diff --git a/src/cli/index.ts b/src/cli/index.ts
index 3b153983..9b38b33c 100644
--- a/src/cli/index.ts
+++ b/src/cli/index.ts
@@ -33,6 +33,7 @@ import { runFlushMemory } from "../commands/flush-memory.js";
 import { maybeAutoBackfillMemory } from "../skillify/spawn-backfill-memory-worker.js";
 import { confirm, detectPlatforms, allPlatformIds, log, promptLine, warn, type PlatformId } from "./util.js";
 import { getVersion } from "./version.js";
+import { docsInstallLines } from "../docs/install-hint.js";
 import { runUpdate } from "./update.js";
 import { renderCliHelpBlock } from "./skillify-spec.js";
 import { maybeAutoMineLocal } from "../skillify/spawn-mine-local-worker.js";
@@ -395,6 +396,9 @@ async function runInstallAll(args: string[]): Promise<void> {
     log("Mining your past sessions for team memory in the background — sign in, then run `hivemind memory flush` to push.");
   }
 
+  log("");
+  for (const line of docsInstallLines()) log(line);
+
   log("");
   log("Done. Restart each assistant to activate hooks.");
 }
diff --git a/src/docs/docs-suggest.ts b/src/docs/docs-suggest.ts
new file mode 100644
index 00000000..e206e74a
--- /dev/null
+++ b/src/docs/docs-suggest.ts
@@ -0,0 +1,125 @@
+/**
+ * SessionStart "docs not set up" suggestion — the one place the agent learns
+ * that Hivemind CAN maintain docs for a repo that hasn't opted in yet.
+ *
+ * The wiki note (docs-context.ts) fires only for repos ALREADY opted into auto
+ * sync. That leaves a gap: a user in a real, indexed repo with docs OFF never
+ * hears the feature exists. This module fills exactly that gap, and only that
+ * gap — it is the inverse gate of `isAutoEnabled`.
+ *
+ * Two hard constraints shape the wording and the firing:
+ *   1. Anti prompt-injection. The note is descriptive capability disclosure,
+ *      never an imperative to the agent. It ends with an explicit "no action
+ *      needed unless the user asks" so the harness's injection heuristics read
+ *      it as context, not a smuggled instruction. Match docs-context.ts tone.
+ *   2. Show once per (org, project). A suggestion that reappears every session
+ *      is nagware. Firing is deduped through `~/.deeplake/docs-suggested.json`
+ *      (sibling of docs-auto.json), keyed on (orgId, projectKey) so nested
+ *      checkouts / worktrees of the same repo share one entry.
+ *
+ * Every read is hook-safe: a missing or corrupt registry is an empty registry,
+ * never a throw. `docsSuggestNote` is a PURE function (no writes) so the caller
+ * decides — and best-effort guards — the `markSuggested` write.
+ */
+
+import { mkdirSync, readFileSync, renameSync, writeFileSync } from "node:fs";
+import { homedir } from "node:os";
+import { dirname, join } from "node:path";
+
+export interface SuggestedEntry {
+  orgId: string;
+  /** Repo project key (deriveProjectKey(cwd).key). */
+  project: string;
+  /** Display-only: where the suggestion last fired from. */
+  path: string;
+  suggestedAt: string;
+}
+
+export interface SuggestedRegistry {
+  entries: SuggestedEntry[];
+}
+
+export function suggestedRegistryPath(): string {
+  return process.env.HIVEMIND_DOCS_SUGGESTED_FILE ?? join(homedir(), ".deeplake", "docs-suggested.json");
+}
+
+/** Read the registry. Missing/corrupt file → empty (hooks must never crash). */
+export function readSuggestedRegistry(file = suggestedRegistryPath()): SuggestedRegistry {
+  try {
+    const raw = JSON.parse(readFileSync(file, "utf-8")) as Partial<SuggestedRegistry>;
+    if (!Array.isArray(raw.entries)) return { entries: [] };
+    const entries = raw.entries.filter(
+      (e): e is SuggestedEntry =>
+        !!e && typeof e === "object" &&
+        typeof (e as SuggestedEntry).orgId === "string" &&
+        typeof (e as SuggestedEntry).project === "string",
+    );
+    return { entries };
+  } catch {
+    return { entries: [] };
+  }
+}
+
+/** Has the docs suggestion already fired for (org, project)? Hook-safe, read-only. */
+export function wasSuggested(orgId: string, project: string, file = suggestedRegistryPath()): boolean {
+  return readSuggestedRegistry(file).entries.some(
+    (e) => e.orgId === orgId && e.project === project,
+  );
+}
+
+/**
+ * Record that the suggestion fired for (org, project). Atomic (tmp + rename)
+ * and idempotent — a repeat call updates `path`/`suggestedAt` in place rather
+ * than appending a duplicate. Best-effort by contract: the caller wraps this
+ * so a write failure never breaks SessionStart.
