Fix Claude test credential setup

REPORT-claude-credentials-failure.md

@@ -0,0 +1,20 @@
+# Claude test failures: real root cause
+
+## Finding
+The Claude E2E tests were not failing due to missing credentials in general; they were failing because the tests overwrite `CLAUDE_CONFIG_DIR` with a fresh temp directory and do **not** carry forward Claude's credential store. This removes the SDK's `.credentials.json` file when the SDK is running in plaintext storage mode (common in CI), so the SDK cannot load OAuth/API credentials even though the user has valid credentials in the default config directory.
+
+## Evidence
+- The Claude agent SDK stores credentials in a file named `.credentials.json` under its config directory:
+  - `node_modules/@anthropic-ai/claude-agent-sdk/cli.js` shows the plaintext credential store path as `join(storageDir, ".credentials.json")`.
+- The tests set `process.env.CLAUDE_CONFIG_DIR` to a temp dir in:
+  - `packages/server/src/server/agent/providers/claude-agent.test.ts` (via `useTempClaudeConfigDir`)
+  - `packages/server/src/server/agent/agent-mcp.e2e.test.ts`
+- The temp config dir is populated with settings only, so the SDK can't find `.credentials.json` after the override.
+
+## Fix summary
+- Copy `.credentials.json` from the original config directory (explicit `CLAUDE_CONFIG_DIR` or `~/.claude`) into the temp config dir used by tests.
+- Remove the hardcoded env-var-only credential precheck so tests fail with the *real* SDK error if credentials are genuinely absent.
+
+## Files updated
+- `packages/server/src/server/agent/providers/claude-agent.test.ts`
+- `packages/server/src/server/agent/agent-mcp.e2e.test.ts`