test: cover chooseAccount selection tiers and cursor discipline

[ndycode]

Summary

Tenth suite in the direct-coverage wave (siblings: #559–#561, #563–#567, #569; all independent, based on main). lib/runtime/rotation-account-selection.ts is the phase-2-extracted rotation selector at the heart of the proxy hot path. The proxy giant suite exercises it indirectly; this adds test/rotation-account-selection.test.ts (13 tests) pinning its documented selection contracts directly.

The suite drives a real AccountManager built from V3 storage fixtures — markSwitched, the skip-reason taxonomy, and the cursor bookkeeping are all live. Only the hybrid/sequential selector methods are stubbed per test (via vi.spyOn on the real instance) for deterministic path control, and module-level circuit/rate trackers are reset per test.

What the tests pin

Pinned selection (issue #474):

• The pin wins without any cursor commit — the proxy must not clobber the pin set by the CLI.
• A pin never falls back to another account: already-attempted, missing, policy-blocked, disabled, and rate-limited pins each return null with the precise skip reason recorded.

Session affinity tier:

• The remembered account wins and commits the cursor with markSwitched(account, "rotation", family).
• An unusable sticky account records its runtime skip reason and falls through to the hybrid tier.

Hybrid tier and linear fallback:

• The hybrid selector's pick is returned without an extra cursor commit (it advances its own cursor internally).
• An attempted/blocked hybrid pick falls back to the linear scan, which records a reason per rejected candidate (already-attempted, policy-blocked) and commits the winner as the new cursor.
• An exhausted pool returns null with a reason recorded for every account.

Sequential / drain-first mode (issue #509):

• The drain-first selector governs and the per-session affinity tier is never consulted.
• A transient failure on the active account retries another account without moving the drain-first primary — markSwitched is not called on the within-request fallback, so only true exhaustion advances the pointer.

Validation

• vitest run test/rotation-account-selection.test.ts — 13/13 passing
• npm run typecheck — clean
• npx eslint test/rotation-account-selection.test.ts --max-warnings=0 — clean

https://claude.ai/code/session_01XNtnkLbBiXZxfQQYLMpucB

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Generated by Claude Code

note: greptile review for oc-chatgpt-multi-auth. cite files like lib/foo.ts:123. confirm regression tests + windows concurrency/token redaction coverage.

Greptile Summary

adds test/rotation-account-selection.test.ts — 13 direct-coverage tests for chooseAccount in lib/runtime/rotation-account-selection.ts, driving a live AccountManager built from v3 fixtures with per-test volatile state resets. both issues flagged in previous review threads (missing cooling-down/circuit-open pin coverage and the sequential policy-blocked primary path) are addressed.

• pin tier now covers all six skip reasons (already-attempted, missing, policy-blocked, disabled, rate-limited, cooling-down:*, circuit-open) and asserts cursor is not committed.
• affinity tier verifies cursor commit on hit and reason recording on fallthrough; hybrid tier asserts no extra cursor commit; sequential tier pins drain-first stickiness, policy-blocked routing, and within-request retry without moving the active pointer.

Confidence Score: 5/5

test-only addition with no production code changes; the live AccountManager and module-level state reset in beforeEach are correct and all 13 contracts align with the implementation.

the suite correctly drives the real AccountManager, resets volatile circuit/rate state per test, and properly stubs only the hybrid/sequential selector methods — the selection contracts asserted match the chooseAccount implementation exactly. all findings are coverage gaps, not defects in the tests or the code they exercise.

no files require special attention

Important Files Changed

Filename	Overview
test/rotation-account-selection.test.ts	new 13-test suite directly pinning chooseAccount contracts across pin, affinity, hybrid, and sequential tiers using a live AccountManager; addresses all previously flagged coverage gaps except workspace-disabled

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[chooseAccount] --> B{pinnedIndex?}
    B -- yes --> C{attempted / missing / blocked?}
    C -- yes --> D[record skip reason]
    C -- no --> E{enabled? runtime skip?}
    E -- no --> D
    E -- yes --> F[return pinned no markSwitched]
    B -- no --> G{schedulingStrategy = sequential?}
    G -- yes --> H[getCurrentOrNextForFamilySequential]
    H --> I{usable and not attempted/blocked?}
    I -- yes --> J[return selected no markSwitched]
    I -- no --> K[chooseLinearScanFallback advancePtr=false]
    K --> L[return winner no markSwitched]
    G -- no --> M{session affinity hit?}
    M -- yes --> N{usable?}
    N -- yes --> O[markSwitched then return preferred]
    N -- no --> P[record skip reason then fall through]
    M -- no --> Q[getCurrentOrNextForFamilyHybrid]
    P --> Q
    Q --> R{usable and not attempted/blocked?}
    R -- yes --> S[return hybrid pick no markSwitched]
    R -- no --> T[chooseLinearScanFallback advancePtr=true]
    T --> U[markSwitched then return winner]
    T -- exhausted --> V[null]

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Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 1
test/rotation-account-selection.test.ts:87-101
**`workspace-disabled` skip reason not covered in any tier**

`getAccountRuntimeSkipReason` can return `"workspace-disabled"` when `hasEnabledWorkspaces` is false. this PR closed the `cooling-down` and `circuit-open` gaps, but `workspace-disabled` is the last untested branch in the same function. a pin, affinity sticky hit, or sequential primary that has all workspaces disabled would silently return `null` without the skip reason contract being pinned. to exercise it, add workspace metadata to a fixture account via the existing `overridesByIndex` mechanism (e.g. `workspaces: [{ enabled: false }]`) and assert the recorded reason is `"workspace-disabled"` — at minimum in the pin tier, which already has dedicated cases for every other reason.

_{Reviews (2): Last reviewed commit: "test: cover cooling-down and circuit-ope..." | Re-trigger Greptile}

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 9e4b3a31-6a2e-4e8e-8dcc-f769ff52183e

📥 Commits

Reviewing files that changed from the base of the PR and between b566656 and 7d946f9.

📒 Files selected for processing (1)

• test/rotation-account-selection.test.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/audit-51-rotation-selection-tests

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/audit-51-rotation-selection-tests

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