Add one-shot automatic switch

[bjspi]

Closes #147

Adds codex-auth switch --auto for one-shot automatic switching.

Behavior:

• requires both 5h and weekly remaining limits to be greater than 0%
• skips the currently active account
• chooses the inactive eligible account with the earliest 5h reset window
• supports --api and --skip-api
• rejects --auto with --live or explicit switch targets

Verification:

• Build passed.
• switch --help shows the new --auto usage.
• Full test suite: 408/414 passed, 5 skipped, 1 failed. The remaining failure is the existing Windows PowerShell-only login launcher integration scenario, unrelated to this switch change.

[bjspi]

I need it to automate switching completely without always "knowing" the exact account which has still free limits left... Hope you'll be able to merge it. thanks

[greptile-apps]

Greptile Summary

This PR adds codex-auth switch --auto, a one-shot non-interactive mode that picks the best eligible inactive account (both 5h and weekly limits > 0%) and switches to it without opening the picker. It also fixes a pre-existing tiebreaker bug in the live auto-switch picker where the account with the shortest weekly runway was incorrectly preferred over the one with the most remaining capacity.

• New --auto flag: parsed in switch.zig, dispatches to handleSwitchAuto which reuses the same load/activate/save/print pipeline as the query path; correctly rejected in combination with --live or any explicit target.
• Candidate selection (account_ops.zig): conservative eligibility (unknown usage → ineligible), tiebreaks on earliest 5h reset then longest weekly runway; accounts with API refresh errors are excluded via usage_overrides.
• Tiebreaker bugfix (picker_auto.zig): candidate_weekly_reset < best_weekly_reset → > best_weekly_reset, making the live picker consistent with the new --auto path; covered by a new unit test.

Confidence Score: 5/5

Safe to merge — the new auto-switch path is additive, well-tested, and the tiebreaker fix in the live picker is straightforward and verified by a new unit test.

All changed code paths are exercised by new unit, behavior, and integration tests. The core activate/save/print pipeline is the same pattern already used by the query path. The tiebreaker fix in picker_auto.zig is a one-line correction from < to > with a dedicated test confirming the new behaviour. No existing functionality is altered beyond the error message string that now includes --auto.

No files require special attention. The minor eligibility asymmetry between picker_auto.zig and account_ops.zig (unknown usage treated differently) is worth confirming is intentional but does not affect correctness.

Important Files Changed

Filename	Overview
src/cli/picker_auto.zig	Fixes the pre-existing tiebreaker regression: weekly-reset comparison changed from < to > so the account with the longer weekly runway wins ties. Now consistent with the new autoSwitchAccountIsBetter in account_ops.
src/registry/account_ops.zig	Adds selectAutoSwitchAccountIndexByLimits* family; eligibility conservatively requires both 5h and weekly remaining > 0 (unknown usage → ineligible). Tiebreaker prefers earliest 5h reset, then longest weekly runway.
src/workflows/switch.zig	Adds handleSwitchAuto; correctly dispatches after .previous/.query early-returns; shares the same load/activate/save/print pattern as the query path. refresh_error_name is freed but not surfaced to the user.
src/cli/commands/switch.zig	Parser correctly handles all invalid --auto combinations: duplicate flag, --auto --live, and --auto with any explicit target (query or -). No allocation leaks in error paths.
tests/cli_integration_test.zig	Adds a full integration scenario for switch --auto --skip-api with an eligible backup account; validates auth.json is overwritten, registry active key is updated, and previous key is recorded.
tests/workflows_core_test.zig	Adds two unit tests covering candidate selection: exhausted-5h exclusion, weekly-exhausted exclusion, and the tiebreaker for accounts whose 5h windows have already reset.
src/cli/types.zig	Adds auto: bool = false field to SwitchOptions. Minimal, correct change.
src/cli/output.zig	Adds printNoAutoSwitchCandidateError; follows existing stderr/color conventions and includes a useful hint to run list --api.
src/workflows/preflight.zig	Registers error.NoAutoSwitchCandidate as a handled CLI error so the process exits cleanly without a stack trace.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[codex-auth switch --auto] --> B{Parse flags}
    B -- "--auto + --live" --> E1[UsageError: cannot combine]
    B -- "--auto + query/dash" --> E2[UsageError: does not support --auto]
    B -- valid --> C{api_mode?}
    C -- skip_api --> D1[loadStoredSwitchSelectionDisplay]
    C -- default/force_api --> D2[loadSwitchSelectionDisplay foreground API refresh]
    D1 --> F[selectAutoSwitchAccountIndexByLimitsWithUsageOverrides]
    D2 --> F
    F -- skip active account --> G{eligible accounts?}
    G -- account has usage override/error --> H[skip]
    G -- rem_5h == 0 or rem_week == 0 --> H
    G -- both > 0 --> I[compare: earliest 5h reset tiebreak: longest weekly runway]
    I --> J{any candidate found?}
    J -- no --> E3[printNoAutoSwitchCandidateError error.NoAutoSwitchCandidate]
    J -- yes --> K[activateAccountByKey]
    K --> L[saveRegistry]
    L --> M[printSwitchedAccount]
    M --> N[exit 0]

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%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
    A[codex-auth switch --auto] --> B{Parse flags}
    B -- "--auto + --live" --> E1[UsageError: cannot combine]
    B -- "--auto + query/dash" --> E2[UsageError: does not support --auto]
    B -- valid --> C{api_mode?}
    C -- skip_api --> D1[loadStoredSwitchSelectionDisplay]
    C -- default/force_api --> D2[loadSwitchSelectionDisplay foreground API refresh]
    D1 --> F[selectAutoSwitchAccountIndexByLimitsWithUsageOverrides]
    D2 --> F
    F -- skip active account --> G{eligible accounts?}
    G -- account has usage override/error --> H[skip]
    G -- rem_5h == 0 or rem_week == 0 --> H
    G -- both > 0 --> I[compare: earliest 5h reset tiebreak: longest weekly runway]
    I --> J{any candidate found?}
    J -- no --> E3[printNoAutoSwitchCandidateError error.NoAutoSwitchCandidate]
    J -- yes --> K[activateAccountByKey]
    K --> L[saveRegistry]
    L --> M[printSwitchedAccount]
    M --> N[exit 0]

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_{Reviews (2): Last reviewed commit: "fix(auto-switch): prefer longer weekly r..." | Re-trigger Greptile}