[Justin Chu (justinchuby)]

Reject attribute references in literal constraints without preventing variable-bound references from passing through replacements. Guard CastIdentity, Flatten2Reshape, and ReshapeReshape before reading unresolved attributes.

Regressions reproduce list-valued constraint crashes, erroneous Cast elimination with unknown input dtype, Flatten's axis crash, and unsafe Reshape replacement construction. They also cover multi-output candidate retries, reference-preserving rewrites, and successful/failed/successful reuse of the stateful Reshape rule.

Relates to #1442, #1563, and #2526. Literal multi-output constraint coverage also exists in #3168; no managed-cache framework is introduced.

Validation: 417 tests and 60 subtests passed; one existing skip. lintrunner -a clean.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.85%. Comparing base (f51083c) to head (a65e473).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3191      +/-   ##
==========================================
+ Coverage   73.77%   73.85%   +0.07%     
==========================================
  Files         270      270              
  Lines       33876    33967      +91     
  Branches     3243     3251       +8     
==========================================
+ Hits        24993    25086      +93     
+ Misses       7829     7827       -2     
  Partials     1054     1054              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.