Summary

• Problem: When an agent is not explicitly listed in agents.list (relying on agents.defaults), the UI handlers for model and fallback changes returned early, failing to mark the configuration as "dirty."
• Why it matters: Users with minimal or single-agent configurations were forced to use the "Config" tab to persist model changes, as the Agents overview UI was effectively read-only for the default agent.
• What changed: Updated onModelChange and onModelFallbacksChange in app-render.ts to correctly target agents.defaults.model when the default agent is edited. The fix also ensures that updates to defaults are always wrapped in a { primary: ... } object to comply with the stricter Zod schema for AgentDefaults.
• What did NOT change (scope boundary): Handlers for Tools and Skills were not changed because agents.defaults does not support these field overrides; they still require an explicit entry in agents.list.

Change Type (select all)

• Bug fix
• Feature
• Refactor
• Docs
• Security hardening
• Chore/infra

Scope (select all touched areas)

• Gateway / orchestration
• Skills / tool execution
• Auth / tokens
• Memory / storage
• Integrations
• API / contracts
• UI / DX
• CI/CD / infra

Linked Issue/PR

• Closes [Bug]: /agents Save button stays disabled when only default agent exists (no agents.list) #20924

User-visible / Behavior Changes

Users can now edit the Primary model and Fallbacks for the default agent in the /agents sidebar and successfully save those changes to their configuration.

Security Impact (required)

• New permissions/capabilities? (No)
• Secrets/tokens handling changed? (No)
• New/changed network calls? (No)
• Command/tool execution surface changed? (No)
• Data access scope changed? (No)

Repro + Verification

Environment

• OS: Linux (WSL2) / Windows
• Runtime/container: Native Node.js
• Model/provider: Any
• Integration/channel (if any): N/A
• Relevant config: agents.defaults populated, agents.list empty.

Steps

1. Navigate to /agents in the Control UI.
2. Select the default/main agent from the sidebar.
3. In the Overview panel, change the value of "Primary model (default)" or edit "Fallbacks".
4. Observe the "Save" button.

Expected

• The "Save" button should become enabled immediately.
• Clicking "Save" should persist the change to agents.defaults.model in the configuration file.

Actual

• Before this fix, the "Save" button remained disabled and changes were lost on page refresh.

Evidence

Verified via code audit that the update correctly targets agents.defaults.model as an object { primary: modelId } to satisfy AgentDefaultsSchema (found in src/config/zod-schema.agent-defaults.ts).

Human Verification (required)

• Verified scenarios: Editing both Primary Model and Fallbacks individually and together for the default agent.
• Edge cases checked: Verified that if the agent is in agents.list, the handler still correctly targets the specific list entry index instead of defaults.
• What you did not verify: I did not verify automatic persistence on mobile/TUI environments, as this is a dashboard-specific fix.

Compatibility / Migration

• Backward compatible? (Yes)
• Config/env changes? (No)
• Migration needed? (No)

Failure Recovery (if this breaks)

• How to disable/revert this change quickly: Revert the changes to ui/src/ui/app-render.ts
• Files/config to restore: None.
• Known bad symptoms reviewers should watch for: If the object wrapping logic were missing, the backend would reject the save with a Zod validation error.

Risks and Mitigations

• Risk: Potential invalid configuration if the target path for agents.defaults didn't exist in the form state.
• Mitigation: The code includes checks for configValue and agentsList.defaultId existence before attempting the update.

Greptile Summary

Fixed Save button in /agents UI for default agent model changes. Previously, editing the primary model or fallbacks for the default agent (when not explicitly listed in agents.list) would return early without marking the configuration as dirty, leaving the Save button disabled. The handlers now check if the agent matches state.agentsList?.defaultId and correctly target agents.defaults.model with proper object wrapping ({ primary: modelId }) to comply with the AgentDefaults Zod schema.

• Both onModelChange and onModelFallbacksChange handlers now support default agent editing
• Wraps model values in { primary, fallbacks? } object when updating defaults
• Preserves existing behavior for agents explicitly listed in agents.list

Confidence Score: 4/5

• Safe to merge with minor consideration for edge case verification
• The fix correctly addresses the described problem by adding fallback logic to target agents.defaults.model when the agent isn't in the list. The object wrapping logic properly aligns with the strict Zod schema requirements. However, there's a minor edge case: the code assumes state.agentsList?.defaultId exists when falling through to the default path - if defaultId is undefined, the code would still return early, which is correct. The fix is well-structured and maintains backward compatibility.
• No files require special attention

_{Last reviewed commit: 1488ddf}