[vincentkoc]

What Problem This Solves

embed reports success for unsupported embedding bases when a repository has no embedding tasks.

User Impact

Unsupported bases now fail with a diagnostic naming the supported choices, even for empty repositories. All three supported bases still allow successful empty runs. Configuration and clustering continue to accept externally supplied vector bases.

Why This Change Was Made

Use the store's existing supported-basis predicate before API-key resolution and task selection, replacing the legacy-only guard and its obsolete diagnostic. Replace the weak legacy-basis assertion with a focused empty-archive regression. Update the changelog and cleanup ledger.

Evidence

• The actual built CLI reproduced false success for two unsupported bases before the fix. It now rejects three unsupported names and succeeds for all three supported empty runs.
• The new regression reproduces the original nil error and checks supported/unsupported outcomes and zero provider requests against temporary SQLite and a loopback provider.
• Focused embedding, configure, refresh, neighbor, fallback, and external-vector clustering race tests passed, along with tidy, formatting, vet, vulnerability, and dead-code checks.
• Independent P0–P3 review found no actionable issues. Full platform CI must pass before landing. No live archives or external provider requests were used.

[clawsweeper]

🦞👀
ClawSweeper picked this up.

Pull request received. I will update this pull request when review starts.