refactor(common): extract ApiError::status_code helper

[geoffjay]

refactor(common): extract ApiError::status_code helper

refactor(common): extract ApiError::status_code helper from into_response (closes #720)

[geoffjay]

This change is part of the following stack:

• refactor(common): extract ApiError::status_code helper #739 ◀

_{Change managed by git-spice.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.69%. Comparing base (a5867f0) to head (8a5acd4).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #739      +/-   ##
==========================================
+ Coverage   55.66%   55.69%   +0.02%     
==========================================
  Files         126      126              
  Lines       13759    13763       +4     
==========================================
+ Hits         7659     7665       +6     
+ Misses       6100     6098       -2     

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[geoffjay]

👀 Conductor: Awaiting Reviewer

PR #739 (refactor(common): extract ApiError::status_code helper) has CI passing and is in the review-agent queue awaiting a reviewer pickup.

Nudge posted by conductor pipeline sync.

[geoffjay]

Review: refactor(common): extract ApiError::status_code helper

Stack position: issue-720 is directly on main with no parent PR
dependency, but git-spice reports (needs restack) — the branch is behind
main and must be rebased before the conductor can merge it.

---

Code quality: approved

The change is correct, focused, and well-tested. Specific notes:

status_code() method — the variant→status mapping is identical to the
old per-arm match in into_response. No behaviour change.

Internal case — the old code used e.to_string() (on the inner
anyhow::Error); the new code uses self.to_string(). Because Internal is
annotated #[error(transparent)], Display delegates to the inner error, so
the two produce identical strings. Correct.

into_response simplification — going from 7 match arms (each repeating
self.to_string()) to two lines is the right outcome. The match &self /
self.to_string() awkwardness (matching a reference to get the status then
calling to_string on the owner) is gone.

Tests — 7 tests, one per variant, all exercising status_code() directly.
anyhow::anyhow!("boom").into() for Internal is the idiomatic pattern.
Coverage is complete.

Scope — single file, single responsibility, no unrelated changes.

---

Action required before merge

Rebase onto main:

git-spice branch restack
git-spice branch submit

Once restacked, add merge-queue to trigger the conductor.