[Sunrisepeak]

CLion 0.2.0 can miss its bundled backend when the plugin class loader supplies no CodeSource URL. It then falls back to an external backend, potentially surfacing an unknown-method notification. Backend completion can also be suppressed during indexing, Cache can open empty, and native debugging creates a process without starting the target.

Resolve the installation through the public plugin-aware class loader descriptor, validate protocol 2 before custom requests, and log startup failures with backend source and RPC method/code. Enable index-independent backend completion, refresh views through content selection, and start the native Cidr debugger process inside the session starter.

Add actual packaged-plugin CI on stable CLion 2026.1.5.2 and 2026.2.4.1 alongside Plugin Verifier. Both IDEs install the same canonical ZIP and pinned mcppls 0.0.19. The scenario uses a Unicode/space project path and checks offered actions and forwarding targets, actual build/run/test, compiler-error console output, build/test failure and recovery, native test results, native debug launch and completion, mouse tab selection, manifest completion insertion, and cache inventory. Only public assertion reports are uploaded.

Validation:

• The original Marketplace 0.2.0 ZIP reproduces missing bundled-backend lookup in a full official CLion 2026.1.5.2 distribution. The actual McppSession CodeSource location is null.
• One diagnostic patched ZIP passes the same 23 checks on both stable IDEs. The backend bundle and runners remain byte-identical. Earlier controlled runs also verify manifest completion during indexing. This package is an experiment; canonical Gradle package CI remains required.
• Verifier 1.411 reports both stable IDE builds compatible with zero internal API usages, including the debugger change. Existing deprecated, scheduled-removal and experimental warnings remain.
• Protocol compatibility unit tests, integration-test compilation, Actionlint and whitespace checks pass.
• The previous canonical run passed its other 23 checks. Both new stable jobs stopped before IDE startup because the xlings installer tried to read /dev/tty. The reusable workflow now declares XLINGS_NON_INTERACTIVE itself; a new run is active.

Breakpoints, variables, stepping, stop, graph rendering, settings and further editor/recovery flows remain under investigation. Linux results do not establish native Windows/macOS GUI behavior. The accompanying design record lists the coverage boundaries and remaining cases. The user log establishes xlings fallback but not the external backend version; no private user logs, usernames, project names or local paths are included.

Related: mcpp-community/mcpp#885