fix(wren): make resolve_model_name's case-insensitive fallback deterministic

[AmirF194]

Summary

resolve_model_name's unquoted case-insensitive fallback returns whichever
candidate the input set happens to iterate first when two model names
differ only in case. For a set of strings that order depends on string
hashing, which is randomized per process (PYTHONHASHSEED), so an identical
query can bind a different model across restarts of the same server. This
tracks the lexicographically smallest match in the same single pass instead,
so the result no longer depends on the interpreter's hash seed.

What failure does this repair?

from wren.policy import resolve_model_name
resolve_model_name("ORDERS", False, {"Orders", "orders"})

Running that same line in 8 fresh subprocesses on current main:

['Orders', 'orders', 'orders', 'orders', 'Orders', 'Orders', 'orders', 'orders']

Same input, same manifest, different answer per process: 5 runs resolved to
orders, 3 resolved to Orders. On this branch all 8 return Orders.

test_case_sensitivity.py already documents this pair as a legitimate manifest
shape, and its own test_resolve_model_name_dual_case accepts either result
for this exact case ("USERS unquoted may pick either manifest entry
depending on set iteration order"). This change does not reverse that: an
ambiguous unquoted reference still resolves to a case-insensitive match, and
that test still passes unmodified. It only removes the "depending on set
iteration order" part, so the same query gives the same answer on every run.

How is it tested?

• test_resolve_model_name_case_collision_is_deterministic (new, in
  tests/unit/test_policy.py) runs the lookup 8 times and asserts the same
  result each time, mirroring the subprocess reproduction above.
• The existing tests/unit/test_policy.py and tests/unit/test_case_sensitivity.py
  suites (107 tests) pass unmodified, including the dual-case tests that
  intentionally keep Users/users as two distinct models.
• ruff format --check src/ and ruff check src/ pass.
• Ran the full tests/unit/ suite (excluding the memory/mcp extras, matching
  CI): 1248 passed, 2 skipped, 3 pre-existing failures in
  test_served_content_guard.py unrelated to this change and present on main
  in the same environment (they need the mcp/ui extras to register every CLI
  subcommand the guard checks against).
• Not benchmarked: the loop this touches was already a full scan of
  model_names per unquoted reference, so this adds one str comparison only
  on the (rare) case-insensitive hit path, no new allocation or second pass.

Duplicate check

competing-prs.sh swept all 72 open PRs; two drafts by the same author
(#2551, #2552) touch this file but only insert an unrelated basic_safety_check
function immediately after resolve_model_name and edit an error message
elsewhere in _check_functions. Neither touches the fallback loop this PR
changes, and no open PR modifies resolve_model_name itself.

Summary by CodeRabbit

• Bug Fixes

  • Table references that match multiple model names differing only by letter case now resolve consistently by selecting the lexicographically smallest match.
  • Exact matches, quoted names, case-insensitive fallback behavior, and unmatched references continue to work as expected.

• Tests

  • Expanded coverage for matching precedence, case sensitivity, missing models, and deterministic results across different runtime environments.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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• core/wren/tests/unit/test_policy.py

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Walkthrough

resolve_model_name now resolves case-insensitive collisions deterministically. Its documentation and unit test define the lexicographically smallest match and verify it across processes with different hash seeds.

Changes

Model name resolution

Layer / File(s)	Summary
Deterministic resolution and validation core/wren/src/wren/policy.py, core/wren/tests/unit/test_policy.py	resolve_model_name now returns the lexicographically smallest case-insensitive match. The test runs isolated subprocesses with eight PYTHONHASHSEED values and asserts that each result is "Orders".

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to efde8

This change makes ambiguous case-insensitive model-name resolution deterministic without changing the accepted matching behavior; no actionable merge-blocking risk remains after normal checks and review.

Poem

A rabbit checks the model names,
With careful paws and tidy frames.
Hash seeds change, results stay bright,
"Orders" appears just right.
Stable paths through code remain.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 42.86% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the primary change: deterministic case-insensitive fallback behavior in resolve_model_name.
Description check	✅ Passed	The description includes all required sections. It provides a concrete reproduction with actual output, explains the repair, lists targeted and broader tests, reports unrelated pre-existing failures, …
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description includes all required sections. It provides a concrete reproduction with actual output, explains the repair, lists targeted and broader tests, reports unrelated pre-existing failures, and documents the duplicate check.

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Actionable comments posted: 1

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Inline comments:
In `@core/wren/tests/unit/test_policy.py`:
- Around line 705-706: Update the determinism test around resolve_model_name to
execute the lookup in fresh subprocesses using multiple PYTHONHASHSEED values,
rather than repeating it in one process. Assert that every subprocess returns
"Orders", preserving the behavior described by the test docstring.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Team

Run ID: 71ac6762-7925-4004-a862-261e35283e57

📥 Commits

Reviewing files that changed from the base of the PR and between 992f1da and 7f5203b.

📒 Files selected for processing (2)

• core/wren/src/wren/policy.py
• core/wren/tests/unit/test_policy.py

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.

[AmirF194]

Good catch, the loop was proving the wrong thing. Within one process the old buggy code also returns the same answer every time (fixed hash seed, stable iteration order), so it would have passed on unfixed code too. Pushed a version that spawns a fresh subprocess per PYTHONHASHSEED instead, which fails on the pre-fix code and passes on this one.