#3357: report unexpected desktop exits with local diagnostics

docs/testing.md

@@ -112,3 +112,24 @@ and line instead of being discarded. `--fail-over PCT` requires the same run key
 successful latest runs, and at least one comparable resource metric per run. Failed latest runs,
 missing coverage, empty results and wall-time-only measurements cannot pass the gate. Omit
 `--fail-over` for an exploratory partial comparison; failed latest runs remain visible.
+
+## Unexpected desktop exit diagnostics
+
+The desktop starts a separate, lightweight reporter before loading fonts, projects or the GPU.
+A normal exit (including a handled startup error) sends a clean marker only after desktop
+teardown. An abort or other unexpected process termination closes the pipe without that marker.
+The helper saves a local report under the session log folder's `Crash Reports` directory and
+shows a native error dialog. Control-server launches save the report without a modal dialog.
+Reports contain version/platform and at most the last 64 KiB of the matching session's log.
+Logging filters and the session file size cap can omit later events from that tail.
+They are never uploaded automatically. Review logs for private project paths before sharing.
+
+Run `cargo test -p effectcraft crash_report::tests` for bounded protocol, normal shutdown,
+actual subprocess abort, unrelated child handles, concurrent sessions, missing log/helper,
+log rotation and report-write failure coverage. The three ignored tests are subprocess entry
+points launched by these tests, not manual tests.
+
+This is diagnosis, not memory recovery: a pipe closing does not prove an out-of-memory failure
+or provide the process's exit code. System-wide exhaustion, killing the whole process tree,
+or an unavailable native dialog service can also prevent the helper from reporting. Existing
+auto-save recovery remains responsible for restoring previously saved work.