Closes cumulative review batches 49-51 Finding F1 (Medium /
Maintainability) -- the 7-way duplication of _assert_engine_output_dim
across c2_vpr secondary VPR strategy modules.
Add c2-internal helper assert_engine_output_dim(inference_runtime,
handle, preprocessor, descriptor_dim, *, output_key='embedding',
input_key='input') in src/gps_denied_onboard/components/c2_vpr/
_engine_dim_assertion.py. The helper runs a zero-init dry-run
inference at preprocessor.input_shape() and asserts the engine output
dict carries (1, descriptor_dim) under output_key. Raises
gps_denied_onboard.config.schema.ConfigError on mismatch (preserving
the prior error envelope and message wording byte-identically).
Migrate 7 strategy modules (ultra_vpr, net_vlad, mega_loc, mix_vpr,
sela_vpr, eigen_places, salad) to import the helper and delete the
local _assert_engine_output_dim definitions + their inline
'AZ-527 (planned)' comments. NetVLAD is the only call site that
overrides output_key='vlad_descriptor'; the other 6 explicitly pass
output_key=_OUTPUT_KEY + input_key=_ENGINE_INPUT_KEY (matching helper
defaults but documenting strategy contract at the call site).
Add tests/unit/c2_vpr/test_az527_engine_dim_assertion.py (14 tests,
AAA pattern, Protocol-conforming fakes) covering AC-1..AC-4: helper
signature; wrong shape raises ConfigError naming both dims; missing
output key raises ConfigError naming the missing key; AST-walk
regression guard for stray definitions outside the helper module
(modeled on AZ-526's test_ac4_az526_no_module_level_iso_ts_from_clock_outside_helper);
import-grep regression guard verifying all 7 strategy modules import
the helper.
AC-5 (existing AZ-337/338/339/340 AC-6 sub-tests pass unmodified) is
exercised transitively: c2_vpr/ full directory 230/230 PASS, no test
file modified outside the new test_az527_*. AC-6 (AZ-270 + AZ-507
layer lints) verified by tests/unit/test_az270_compose_root.py
8/8 PASS.
Code-review verdict: PASS (zero findings). Ruff clean.
Co-authored-by: Cursor <cursoragent@cursor.com>
Oleksandr Bezdieniezhnykh