Add configurable Workspace Search result-count controls for admins, agents, and chat users

Summary

Add configurable Workspace Search result-count controls so admins can define the default retrieval breadth and optionally allow assigned-knowledge agents and chat users to override it. In normal chat, users can open a compact control in the Grounded Search panel and choose a persistent personal default from 5 to 100 results.

User Value

Different searches need different retrieval breadth. A focused lookup may need only a few chunks, while broad discovery may benefit from many more. Admins need a bounded policy that manages latency and token usage, and users need a quick way to tune normal Workspace Search without repeating instructions or changing the value for every new conversation.

Proposed Behavior

Admin Settings

• Add a new Chat tab in Admin Settings for chat-specific policies and controls.
• Add a Workspace Search default result-count setting bounded from 5 to 100.
• Add an independent enable/disable setting that determines whether users may set a personal Workspace Search result count.
• Retain a separate policy controlling whether assigned-knowledge agents may override the admin default.
• When user overrides are disabled, hide the user control and enforce the admin default server-side.

Chat Experience

• Add a compact icon button to the Grounded Search controls. Clicking it opens an accessible popover containing a slider and the selected numeric value.
• Show and apply the control only when the Action selection is Search.
• Do not show or apply this value to Analyze or Compare actions.
• Do not apply this setting to Web Search, URL access, Source Review/deep research, or unrelated search surfaces.
• Bound the slider to integer values from 5 through 100.
• Initialize the control from the user's saved preference when one exists; otherwise use the admin default.
• Persist changes in the user's settings so the selected value becomes that user's default for normal Workspace Search in the current and future conversations.
• Allow the user to move the slider before later searches and provide a clear way to reset the personal preference to the current admin default.
• Label the setting as a maximum retrieval count because fewer results may be available after access filtering, relevance ranking, and deduplication.

Retrieval and Policy Enforcement

• Send the effective result count with normal Workspace Search requests and apply it to the centralized top_n retrieval path.
• Treat admin policy as authoritative: validate values server-side, ignore unauthorized overrides, and constrain malformed or stale saved preferences to the current 5-100 range.
• Include the effective result count in search cache identity so results cached under one limit are not reused for another.
• For normal non-agent Workspace Search, use this precedence: allowed user preference, then admin default.
• Keep assigned-knowledge agent overrides separate from the normal chat preference; when agent retrieval is active, use the allowed per-agent value or the admin default according to the agent policy.
• Existing users without a saved preference inherit the current admin default without migration or failures.

Acceptance Criteria

• Admin Settings includes a new Chat tab with a 5-100 Workspace Search default and a user-override enable/disable setting.
• Admins can enable or disable assigned-knowledge agent overrides independently from chat user overrides.
• When user overrides are enabled and Search is selected, Chat exposes an accessible icon-triggered slider showing the active value from 5 through 100.
• The control is hidden or inactive for Analyze and Compare, and its value does not affect those actions.
• The setting affects normal Workspace Search only and does not alter Web Search, URL access, Source Review/deep research, or unrelated retrieval paths.
• A user's selection is saved as a user preference and becomes their default across conversations and sessions.
• Users can change the preference at any time and reset it to the current admin default.
• Disabling user overrides hides the control and causes the server to use the admin default regardless of client-supplied or previously saved values.
• Server-side validation enforces authorization and the 5-100 range, including after an admin changes the configured bounds or default.
• The effective value reaches the centralized Workspace Search top_n path and participates in cache identity.
• Assigned-knowledge agent behavior remains isolated and follows its separately configured override policy.
• Functional and UI tests cover admin settings, Search-only visibility, user persistence, reset behavior, disabled policy, request tampering, bounds, retrieval propagation, and cache separation.

Notes

• The current local retrieval anchor is application/single_app/functions_search.py, where SEARCH_DEFAULT_TOP_N = 12, SEARCH_MAX_TOP_N = 500, and normalize_search_top_n() centralize existing defaults and bounds.
• The normal Search/Analyze/Compare selector lives in the Grounded Search panel in application/single_app/templates/chats.html; request construction is handled in application/single_app/static/js/chat/chat-messages.js.
• User-level persistence can use the existing user settings store rather than conversation metadata because this selection is intended to follow the user into future conversations.
• Assigned knowledge configuration remains in application/single_app/templates/_agent_modal.html and application/single_app/static/js/agent_modal_stepper.js.