BoardTab and SettingsTab keep a 'fast path' prop nothing can ever supply — feed it or delete it #623

What was found

GET /v1/instances/my/instances deliberately strips two capability fields before replying:

// workers/api/src/routes/instances.ts:315
const { boardColumns: _bc, settingsSchema: _ss, ...lightCaps } = fullCaps;

with a measured reason on the line above it — the full set cost ~83 KB for 28 instances, and the list only needs the routing fields. That is a considered decision and #617 did not touch it.

What #617 DID find is that my/instances is the only endpoint any consumer of the console's Instance type calls (pages/Dashboard.tsx:31, pages/Browse.tsx:39, pages/InstanceDetail.tsx:304, tabs/TeamworkSection.tsx:116). So InstanceDetail was passing two permanently-undefined props down:

boardColumns: instance?.capabilities?.boardColumns,      // always undefined
settingsSchema: instance?.capabilities?.settingsSchema,  // always undefined

SettingsTab.tsx:58-60 even documents the intent — "the schema prop is the fast path; the GET also returns fields so the form never depends on a stale instance-list cache" — for an optimisation that has never once fired.

Current state after #617

The two fields were removed from Instance.capabilities and the two pass-throughs deleted. Behaviour is unchanged, because both tabs already read the real values from their own fetch:

• BoardTab.tsx:68 — serverCols?.length ? serverCols : (columns?.length ? columns : GENERIC_COLUMNS), with serverCols from /board.
• SettingsTab.tsx:127 — if (d.fields?.length) setAgentFields(d.fields) from /settings.

But the props themselves (SurfaceCtx.boardColumns / .settingsSchema in lib/surfaces.tsx:56,58, threaded at :184, :200, :338) still exist and now have no supplier at all.

The decision this issue is for

Two coherent options; pick one rather than leaving a prop with no producer:

1. Delete the chain. Remove boardColumns/settingsSchema from SurfaceCtx and from BoardTab/SettingsTab's props, so the second fetch is plainly the only path. Cheapest, and honest.
2. Actually supply it. Fetch the full capabilities on the instance detail route (not the list), so the fast path exists for real. This is the only option that removes the first-paint flicker — the board briefly shows GENERIC_COLUMNS before /board answers, and the agent-settings block is briefly empty.

Option 2 is the only one with a user-visible benefit, and it is worth measuring first: both symptoms self-heal within one round trip, which is exactly why nobody has reported them.

Verified vs inferred

• Verified: the strip at instances.ts:315 and its comment; that all four Instance consumers call only my/instances; both fallback lines; that no other code path assigns either prop.
• Inferred: that the first-paint flicker is perceptible. Not measured — it may be invisible on a fast connection, which would settle this for option 1.

Files: store/console/src/lib/surfaces.tsx, store/console/src/tabs/BoardTab.tsx, store/console/src/tabs/SettingsTab.tsx, workers/api/src/routes/instances.ts