[madsiberian]

Problem

Two independent bugs kept the v2 fallback from working for Z.AI coding-plan users on Windows:

1. Config never found on Windows. loadConfig used process.env.HOME || "". On Windows HOME is normally unset, so the home-based search paths resolved against the process cwd instead of the user profile. The plugin silently found no config, fallbackModels stayed empty, and setup registered nothing.

2. Variant models never matched the chain. sameModel compared the reasoning-effort variant, so a session on glm-5.3#high (configured via reasoningEffort: "high") never matched a variant-less chain entry. The retry hook fired and detection passed (HTTP 429), but handles(model) returned false, so no fallback ever engaged.

Changes

• src/utils/config.ts: fall back to os.homedir() when HOME is unset.
• v2.ts: ignore the variant when matching (sameModel), and carry the failed model's variant onto same-model fallbacks (chainFor) so glm-5.3#high -> zai/glm-5.3#high preserves effort; different-model tiers (e.g. a flash model) keep their default effort.

Testing

• Added a config test asserting loadConfig falls back to os.homedir() when HOME/XDG_CONFIG_HOME are unset.
• Added two v2 tests: the variant is carried onto the same-model fallback, and not carried onto a different-model fallback.
• vitest run: 734 passed (the 2 failures are pre-existing symlinkSync EPERM tests that need admin/Developer Mode on Windows — unrelated).
• npm run typecheck and npm run build pass.
• Version bumped 2.1.0 -> 2.1.1 per AGENTS.md.

Note

errorPatterns.custom is parsed by validateConfig but never wired into the v2 detection path (the v2 entrypoint matches against a fixed pattern list). That's a separate gap left untouched here; flagging it in case you want a follow-up.