[P1][macos-openworlds] WKWebView can blank the app when OpenWorlds loads without trailing slash

[100yenadmin]

Summary

The macOS WKWebView can show a blank OpenWorlds surface when Swift navigates to
/openworlds without a trailing slash. The OpenWorlds bundle uses relative asset
URLs like styles.css, app.jsx, and vendor/react-18.3.1.development.js.
When the browser treats /openworlds as a file path, those assets resolve from
/ instead of /openworlds/.

Release Impact

This makes the new native app look broken even though the same URL may appear to
work when manually corrected in Safari. It directly blocks the OpenWorlds-as-app
rollout because the main window can render blank while Safari renders the design.

Architecture Invariant Violated

OpenWorlds must be the normal in-app play surface. The native app must not rely on
manual Safari correction or a user knowing to add a slash.

Evidence

Relevant code paths:

• macos/ClawDnDApp/Sources/ClawDnDApp/Models/LocalEndpoint.swift
• viewer/server.py
• viewer/tests/test_openworlds_static.py

Current behavior to guard:

Swift URL: http://127.0.0.1:<port>/openworlds
Expected canonical URL: http://127.0.0.1:<port>/openworlds/

Repro

1. Launch the app.
2. Navigate the embedded WKWebView to /openworlds.
3. Observe a blank surface or missing styling/scripts.
4. Manually open /openworlds/ and observe the designed UI.

Suspected Root Cause

LocalEndpoint.openWorldsURL appends openworlds without preserving directory
semantics, and the viewer did not canonicalize /openworlds to /openworlds/.

Fix Options

Minimal patch:

• Make Swift construct /openworlds/.
• Redirect /openworlds to /openworlds/ in viewer/server.py.
• Add a route regression.

Broader hardening:

• Add endpoint readiness and canonical-route tests for every app surface.
• Make the app wait for /openworlds/ before navigation.

Recommended Solution

Take the minimal patch now, then include readiness waiting in the OpenWorlds host
PR.

Acceptance Criteria

• GET /openworlds returns 301 or 302 to /openworlds/.
• LocalEndpoint.openWorldsURL includes the trailing slash.
• WKWebView loads OpenWorlds assets correctly.

Focused Validation

python3 -m unittest viewer.tests.test_openworlds_static -q
python3 -m py_compile viewer/server.py
swift build --package-path macos/ClawDnDApp
git diff --check

Original-Agent Handoff

Inspect first:

• LocalEndpoint.openWorldsURL
• _Handler.do_GET OpenWorlds route handling in viewer/server.py
• OpenWorldsStaticRouteTests

[coderabbitai]

🔗 Related PRs

#124 - docs(openworlds): add fidelity and asset contract [merged]
#126 - feat(macos): open OpenWorlds play surface [merged]
#127 - feat(viewer): bind OpenWorlds campaigns to local state [merged]

---

📝 Issue Planner

_{Check the box below or use the @coderabbitai plan command to generate an implementation plan and prompts that you can use with your favorite coding assistant.}

• Create Plan

---

🧪 Issue enrichment is currently in open beta.

You can configure auto-planning by selecting labels in the issue_enrichment configuration.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!

[100yenadmin]

Already fixed on main: GET /openworlds sends a 302 to /openworlds/ (query preserved) via _redirect in viewer/server.py (commit f3d0199). WKWebView-blank-on-no-trailing-slash resolved.