wave 7: the prober reads its map — graph-context injection dies whole

The owner's zero-configuration ruling (2026-09-23): nothing configures
the graph beyond chat models. The prior-knowledge injection — its budget
dial, its runner, its marker part, its dock/dispatch entries — is
removed across all bands; the prober now reads the learner's persistent
knowledge map on demand through two gated tools instead:

- list_sessions: every birth session, names + kinds + counts + dates
  (graphSessionIndex, Platform's core seam)
- list_propositions(session): what was born there + the session's own
  latest understanding level + that evaluation's date
  (graphSessionPropositions) — names/levels/dating ONLY, no statement
  text (owner ruling: the map's organization is the prober's business,
  its prose is not)

Registered via createProberTools when chat-handler passes graphStore
(the graphToolsEnabled gate decided server-side, per-turn fresh); the
prober doctrine gains the map-review nudge at session start.

Also: runner's JobKind special-casing collapses (KIND_ROLE/KIND_RUNNERS
are plain records again), semantic-clusters.ts dies with its test, the
embedder dep's doc tells the wave-7 stub story, and ports.ts's
readClusterLabels/readNamingRuns surface stays untouched for Platform's
ledger-port interlude.

848/848 tests, typecheck/lint/build green.

src/server/chat-handler.ts

@@ -12,6 +12,7 @@ import { effectiveSettings, stores } from "./stores.ts";
 import { searchAvailable, searchProvider } from "./search.ts";
 import {
 	extractionEnabled,
+	graphToolsEnabled,
 	resolveConversationSpec,
 	resolveRoleSpec,
 } from "../core/settings-resolution.ts";
@@ -274,6 +275,10 @@ export async function handleChatRequest(
 						jobStore: stores.jobStore,
 						spawn: (job, input) => void jobRunner.runJob(job.id, input),
 						searchAvailable,
+						// The map reader (wave 7): the prober reads the learner's
+						// knowledge graph through tools when the gate opens —
+						// graph master switch AND the agent.graphTools toggle.
+						...(graphToolsEnabled(effective) ? { graphStore: stores.graphStore } : {}),
 					},
 					agentOpts,
 				);