Media Factory Recipes and Deterministic Transforms

1. A stable preset name is not a stable recipe

A label such as web-final is only a label. If the input, tool build, encoder, parameter set, or metadata changes, the label cannot prove reproducibility. Every transform in this lesson has an auditable recipe_id and recipe_version.

2. The owned CON-015 boundary

CON-015 owns the recipe and reproducibility evidence. CON-014 owns authoritative asset/source/rights/QC records, CON-016 owns command-level execution, CON-017 owns creative variant lineage, and CON-018/CON-022 own publication gates. This lesson makes only bounded transform claims.

3. Bind the exact input with a digest

A filename, path, or thumbnail is not byte identity. The recipe records both input_asset_ref and input_digest. If the digest changes, the next derivative has new lineage; overwriting the old derivative destroys auditability.

4. Treat tool build and environment as recipe inputs

Record tool_id, tool_version, a container image or an environment fingerprint. Identical command text can behave differently across builds or hardware paths, so that change must be typed instead of hidden behind the same preset name.

5. Operation sequence is ordered

Resize-then-crop is not the same recipe as crop-then-resize. Operations and parameters must be ordered and explicit. A changed parameter either requires a new recipe version or must be rejected as recipe drift.

6. Randomness needs a declared policy

If a transform includes seeds, sampling, or behavior that can vary, seed_or_randomness_policy must be NONE, FIXED, or explicitly UNDECLARED. An unknown randomness state cannot support a determinism claim.

7. Metadata and clocks can change bytes

Creation time, encoder tags, or other volatile metadata can alter an output digest even when the media is technically similar. The recipe must say whether such fields are stripped, fixed, or explicitly excluded by a bounded equivalence policy.

8. Define the output spec before execution

Dimensions, container, codec family, sample rate, and other required properties belong in output_spec before the run. The observed output is compared with that contract afterward; “the file plays” is not sufficient evidence.

9. Byte determinism is an evidence claim

Only repeated runs with identical bindings and controlled policies can justify byte_deterministic=true when the output digests match. A repeated command or use of -bitexact alone is not the complete evidence package.

10. Bounded equivalence is different from byte identity

Two byte-different outputs can still satisfy an explicitly defined technical/semantic equivalence policy. The correct decision is then BOUNDED_EQUIVALENCE_ONLY; it must never be relabeled as byte determinism.

11. Link derivation to the run

Every immutable derivative links to the input entity, recipe version, and reproducibility_run_id. PROV can represent entity/activity lineage, while determinism remains a claim proven by the recipe/run evidence.

12. Type the drift

Use states such as INPUT_DRIFT, TOOL_DRIFT, ENVIRONMENT_DRIFT, RECIPE_DRIFT, RANDOMNESS_UNBOUND, and METADATA_TIME_DRIFT. Typed failures are actionable; one vague PASS/FAIL flag is not enough for a media factory.

13. Evidence matrix: declared versus observed

For every run, compare declared and observed input digest, tool/environment, operations/parameters, randomness, metadata policy, output digest, and equivalence result. The typed decision must come from these rows.

14. Lab: eight fixtures and 64 assertions

The synthetic lab includes a byte-identical baseline, parameter drift without a version bump, a new tool/hardware path, timestamp metadata, a changed input digest, unknown randomness, bounded equivalence, and a versioned transfer. The evaluator checks eight outputs per case.

15. Transfer: new digest, new build, new timestamp

The transfer changes an input digest, pins a new tool build, and introduces a timestamp field. Rebuild the recipe evidence to show which changes require a new recipe version, which support only bounded equivalence, and where the decision must be BLOCK or DEFER. The previous result is never the decision authority for the new context.