[woksin]

Fixed

• A guarded action whose command fails now shows the command's exception and validation messages instead of only "The command did not succeed." (Guarded action ignores CommandOutcome.exceptionMessages and shows a generic failure #275)

[woksin]

Reviewer notes

• Change: CoreGuardedAction reads CommandOutcome.exceptionMessages and validationErrors and combines them into the thrown error (trimmed, blank entries dropped, newline-joined). The generic text remains the fallback. Dispatchers stay outcome-based.

• Specs: for_CoreGuardedAction/when_running_a_guarded_command.tsx adds cases for exception messages, validation messages, both together, and the empty fallback. They failed before the fix and pass after it.

• Local: scene.react tests, lint:ci and build pass. In the full yarn ci, one untouched spec failed: primereact/for_editor/when_sanitizing_hostile_html (the 5000-deep nesting case took 6.8 s against the 5 s test timeout, with machine load around 60). It is in a workspace this PR does not touch, and it passed in CI on the same tree (run 40890014802). CI is the authority here.

• Advisory from review, not changed: ActionStatus may show the joined messages on one line. A follow-up can render line breaks if needed.

• Downstream: Stage#857 consumes this through a Scene bump.

• Candidate decision: Enforce Screenplay string-only contains semantics in native guard selection #276 (strict Contains, branch scene-276-strict-contains, built on this commit) is not part of this PR. Its implementation and Stage local-package proof are still hours away, and Stage#857 is waiting on this fix. Enforce Screenplay string-only contains semantics in native guard selection #276 follows in a separate minor PR after this merges.