Summary

When switching provider via /provider <name> and the [[llm.providers]] entry has no explicit model field, the runtime model name is set to the provider type string (e.g. "ollama", "claude") instead of the actual default model.

Location

crates/zeph-core/src/agent/provider_cmd.rs:120-122

let model_name = entry.model.clone().unwrap_or_else(|| new_provider.name().to_owned());

Impact

• /provider status shows wrong model name
• Cost tracking and tracing spans report incorrect model
• Affects all provider entries without an explicit model field in config

Fix

Use ProviderEntry::effective_model() or the provider type's default model constant instead of new_provider.name() as fallback.

Severity

Medium — incorrect display/tracking, not a crash or data loss.

Discovered during code review of PR #2150.