+ */
+export function markSuggested(
+  orgId: string,
+  project: string,
+  path: string,
+  suggestedAt: string,
+  file = suggestedRegistryPath(),
+): void {
+  const reg = readSuggestedRegistry(file);
+  const existing = reg.entries.find((e) => e.orgId === orgId && e.project === project);
+  if (existing) {
+    existing.path = path;
+    existing.suggestedAt = suggestedAt;
+  } else {
+    reg.entries.push({ orgId, project, path, suggestedAt });
+  }
+  mkdirSync(dirname(file), { recursive: true });
+  const tmp = `${file}.tmp`;
+  writeFileSync(tmp, JSON.stringify(reg, null, 1) + "\n");
+  renameSync(tmp, file);
+}
+
+const NOTE = `
+
+DOCS (not set up for this repo): Hivemind can maintain per-file and per-subsystem documentation that stays in sync with the code on every commit, searchable under ~/.deeplake/memory/docs/. This repo hasn't opted in. If the user would find persistent, commit-fresh code docs useful, they can enable them by running \`hivemind docs sync\` (one-time consent, then auto-maintained on commits). Purely informational — no action needed unless the user asks about it.`;
+
+/**
+ * The suggestion note, or "" when it should not fire. Returns "" — never
+ * throws — when docs are already enabled, when the suggestion already fired,
+ * when this is not an indexed code repo (no local graph), or on any registry
+ * read failure. PURE: does not write; the caller records via `markSuggested`.
+ */
+export function docsSuggestNote(args: {
+  orgId: string;
+  project: string;
+  /** True when a local code graph exists for this repo — the "real repo" gate. */
+  graphPresent: boolean;
+  isAutoEnabledFn: (orgId: string, project: string) => boolean;
+  wasSuggestedFn?: (orgId: string, project: string) => boolean;
+}): string {
+  const { orgId, project, graphPresent, isAutoEnabledFn } = args;
+  const wasSuggestedFn = args.wasSuggestedFn ?? wasSuggested;
+  try {
+    if (!graphPresent) return "";
+    if (isAutoEnabledFn(orgId, project)) return "";
+    if (wasSuggestedFn(orgId, project)) return "";
+    return NOTE;
+  } catch {
+    return "";
+  }
+}
diff --git a/src/docs/install-hint.ts b/src/docs/install-hint.ts
new file mode 100644
index 00000000..adece8be
--- /dev/null
+++ b/src/docs/install-hint.ts
@@ -0,0 +1,19 @@
+/**
+ * Docs onboarding shown once, in the `hivemind install` output — the visible
+ * counterpart to the (model-only) SessionStart note.
+ *
+ * `hivemind install` runs on a TTY, so this is the honest place to TELL the
+ * user the docs feature exists and, crucially, how to turn it ON and OFF.
+ * Both directions in one block so the user is never stuck: enabling and
+ * disabling are one command each, and status is discoverable.
