feat: select notes agent profiles directly

[yattdev]

Overview

The Notes plugin's "Enhance with AI" setting previously exposed Kandev's utility-prompt catalog (format: utility-agent) instead of the platform agent profiles the user actually wants to select. This release switches Notes to the new format: agent-profile plugin-config field so the picker in Settings → Plugins → Notes lists eligible platform agent profiles directly, and so the persisted agent_profile value is invoked by the host without any utility/custom-prompt lookup.

Changes

• Replace the utility_agent config_schema entry with agent_profile (format: agent-profile).
• Classify unset, missing, deleted, or ineligible profile selections as configuration failures and return HTTP 412 with actionable instructions pointing to the Notes settings page; keep genuine execution failures on HTTP 502.
• Update the settings-page actions and "Enhance with AI" copy so they reference a single direct profile selection and no longer route users to Settings → Utility Agents to define a custom utility prompt.
• Pin the new field name/format plus the release metadata in the manifest contract test, and refresh README/CHANGELOG to describe the agent-profile workflow, eligibility requirements (enabled, global, non-CLI-passthrough), compatibility expectations, and privacy impact.

Motivation

Listing utility prompts misled users into configuring Notes with identifiers the host could not execute as an agent profile, while requiring a duplicate custom prompt in Settings → Utility Agents added setup friction. Storing the agent profile ID itself keeps what users see, save, and execute aligned.

Testing

• make test (server + UI bundle tests)
• make vet
• make package-host producing kandev-plugin-notes-0.5.0.tar.gz
• Host smoke test on a build with direct agent-profile invocation support: install the packaged plugin, open Settings → Plugins → Notes, select an eligible Claude/Codex agent profile, save and reload, run Enhance with AI, and exercise missing/disabled profile recovery.

Screenshots

Notes settings page with the direct Agent profile field:

Agent profile picker open on eligible platform profiles:

Breaking Changes

• Configuration contract change. Notes now reads the agent profile from agent_profile. Existing installations must re-select an eligible profile in Settings → Plugins → Notes; the host falls back to a legacy utility_agent value only when agent_profile is unset.
• Minimum host version. This release requires a Kandev build that includes direct agent-profile invocation support (agent-profile schema rendering plus profile-preferred InvokeUtilityAgent execution). Installing it on an older build leaves the picker without usable options.