feat: graph context injection — the session's prior knowledge, steered in at session start (vision-context-injection.md)

One shot per chat, fired at the first turn's onFinish: the session's
topic (its only typed message) is embedded as an EmbeddingGemma retrieval
query; the semantically closest graph propositions are selected under the
session's token budget (pure budget, no similarity threshold — the
decided doctrine) and delivered as a marker-only steer through the wake
pipeline, queuing behind pending questions like every sub-agent result.

- contracts: ChatSettings.graphContextTokens (default 1024, max 4096,
  step 128, 0 = off); GraphContextData + graphContextText; the
  graph-context JobKind + buildGraphContextSteer (id steer_ctx_<chatId>)
- core/graph-context.ts: brute-force cosine top-K, greedy chars/4 fill
  under budget, most-recent UnderstandingLevel fold, count cap 64,
  parse-don't-cast at the marker seam
- server: embedQuery (role-asymmetric query format, same warm singleton
  — vector-space parity by construction); the runner (startGraphContext-
  Injection one-shot gates; runGraphContextJob validates ledger parity);
  wake branches (chatIdOf/jobIdOf, finalizeJob done, recoverStaleJobs
  re-deliver or contextRespawn); abortJob kills context jobs SILENTLY
  (nothing was promised in the lesson); turn-service trigger seam
- adapter: data-graph-context flattens to the canonical block (malformed
  parts have no model face)
- UI: the budget slider (home dock + /chat/new draft, the session-data
  strip); the quiet SystemLine "~537 · 10 propositions"; dock kind
  "Knowledge context"; model-picker PUT now spreads settings (a model
  pick can no longer clear the sibling override)

Live-smoked end to end on the real embedder + real GLM: seeded ledger
(10 propositions), session on "modal logic: possible worlds and the
necessity box" — job in the dock, queued behind the prober's question,
delivered on the answer, SystemLine in the transcript, wake turn reads
the block and continues the probe. Gates: tsc, lint, 459/459, build.

components/home.tsx

@@ -4,6 +4,7 @@ import { useState } from "react";
 import { useRouter } from "next/navigation";
 import { CornerDownLeftIcon } from "lucide-react";
 import { GraphView } from "@/components/graph-view";
+import { GraphContextControl, effectiveContextTokens } from "@/components/graph-context-control";
 import { SidebarToggle } from "@/components/sidebar";
 import { StatsBar } from "@/components/stats-bar";
 import type { ChatSettings, TurnUsage } from "@/src/core";
@@ -71,6 +72,17 @@ export function Home() {
 			    px-4) so nothing shifts when a session starts (owner). */}
 			<div className="pointer-events-none absolute inset-x-0 bottom-0 pb-5">
 				<div className="pointer-events-auto mx-auto w-full max-w-[46rem] px-4">
+					{/* The session-data strip (vision-context-injection.md): what the
+					    graph will contribute to the session, decided before the session
+					    starts. Rides the same lifted settings as the model picker. */}
+					<div className="mb-1.5">
+						<GraphContextControl
+							value={effectiveContextTokens(settings)}
+							onChange={(tokens) =>
+								setSettings((s) => ({ ...s, graphContextTokens: tokens }))
+						}
+						/>
+					</div>
 					<form
 						className="flex items-end gap-1.5 rounded-2xl border bg-card p-1.5 shadow-lg"
 					onSubmit={(e) => {