+ */
+
+/** Lines describing docs enable/disable, for the install summary. */
+export function docsInstallLines(): string[] {
+  return [
+    "Docs (optional): keep per-file and per-subsystem documentation in sync with your code on every commit.",
+    "  Enable in a repo:  hivemind docs sync    (one-time consent; opt into per-commit auto-sync when asked)",
+    "  Turn it off later: hivemind docs auto off",
+    "  Check status:      hivemind docs list",
+  ];
+}
diff --git a/src/hooks/session-start.ts b/src/hooks/session-start.ts
index cc71ec92..e0440ff1 100644
--- a/src/hooks/session-start.ts
+++ b/src/hooks/session-start.ts
@@ -9,6 +9,8 @@
 import { fileURLToPath } from "node:url";
 import { maybeSpawnDocsRefresh } from "../docs/auto-refresh-trigger.js";
 import { docsWikiContextNote } from "../docs/docs-context.js";
+import { docsSuggestNote, markSuggested } from "../docs/docs-suggest.js";
+import { isAutoEnabled } from "../docs/auto-registry.js";
 import { deriveProjectKey } from "../utils/repo-identity.js";
 import { dirname, join } from "node:path";
 import { homedir } from "node:os";
@@ -326,10 +328,27 @@ async function main(): Promise<void> {
   // Docs wiki note — the agent has no other way to learn the wiki exists.
   // Gated on the same local consent registry as auto sync (no network),
   // and worded on-demand, never wiki-first (see docs-context.ts).
+  const docsProject = deriveProjectKey(input.cwd ?? process.cwd()).key;
   const docsNote = creds?.token
-    ? docsWikiContextNote(creds.orgId ?? "", deriveProjectKey(input.cwd ?? process.cwd()).key)
+    ? docsWikiContextNote(creds.orgId ?? "", docsProject)
     : "";
 
+  // Docs "not set up" suggestion — inverse gate of docsNote. Fires once per
+  // (org, project) for a real indexed repo (graph present) that hasn't opted
+  // into docs, so the agent can surface the feature IF the user asks. Wording
+  // is descriptive, not imperative (anti prompt-injection); see docs-suggest.ts.
+  let suggestNote = "";
+  if (creds?.token && !docsNote && graphLine) {
+    const docsOrg = creds.orgId ?? "";
+    suggestNote = docsSuggestNote({ orgId: docsOrg, project: docsProject, graphPresent: true, isAutoEnabledFn: isAutoEnabled });
+    if (suggestNote) {
+      // Best-effort: a suggestion write must never break SessionStart.
+      try {
+        markSuggested(docsOrg, docsProject, input.cwd ?? process.cwd(), new Date().toISOString());
+      } catch { /* ignore — worst case the note shows again next session */ }
+    }
+  }
+
   // Disclose the EFFECTIVE identity (after any `.hivemind` overlay), so a
   // directory that routes elsewhere (or opts out) is never silent.
   const effConfig = dirRes?.config ?? baseConfig;
@@ -349,7 +368,7 @@ async function main(): Promise<void> {
   const withRules = rulesBlock
     ? `${baseContext}\n\n${rulesBlock}`
     : baseContext;
-  const additionalContext = `${withRules}${graphNote}${docsNote}`;
+  const additionalContext = `${withRules}${graphNote}${docsNote}${suggestNote}`;
 
   console.log(JSON.stringify({
     hookSpecificOutput: {
diff --git a/tests/shared/docs-install-hint.test.ts b/tests/shared/docs-install-hint.test.ts
new file mode 100644
index 00000000..8e0c832d
--- /dev/null
+++ b/tests/shared/docs-install-hint.test.ts
@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+import { docsInstallLines } from "../../src/docs/install-hint.js";
+
+describe("docsInstallLines (install-time docs onboarding)", () => {
+  it("explains both enabling and disabling in one block", () => {
+    const text = docsInstallLines().join("\n");
+    // Enable path.
+    expect(text).toContain("hivemind docs sync");
+    // Disable path — the user must never be stuck after opting in.
+    expect(text).toContain("hivemind docs auto off");
+    // Status is discoverable.
+    expect(text).toContain("hivemind docs list");
+  });
+
+  it("is a non-empty list of plain strings (safe to feed line-by-line to log)", () => {
+    const lines = docsInstallLines();
+    expect(lines.length).toBeGreaterThan(0);
+    expect(lines.every((l) => typeof l === "string" && l.length > 0)).toBe(true);
+  });
+});
diff --git a/tests/shared/docs-suggest.test.ts b/tests/shared/docs-suggest.test.ts
new file mode 100644
index 00000000..5773f551
--- /dev/null
+++ b/tests/shared/docs-suggest.test.ts
@@ -0,0 +1,110 @@
+import { mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import {
+  docsSuggestNote,
+  markSuggested,
+  readSuggestedRegistry,
+  wasSuggested,
+} from "../../src/docs/docs-suggest.js";
+
+describe("docsSuggestNote (SessionStart 'docs not set up' hint)", () => {
+  it("fires for a real indexed repo that hasn't opted in and wasn't suggested", () => {
+    const note = docsSuggestNote({
+      orgId: "org-a",
+      project: "proj-1",
+      graphPresent: true,
+      isAutoEnabledFn: () => false,
+      wasSuggestedFn: () => false,
+    });
+    expect(note).toContain("DOCS (not set up for this repo)");
+    expect(note).toContain("hivemind docs sync");
+    // Anti prompt-injection: descriptive, ends with an explicit no-op-by-default.
