Merge pull request #5917 from deepseek-harness/docs/error-handling-style

docs: define error handling responsibilities and failure guarantees

AGENTS.md

@@ -143,6 +143,7 @@ Real-API tests/demos read `DEEPSEEK_API_KEY`, optional `DEEPSEEK_BASE_URL`, and
 - **No new assertions to `unknown`** (`as unknown` or `<unknown>`). Preserve or reduce the exact legacy baseline; use typed values or validation for replacements ([rule](.agents/notes/implemented/process/2026-09-19-no-unknown-casts.md)).
 - **Source plane vs artifact plane, never mixed.** Static gates and tests resolve workspace imports through tsconfig `paths` to `src` and pass on a clean tree; gates consuming built `lib/` declare that dependency ([layout](docs/development.md#typescript-project-layout)).
 - **Keep compiler faces explicit.** A package with both Host and Client programs exposes face-specific leaf configs and a solution-only root; repo-wide programs seed a face config, never the root solution ([layout](docs/development.md#typescript-project-layout)).
+- **Error handling:** use typed, structured failures and localized, actionable reports. Define handling ownership, containment, and failure guarantees; stop dependent work and visibly report untrusted state or unknown outcomes. Follow [dsh-error-handling](.agents/skills/dsh-error-handling/SKILL.md).
 - **An empty `catch` names the error** and why; keep its `try` to one statement.
 - **Keep comments local.** Do not restate code, expand unrelated comments, or explain distant behavior without local need ([rationale](.agents/skills/dsh-prose-standard/SKILL.md)).
 - **Ban `prove` + `nance`** ([rule](.agents/notes/implemented/process/2026-08-26-ban-ambiguous-origin-label.md)).