ZCode UI 'Delete Provider' operation is incomplete — provider definitions remain in v2/config.json after deletion, causing model selection to fail

Bug Report: ZCode UI "Delete Provider" Operation Causes Model Selection Failure

Title: ZCode UI "Delete Provider" is incomplete — provider definitions remain in v2/config.json after deletion, causing model selection to fail

• Type: Bug
• Priority: P2
• Status: Needs triage

Environment

• OS: Windows 10 (win32 10.0.26200 x64)
• ZCode Version: Not confirmed (desktop app)
• Model channel: Mixed (Infron/motif-3, Agnes, kilo, NVIDIA, AMD, etc.)
• Workspace: C:\Users\木\Desktop\talk

Problem

When using the ZCode desktop UI to delete providers (leaving only Infron/motif-3), the operation only updates v2/provider_config.json (the providerOrder array) but does NOT remove the corresponding provider definitions from v2/config.json. This causes an internal state inconsistency where:

• v2/provider_config.json says "only Infron is active"
• v2/config.json still contains all 12 provider definitions (Agnes, NVIDIA, kilo, VyceAI, OpenCode, AMD, plus 6 built-in)
• The zcode-provider extension merges these into the app-server settings file (cli/config.json)
• When a user tries to re-select a "deleted" provider, the UI allows it (because the definition still exists in v2/config.json), but the selection fails because the provider is absent from providerOrder

Steps to Reproduce

1. Open ZCode desktop application
2. Go to Settings → Model Management
3. Select and delete all providers except Infron (motif/motif-3)
4. Attempt to re-select one of the "deleted" providers (e.g., Agnes, kilo, NVIDIA)
5. Observe that the model selection does not take effect

Expected vs Actual Behavior

• Expected: After deleting a provider, it should not appear in the model selector, and attempting to re-select it should either work correctly or be clearly unavailable
• Actual: The provider can still be selected (because its definition persists in v2/config.json), but the selection fails silently. Switching between any providers produces the same failure

Root Cause Analysis

1. Incomplete deletion: UI "delete provider" only modifies v2/provider_config.json (providerOrder) but does not clean up v2/config.json
2. State inconsistency: Two files that should always agree now disagree — one has order-only info, the other has full provider definitions
3. Merge behavior: The zcode-provider extension merges enabled providers from v2/config.json into cli/config.json (app-server settings), but does not account for providerOrder when determining which providers are "active"

Logs (for reference)

• Log file: C:\Users\木\.zcode\cli\log\zcode-2026-09-17.jsonl
• Key errors observed:
  • v4 createSession config apply failed: provider "601113d1" is not in the workspace model registry
  • session.model_selection.persist_failed: FOREIGN KEY constraint failed
  • Multiple model.sdk.stream.failed events (network/TLS disconnections)

Suggested Fix

1. UI level: When the user deletes a provider, also remove the corresponding entry from v2/config.json (or mark it with enabled: false)
2. Extension level: The zcode-provider merge logic should consider providerOrder when determining which providers to merge — if a provider is not in providerOrder, it should not be considered "active"
3. Consistency check: Add a validation that providerOrder keys are a subset of v2/config.json provider keys

Additional Notes

This issue appears to be part of a larger problem with the current configuration state:

• 4 ghost sessions exist in the database with no corresponding session rows (causing FOREIGN KEY constraint failures)
• Clash Verge proxy is causing TLS disconnections for some providers
• Self-hosted Qwen3.8 does not accept reasoning effort: high (only xhigh/medium/low)

These may be separate issues but contribute to the overall "model selection fails" symptom.

Logs & Attachments

• Log archive: C:\Users\木\.zcode\cli\log\zcode-2026-09-17.jsonl (available on request)
• Configuration files: v2/config.json, v2/provider_config.json, cli/config.json

Trace the delete-provider flow from the desktop UI through v2/provider_config.json, v2/config.json, and the zcode-provider merge into cli/config.json. Confirm how providerOrder and provider definitions are read, then add coverage for deleting a provider and attempting to select it. Done means deleted providers are unavailable and the configuration files remain consistent.