+    expect(note).toContain("no action needed unless the user asks");
+    expect(note).not.toMatch(/\byou (must|should)\b/i);
+    expect(note.startsWith("\n\n")).toBe(true); // appends cleanly after docsNote
+  });
+
+  it("returns '' when docs are already enabled (inverse gate of the wiki note)", () => {
+    expect(
+      docsSuggestNote({
+        orgId: "org-a",
+        project: "proj-1",
+        graphPresent: true,
+        isAutoEnabledFn: () => true,
+        wasSuggestedFn: () => false,
+      }),
+    ).toBe("");
+  });
+
+  it("returns '' when the suggestion already fired for this (org, project)", () => {
+    expect(
+      docsSuggestNote({
+        orgId: "org-a",
+        project: "proj-1",
+        graphPresent: true,
+        isAutoEnabledFn: () => false,
+        wasSuggestedFn: () => true,
+      }),
+    ).toBe("");
+  });
+
+  it("returns '' when this is not an indexed code repo (no local graph)", () => {
+    let asked = false;
+    const note = docsSuggestNote({
+      orgId: "org-a",
+      project: "proj-1",
+      graphPresent: false,
+      isAutoEnabledFn: () => { asked = true; return false; },
+      wasSuggestedFn: () => false,
+    });
+    expect(note).toBe("");
+    expect(asked).toBe(false); // graph gate short-circuits before any registry read
+  });
+
+  it("fail-closed: a throwing registry read yields '' — never breaks SessionStart", () => {
+    expect(
+      docsSuggestNote({
+        orgId: "org-a",
+        project: "proj-1",
+        graphPresent: true,
+        isAutoEnabledFn: () => { throw new Error("corrupt registry"); },
+        wasSuggestedFn: () => false,
+      }),
+    ).toBe("");
+  });
+});
+
+describe("suggested registry (dedup persistence)", () => {
+  let dir: string;
+  let file: string;
+  beforeEach(() => {
+    dir = mkdtempSync(join(tmpdir(), "docs-suggested-"));
+    file = join(dir, "docs-suggested.json");
+  });
+  afterEach(() => rmSync(dir, { recursive: true, force: true }));
+
+  it("markSuggested then wasSuggested round-trips for the same (org, project)", () => {
+    expect(wasSuggested("org-a", "proj-1", file)).toBe(false);
+    markSuggested("org-a", "proj-1", "/repo", "2026-07-10T00:00:00.000Z", file);
+    expect(wasSuggested("org-a", "proj-1", file)).toBe(true);
+    // A different project under the same org is independent.
+    expect(wasSuggested("org-a", "proj-2", file)).toBe(false);
+  });
+
+  it("markSuggested is idempotent — a repeat updates in place, no duplicate row", () => {
+    markSuggested("org-a", "proj-1", "/repo", "2026-07-10T00:00:00.000Z", file);
+    markSuggested("org-a", "proj-1", "/repo/again", "2026-07-11T00:00:00.000Z", file);
+    const reg = readSuggestedRegistry(file);
+    expect(reg.entries).toHaveLength(1);
+    expect(reg.entries[0].path).toBe("/repo/again");
+    expect(reg.entries[0].suggestedAt).toBe("2026-07-11T00:00:00.000Z");
+  });
+
+  it("a corrupt registry file reads as empty — never throws", () => {
+    writeFileSync(file, "{ not json");
+    expect(readSuggestedRegistry(file).entries).toEqual([]);
+    expect(wasSuggested("org-a", "proj-1", file)).toBe(false);
+  });
+});