feat(gastown): Per-role model configuration in town settings — mayor, refinery, polecat

[jrf0110]

Summary

Allow users to configure a different model for each agent role (mayor, refinery, polecat) in town settings. Currently there is a single default_model that applies to all agents. Users should be able to, for example, run the mayor on a cheaper/faster model (Sonnet) while running the refinery on a more capable model (Opus) for thorough code review.

Motivation

Different roles have different requirements:

• Mayor: Conversational, needs to be fast and responsive. A lighter model is often fine.
• Refinery: Reviews code quality, correctness, and security. Benefits from the most capable model available.
• Polecat: Implements features and fixes. Benefits from strong coding models, but cost scales with the number of concurrent polecats.

A single default_model forces a trade-off between cost and quality across all roles. Per-role configuration lets users optimize each independently.

Design

Town Config Schema

// townConfig — extend existing config
{
  default_model: string;           // Existing — fallback for any role without a specific model
  role_models?: {                  // New — per-role overrides
    mayor?: string;                // e.g. "anthropic/claude-sonnet-4.6"
    refinery?: string;             // e.g. "anthropic/claude-opus-4.6"  
    polecat?: string;              // e.g. "anthropic/claude-sonnet-4.6"
  };
}

When dispatching an agent, the model is resolved as:

const model = townConfig.role_models?.[agent.role] ?? townConfig.default_model;

This is backward compatible — existing towns without role_models continue using default_model for everything.

Settings UI

In the "Agent Defaults" section of town settings, replace the single model selector with a section showing:

Agent Models

  Default Model     [anthropic/claude-sonnet-4.6  ▾]
  
  Override by role (optional):
  Mayor             [Use default                  ▾]
  Refinery          [anthropic/claude-opus-4.6    ▾]
  Polecat           [Use default                  ▾]

Each role dropdown includes a "Use default" option (which maps to undefined in the config, falling back to default_model). The dropdowns should use the model selector component from #1430 once that ships, or plain text inputs as a stopgap.

Dispatch Changes

buildKiloConfigContent() in container/src/agent-runner.ts currently receives a single model string. Extend StartAgentRequest to include the role-specific model:

interface StartAgentRequest {
  // ... existing fields
  model: string;        // Already resolved per-role by the caller
}

The resolution happens in TownDO before dispatch — scheduling.dispatchAgent or the reconciler's applyAction('dispatch_agent') resolves the model from role_models?.[role] ?? default_model and passes it to the container.

Mayor Model Change

If the mayor's model is changed while it's running, this ties into #1438 (mayor session restart on model change). The same mechanism applies — detect the change in updateTownConfig and restart the mayor session with the new model.

Acceptance Criteria

• role_models field added to town config schema (optional, backward compatible)
• Settings UI shows per-role model overrides with "Use default" option
• Agent dispatch resolves model per-role with fallback to default_model
• Changing a role's model takes effect on the next agent dispatch for that role
• Mayor model change triggers session restart (fix(gastown): Changing default model in town settings does not update the mayor'\''s running session #1438)
• Existing towns without role_models continue working unchanged

References

• feat(gastown): Replace default model text input with model selector dropdown in town settings #1430 — Model selector dropdown (replaces text input)
• fix(gastown): Changing default model in town settings does not update the mayor'\''s running session #1438 — Mayor session restart on model change
• container/src/agent-runner.ts — buildKiloConfigContent(), model resolution
• src/dos/town/actions.ts — dispatch_agent action, model passed to container

[kilo-code-bot]

This issue appears to be a duplicate of #1438.

fix(gastown): Changing default model in town settings does not update the mayor'\''s running session (#1438)

Similarity score: 91%

This comment was generated by Kilo Auto-Triage.

[maphew]

@kilo-code-bot this is not a duplicate. The other issue is about an applied model change not being reflected in running sessions. This issue is about setting a default model for each role across the town.