| name | add-torch-shapes-example |
| description | Use when adding a new PyTorch model to Pyrefly's shape-tracking example corpus under tensor-shapes/pyrefly-torch-stubs/examples — i.e. importing a model as a tested, corpus-quality reference port. This is maintainer-facing fbsource work. For porting your own model elsewhere, use the porting skill directly; for fixing a wrong/missing shape rule, use modify-shaped-array-dsl. |
You are importing a PyTorch model into Pyrefly's example corpus at
tensor-shapes/pyrefly-torch-stubs/examples/. This is the contribution case the porting
skill describes: these ports are tested reference material that others read to
learn the patterns, so produce its fuller deliverable — paste every artifact
(audit table, per-local reveal_type dumps, typed-interface receipts, exhaustive
assert_type coverage, completion report) in full, not just the annotated model.
Why these ports matter. They demonstrate what happens when you write a real
PyTorch model with tensor shape types, proving real-world utility. If you exclude
features or simplify the model, you prove nothing — the hard parts are exactly
where the value needs to be demonstrated. So port the model faithfully and in
full (see step 2).
Improving the stubs is the point, not a side quest. In the general porting
skill, changing stubs is optional and a missing shape can just be documented as a
gap. Here it is the opposite: a corpus example exists to exercise and harden the
stubs. When an op falls back to bare Tensor, treat it as a stub deficiency to
fix, not a gap to record — refine the stub signature (or add a shape DSL rule) so
the shape is recovered, then make that the general truth about the op, not a
special case for this model. A port that leaves easily-fixable bare Tensors
behind is not done. Only genuinely data-dependent shapes (e.g. data-dependent
token counts) should remain bare, with a comment saying why.
1. Run the port
Do the actual porting by reading and following the add-shape-types-to-torch-model
skill's SKILL.md (in tensor-shapes/skills/add-shape-types-to-torch-model/) end to
end — its gated workflow (pre-flight gates → per-module loop → verification) is the
algorithm.
That skill opens with two questions for the user; for corpus work you already have
the answers, so don't stop to ask: the check command is the buck invocation in
step 3 below, and stub changes are in scope (corpus ports should track shapes as
fully as possible, so refine stub signatures when that recovers real shapes).
Produce all of its output artifacts; for the corpus they are required.
2. Place the file
Write the port at tensor-shapes/pyrefly-torch-stubs/examples/<model>.py. Every class,
function, and method from the original belongs in the port — the corpus values
completeness.
3. Verify (the fbsource commands)
The porting skill's verification phase tells you to run verify_port.sh and then "the
actual Pyrefly check." In fbsource that check is a buck invocation against the
shape-aware stubs:
buck build fbcode//pyrefly/tensor-shapes:torch-stubs-search-path
buck run fbcode//pyrefly:pyrefly -- check --config /dev/null --python-version 3.13 --tensor-shapes true --search-path "$(buck targets --show-output fbcode//pyrefly/tensor-shapes:torch-stubs-search-path | awk '{print $2}')" tensor-shapes/pyrefly-torch-stubs/examples/<model>.py
The result must be 0 errors, with no leftover reveal_type.
Then run the corpus test target so the new example is covered by CI:
buck test fbcode//pyrefly/tensor-shapes/pyrefly-torch-stubs/examples:torch_examples_test
If you hit a wrong or missing shape
A missing shape (op falls back to bare Tensor) is usually a loose or absent
stub signature — fix it in the stubs so the shape is recovered (see "Improving
the stubs is the point" above), rather than documenting it as a gap.
A wrong shape (Pyrefly computes a concrete shape that's incorrect) or a missing
shape that can't be expressed by a stub signature alone is a shape-DSL change: see
the modify-shaped-array-dsl skill. That skill insists on unit-testing the DSL
logic, not just relying on this example to exercise it. Don't reach for the DSL
for shapes a stub signature could express.
