sam2.1-hiera-tiny-mic

Slim model weights, executable usage and framework expectations in one repository.

• Contract manifest
• Transformers usage
• Transformers expectations
• Fixture provenance
• How the fixture was shrunk

Contract

SAM2 Video streaming segmentation

Runnable usage and the framework expectations directory are linked above.

Slim model

Slim fixture: sam2.1-hiera-tiny-mic

A 1.9M-parameter fixture for the Sam2Video MIC, covering facebook/sam2.1-hiera-tiny. It is a test artifact, not a usable model, tagged test-artifact to keep it out of candidate-model search.

• Fixture key b1ade3ded8b7. It covers every checkpoint whose processor files are byte-identical and whose config matches after shrinking.
• Same architecture, smaller config: Sam2Model, shrunk by the generic rule in sweep.py (mask_decoder num_hidden_layers 2).
• Processor files copied byte for byte from facebook/sam2.1-hiera-tiny: preprocessor_config.json, processor_config.json, sam2.1_hiera_t.yaml, video_preprocessor_config.json.
• Overfit to the contract's training step (50 steps). Random weights failed the input-sensitivity gate: pixel_values:reverse moved the logits by only 1.2e-06 (threshold 0.001).
• Same tensor names as the real checkpoint. The real checkpoint has every parameter, and so does the fixture.
• Saved in float32, the dtype facebook/sam2.1-hiera-tiny loads in by default.
• Finite in float32, bfloat16, and float16 (forward, loss, gradients).

Built by build_fixtures.py; build.json records the pinned sources, gate results, and file hashes. This repository includes the slim weights, usage and framework expectations; rebuild the other files with python example/build_fixtures.py --fixture sam2.1-hiera-tiny-mic.