D86 — Connect UX: agent subsets, 0-KB diagnostics, absolute paths

Status: implemented (2026-07-24).

Context. A healthy service with no mounted KB returned 400 kb parameter required from /mcp, which connect described as an unreachable local service. connect and disconnect also accepted only one provider or all, despite the configurator already supporting all four providers independently; and their success output showed paths relative to the target directory, making a write look as if it had happened in the current directory.

Decision. - Health-aware probe. internal/client.Health derives /health from the configured MCP URL and parses the additive ready and kbs fields defensively. A false ready, or an explicitly empty kbs list from a pre-D84 server, produces the first-KB guidance (kb create, then service restart); only an actually unreachable loopback service offers installation. A missing ready/kbs remains compatible with older healthy servers. - Provider subsets. connect and disconnect accept --agents claude,codex as a validated comma-separated selection; it cannot be combined with the positional provider. The interactive Bubble Tea form exposes one checkbox per supported provider, preselected from the detected set. - Unambiguous output. configurator.Apply records and returns absolute config paths while retaining relative paths for provider-native file lookup. A successful non-dry-run connect also tells the user to restart the selected agent sessions so their MCP clients reload the tools.

Rationale. Health is the appropriate readiness signal for a client-side onboarding decision: it distinguishes a server that needs its first KB from one that is down without making /mcp's transport error carry product guidance. CSV and checkboxes cover the common partial-install case without adding a new provider model, while absolute paths make the side effects of configuration safe to verify from any working directory.