Allow change the modes, models and select agents to be used

[wilcorrea]

Allow changing ACP mode, model, and agent in-session

Problem

ACP mode/model/agent are not fully controllable from the session UI.
Need runtime selectors + persistence, without breaking current planning workflow.

Goals

• Add runtime selectors for mode, model, agent.
• Persist per-session selections.
• Apply workspace defaults for new/empty sessions.
• Keep deterministic behavior while streaming.
• Gracefully degrade when ACP does not expose model/agent options.

Out of Scope

• Whisper model UX changes.
• Non-ACP provider integration.

---

Layout Changes

Current (header has session/phase/connection only)

┌─────────────────────────────────────────────────────────────────────────────┐
│ [Session Name] [#sessionId] [Phase ▼] [Connect/Reconnect] [window actions]│
├─────────────────────────────────────────────────────────────────────────────┤
│ Chat panel                                              | Plan panel       │
└─────────────────────────────────────────────────────────────────────────────┘

Proposed (add ACP controls in header as chips)

┌─────────────────────────────────────────────────────────────────────────────┐
│ [Session Name] [#sessionId] [Phase ▼] [Mode ▼] [Model ▼] [Agent ▼] [Adv ▼]│
│ [Connect/Reconnect]                                         [window actions]│
├─────────────────────────────────────────────────────────────────────────────┤
│ Chat panel                                              | Plan panel       │
└─────────────────────────────────────────────────────────────────────────────┘

Header behavior

• Controls disabled when:
  • streaming (isStreaming=true)
  • disconnected
• Model/Agent hidden or disabled with “Unavailable from ACP” when options are absent.
• Keep workflow auto-switch:
  • planning => force plan mode
  • approve => force agent mode
  • append notice message when auto-switched.

---

Technical Plan

1) ACP contract support (Rust + TS)

• Extend ACP types with config options:
  • available config options
  • selected config options
• Add Tauri command:
  • acp_set_config_option(workspace_id, session_id, config_id, option_id)
  • maps to ACP session/set_config_option
• Register command in invoke_handler.
• Parse config-option update events in useAcpSession.

2) Persistence

• Add acp_preferences_json TEXT NOT NULL DEFAULT '{}' to sessions.
• Add table workspace_acp_defaults:
  • workspace_path TEXT PRIMARY KEY
  • acp_preferences_json TEXT NOT NULL DEFAULT '{}'
  • updated_at TEXT NOT NULL
• Add commands:
  • session_update_acp_preferences(id, acp_preferences_json)
  • workspace_acp_defaults_get(workspace_path)
  • workspace_acp_defaults_set(workspace_path, acp_preferences_json)
• Remove workspace defaults in forget_workspace_data.

3) Preference application order

• On session init:
  1. load ACP session info
  2. load session prefs
  3. if empty -> load workspace defaults
  4. apply mode first, then config options
  5. ignore stale/invalid selections safely
• On successful user selection:
  • update ACP
  • persist session prefs
  • upsert workspace defaults

4) UI implementation

• Add AcpSessionControls component in ActiveSessionView header.
• Controls:
  • Mode selector (existing ACP modes)
  • Model selector (ACP config detected as model)
  • Agent selector (ACP config detected as agent)
  • Advanced selector for remaining config options
• Update useAcpSession return contract:
  • expose structured modes
  • expose config options + selected values
  • add setConfigOption(configId, optionId)

5) i18n

• EN/PT keys for:
  • labels (Mode, Model, Agent, Advanced)
  • disabled/unavailable text
  • auto-switch notice

---

Data Contract

acp_preferences_json

{
  "modeId": "string | null",
  "selectedConfigOptions": {
    "configId": "optionId"
  }
}

Resolution rules

• Session prefs override workspace defaults.
• Workspace defaults apply only when session prefs are empty.
• Invalid IDs are dropped (no hard failure).

---

Acceptance Criteria

• User can change mode at runtime.
• User can change model/agent when ACP exposes those options.
• Selections persist per session and restore on resume.
• New/empty sessions inherit workspace defaults.
• Selectors disabled during streaming.
• Missing model/agent options do not break UI.
• Plan workflow auto-switch still works and shows notice.

---

Test Plan

Frontend

• useAcpSession parses mode/config update events correctly.
• Preference merge logic tests:
  • session > workspace defaults
  • fallback to workspace defaults
  • stale IDs ignored
• AcpSessionControls rendering tests:
  • normal state
  • streaming disabled state
  • unavailable model/agent state
• selector action tests invoke expected Tauri commands.

Backend

• migration tests for new column/table.
• command tests for get/set prefs.
• command test for acp_set_config_option.

---

References

• Repository
• ACP overview
• ACP spec
• ACP session config options
• Current useAcpSession.ts
• Current ActiveSessionView.tsx
• Current acp/commands.rs
• Current acp/types.rs
• Current sessions.rs