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phases/1-core-runtime-contracts/step3.md

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+# Step 3: runtime-cache-policy
+
+## Read First
+- /AGENTS.md
+- /PLAN.md
+- /PROGRESS.md
+- /docs/HARNESS.md
+- /docs/IMPLEMENTATION_PLAN.md
+- /docs/TOOLCHAIN.md
+- /docs/CONVERSION_POLICY.md
+- /phases/1-core-runtime-contracts/step1.md
+- /phases/1-core-runtime-contracts/step2.md
+
+## Task
+Establish model cache, log path, and resume state policy as typed contracts and documented path helpers.
+
+The result should prepare later CLI/runtime phases to use local model cache paths and offline-preferred model loading.
+
+## Sprint Contract
+- Done means: model cache and runtime cache path contracts are tested and documented without downloading models.
+- Hard thresholds: no network download is triggered; logs/state remain outside generated Markdown content; environment variable overrides are deterministic.
+- Files owned: `src/pdftomd/`, `tests/`, `docs/TOOLCHAIN.md`, `PROGRESS.md`, `phases/1-core-runtime-contracts/index.json`.
+- Dependencies: Steps 1 and 2.
+
+## Acceptance Criteria
+```powershell
+python scripts\validate_workspace.py
+.\venv\python.exe -m pytest tests
+```
+
+## Verification
+1. Run the acceptance commands.
+2. Confirm `docs/TOOLCHAIN.md` stays consistent with any cache path decisions.
+3. Update `PROGRESS.md` and this phase index.
+
+## Do Not
+- Do not download Marker or Nougat weights.
+- Do not add hosted storage or cloud cache behavior.
+- Do not write warnings into Markdown output.