED_IDENTITY_FILES
constant, double LeakDetector scanning in WebLogLayer, and invalid
0.0.0.0 origin from WebSocket allow list.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address PR review findings and CI test failures

- Fix record_failed_approve: .truncate(true) wiped the attempts file
  before reading, so failed pairing attempts never accumulated and
  rate limiting never triggered.
- Guard wizard WASM test: skip gracefully when channel build artifacts
  are absent (CI doesn't compile wasm32-wasip2 targets).
- Fix DNS rebinding check: use port 0 instead of hardcoded 443, since
  the port is irrelevant for hostname resolution.
- Remove hardcoded CORS port 3001: the dynamic addr.port() entries
  already cover the actual server port.
- Require WebSocket Origin header: reject connections that omit it
  entirely, since browsers always send Origin for WS upgrades and a
  missing header indicates a non-browser client bypassing the check.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address second round of PR review findings

- store.rs: reintroduce file locking around read-modify-write in
  record_failed_approve (concurrent callers could clobber each other).
- sse.rs: replace load+check+fetch_add with atomic fetch_update in both
  subscribe_raw() and subscribe() to prevent overshooting max_connections.
- ws.rs: decrement WS tracker before early return when subscribe_raw()
  returns None (connection limit reached), fixing a counter leak.
- server.rs: parse WS Origin host exactly instead of prefix matching,
  preventing bypass via crafted origins like http://localhost.evil.com.
- workspace_integration.rs: skip tests gracefully when Postgres is
  unreachable instead of panicking (fixes 10 CI failures).

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: add Origin header to WS integration tests

The Origin header requirement added in a3b0190 broke the WS gateway
integration tests. Test clients now send Origin: http://127.0.0.1:{port}
to match the server's localhost validation.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>

src/extensions/manager.rs

@@ -461,7 +461,16 @@ impl ExtensionManager {
         name: &str,
         url: &str,
     ) -> Result<InstallResult, ExtensionError> {
-        // Download the WASM binary
+        // Require HTTPS to prevent downgrade attacks
+        if !url.starts_with("https://") {
+            return Err(ExtensionError::InstallFailed(
+                "Only HTTPS URLs are allowed for extension downloads".to_string(),
+            ));
+        }
+
+        // 50 MB cap to prevent disk-fill DoS
+        const MAX_WASM_SIZE: usize = 50 * 1024 * 1024;
+
         let client = reqwest::Client::builder()
             .timeout(std::time::Duration::from_secs(60))
             .build()
@@ -480,11 +489,36 @@ impl ExtensionManager {
             )));
         }
 
+        // Check Content-Length header before downloading the full body
+        if let Some(len) = response.content_length() {
+            if len as usize > MAX_WASM_SIZE {
+                return Err(ExtensionError::InstallFailed(format!(
+                    "WASM binary too large ({} bytes, max {} bytes)",
+                    len, MAX_WASM_SIZE
+                )));
+            }
+        }
+
         let bytes = response
             .bytes()
             .await
             .map_err(|e| ExtensionError::DownloadFailed(e.to_string()))?;
 
+        if bytes.len() > MAX_WASM_SIZE {
+            return Err(ExtensionError::InstallFailed(format!(
+                "WASM binary too large ({} bytes, max {} bytes)",
+                bytes.len(),
+                MAX_WASM_SIZE
+            )));
+        }
+
+        // Basic WASM magic number check (\0asm)
+        if bytes.len() < 4 || &bytes[..4] != b"\0asm" {
+            return Err(ExtensionError::InstallFailed(
+                "Downloaded file is not a valid WASM binary (bad magic number)".to_string(),
+            ));
+        }
+
         // Ensure tools directory exists
         tokio::fs::create_dir_all(&self.wasm_tools_dir)
             .await
@@ -497,9 +531,10 @@ impl ExtensionManager {
             .map_err(|e| ExtensionError::InstallFailed(e.to_string()))?;
 
         tracing::info!(
-            "Installed WASM tool '{}' ({} bytes) to {}",
+            "Installed WASM tool '{}' ({} bytes) from {} to {}",
             name,
             bytes.len(),
+            url,
             wasm_path.display()
         );