fix: preserve changes when diff fails

.project-docs/30-worklog/tasks/20260823-pi-product-tools-a9c4e7d2.md

@@ -98,6 +98,10 @@
   `changes.touched` ACK bridge; full diff/preview data stays Main-only; and
   untracked reads plus previews are both limited to 8 KiB while size/mtime
   detect equal-length changes beyond that window.
+- Closed the follow-up review finding by making per-candidate Git diff failure,
+  non-zero exit, or output-limit rejection non-fatal: the Main snapshot keeps
+  the changed relative path and status while omitting only the unavailable
+  diff. The regression uses the same `Git output is too large` failure shape.
 - The packaged smoke now has two halves: a staged production-closure Pi
   process check and a controlled Electron-Node authenticated bridge check that
   actually executes browser status/screenshot attachment and game asset
@@ -114,7 +118,7 @@
   `Makelore/index.tsx`; none are in this task's changed scope).
 - Final focused PI-090/Pi projection/bridge/game/resource suite: 12 files,
   71 tests passed. The planner's five minimal failure shapes are also covered
-  by the 4-file 19-test tracker/bridge/runtime subset.
+  by the final 4-file 20-test tracker/bridge/runtime subset.
 - Final serial full suite
   (`corepack pnpm vitest run --maxWorkers=1 --no-file-parallelism`): 203 files,
   2226 tests passed, 2 skipped. Two preceding parallel full-suite runs each