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phases/2-marker-adapter/step3.md

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+# Step 3: marker-failure-reporting
+
+## Read First
+- /AGENTS.md
+- /PLAN.md
+- /PROGRESS.md
+- /docs/HARNESS.md
+- /docs/IMPLEMENTATION_PLAN.md
+- /docs/CONVERSION_POLICY.md
+- /phases/2-marker-adapter/step0.md
+- /phases/2-marker-adapter/step2.md
+
+## Task
+Define structured Marker failure reporting for parser errors, unsupported pages, timeout-like failures, and recoverable partial output.
+
+This prepares later CLI and resume behavior without writing CLI code.
+
+## Sprint Contract
+- Done means: Marker adapter failures are typed, testable, and do not corrupt generated Markdown content.
+- Hard thresholds: failures include page/chunk context where available; errors go to runtime reporting paths, not document body; fallback eligibility is explicit.
+- Files owned: `src/pdftomd/marker_adapter.py`, error/reporting models, tests, `PROGRESS.md`, phase index.
+- Dependencies: Steps 0 and 2.
+
+## Acceptance Criteria
+```powershell
+python scripts\validate_workspace.py
+.\venv\python.exe -m pytest tests
+```
+
+## Verification
+1. Run the acceptance commands.
+2. Confirm failure messages are actionable for CLI and evaluator use.
+3. Update `PROGRESS.md` and this phase index.
+
+## Do Not
+- Do not silently swallow Marker failures.
+- Do not implement resume state here.
+- Do not write errors into Markdown chunks.