[Bug] Make Full Skin apply diagnose target/version failures immediately

[rwang23]

Reported symptom

On another Windows machine, Apply & Keep Full Skin reported that it could not apply the Full Skin and mentioned a POST/CDP access-denied error. The original complete visible diagnostic, exact selected channel/version, and process state were not captured, so this issue does not assume a particular CDP or Origin-policy root cause.

v0.3.2 behavior

The former train-level compatibility gate was replaced with a per-device, exact-version probe:

• An explicit Apply may probe the exact installed Stable or Beta target on that device; it is not rejected merely because its version differs from the pinned Beta evidence build.
• Automatic replay remains conservative: it runs only for the same target/version that has already completed a successful local loopback probe.
• The controller still verifies the selected package, the loopback listener owner, and an app:// target before applying the declarative runtime.
• Recoverable controller failures show a safe retry state. Terminal launch/CDP failures are returned immediately as a sanitized visible diagnostic instead of timing out behind a generic failure.

Acceptance criteria

• Explicit Apply probes an exact locally detected Stable or Beta target instead of using a static version-train allowlist.
• Automatic replay requires the same locally verified target/version.
• The CDP path remains limited to the selected package, loopback debugging port, and app:// target.
• Terminal failures distinguish themselves from retriable failures and surface a visible diagnostic promptly.
• Rust and repository regression tests cover the version and failure-state behavior.
• The v0.3.2 release documents the support and diagnostic behavior.
• Confirm the reported remote Windows machine can apply successfully or provide its terminal diagnostic for a targeted follow-up.

Reporter information still needed

If the problem persists after v0.3.2, please attach the complete visible diagnostic text, Theme Manager version, Windows version and CPU, selected ChatGPT/Codex channel and version, and whether the target app was already open. Do not attach chats, tokens, or private application data.

[rwang23]

The v0.3.2 remediation is present on current main (e2ed6e8) and the current regression suite passed on 2026-07-27. The only unchecked acceptance item is confirmation from the originally affected Windows machine, or a sanitized terminal diagnostic for a targeted follow-up.

Keeping this Issue open as the evidence/triage record. We should not guess at another CDP or Origin-policy change without that report.