diff --git a/README.md b/README.md
index 9d7d95b..5ddb26d 100644
--- a/README.md
+++ b/README.md
@@ -277,9 +277,10 @@ through the stations — narrated click by click in
    they name; the judgement around them is drafted, and anything the scan
    could not ground says `UNVERIFIED`. The wizard does not pretend to know
    your architecture ([`knowledge/decisions/0015-onboarding-reads-the-repo-before-it-drafts.md`](knowledge/decisions/0015-onboarding-reads-the-repo-before-it-drafts.md)).
-   An `AGENTS.md` or `CLAUDE.md` you already have is **not rewritten** — specd's
-   rules are appended below yours behind a `<!-- specd:begin -->` fence, which
-   a later grounding run updates in place.
+   An `AGENTS.md` or `CLAUDE.md` you already have is **not rewritten**, and not
+   restated: specd appends a short block with the four rules its own machinery
+   enforces, behind a `<!-- specd:begin -->` fence a later grounding run updates
+   in place. Your own agreements are left to say everything else.
 3. **Adopt** — merge the setup branch. Merging *is* the adoption signal;
    specd indexes `knowledge/` the moment the webhook lands (local mode has an
    "I merged it" button instead).
diff --git a/apps/web/lib/docs/concepts.ts b/apps/web/lib/docs/concepts.ts
index 25b180c..fcea294 100644
--- a/apps/web/lib/docs/concepts.ts
+++ b/apps/web/lib/docs/concepts.ts
@@ -171,7 +171,7 @@ export const CONCEPTS: DocCategory = {
         },
         {
           k: 'p',
-          text: 'If the repository already has an `AGENTS.md` or `CLAUDE.md`, **nothing in it is rewritten.** Your file stays exactly as it is and specd\'s rules are appended below it, fenced by `<!-- specd:begin -->` markers so a later grounding run updates only that block. Where the two sets disagree, yours came first and a human decides — the setup pull request says so, and `knowledge/open-questions.md` carries it as an item.',
+          text: 'If the repository already has an `AGENTS.md`, **nothing in it is rewritten** — and specd does not append a second set of engineering rules underneath. A team that wrote its own agreements has usually already said "read the docs first" and "docs ride the change"; restating that is worse than either copy, because an agent follows whichever it reads first. So specd appends a short block instead: the four rules its own machinery enforces, and where the knowledge base lives. It is fenced by `<!-- specd:begin -->` markers, so a later grounding run updates only that block.',
         },
         {
           k: 'ol',
diff --git a/packages/templates/src/agents-md.test.ts b/packages/templates/src/agents-md.test.ts
index 80bacf0..d23e620 100644
--- a/packages/templates/src/agents-md.test.ts
+++ b/packages/templates/src/agents-md.test.ts
@@ -5,9 +5,12 @@ import {
   mergeAgentsMd,
   mergeClaudeMd,
   renderAgentsMd,
+  renderAgentsSupplement,
   renderClaudeMd,
 } from './agents-md.js';
 
+const supplement = renderAgentsSupplement({ isPrimary: true, projectName: 'Acme' });
+
 const generated = renderAgentsMd({
   repoName: 'acme/api',
   stack: {
@@ -36,7 +39,7 @@ describe('mergeAgentsMd', () => {
   });
 
   it('keeps every line of an existing file and appends the specd block', () => {
-    const merged = mergeAgentsMd(theirs, generated);
+    const merged = mergeAgentsMd(theirs, generated, supplement);
 
     for (const line of theirs.trim().split('\n')) {
       expect(merged).toContain(line);
@@ -44,11 +47,39 @@ describe('mergeAgentsMd', () => {
     expect(merged).toContain(SPECD_BLOCK_BEGIN);
     expect(merged).toContain(SPECD_BLOCK_END);
     expect(merged.indexOf('Never touch')).toBeLessThan(merged.indexOf(SPECD_BLOCK_BEGIN));
-    expect(merged).toContain('Before implementing ANYTHING');
+  });
+
+  it('appends only what is specd\'s, not a second set of engineering rules', () => {
+    // A team that wrote its own AGENTS.md has usually said "read the docs
+    // first", "cite what you relied on", "docs ride the change" already, in
+    // its own words. Restating them under theirs is worse than either copy: an
+    // agent follows whichever it reads first.
+    const merged = mergeAgentsMd(theirs, generated, supplement);
+
+    expect(merged).not.toContain('Before implementing ANYTHING');
+    expect(merged).not.toContain('Knowledge first — no exceptions');
+    expect(merged).not.toContain('Do not invent the answer');
+
+    // What survives is the machinery a team cannot already have described.
+    expect(merged).toContain('specd spec pull <id>');
+    expect(merged).toContain('spec/<ID>-<slug>');
+    expect(merged).toContain('knowledge/specs/<ID>-<slug>.md');
+  });
+
+  it('says the team\'s rules win, since only they can resolve an overlap', () => {
+    expect(mergeAgentsMd(theirs, generated, supplement)).toMatch(
+      /agreements above still stand.*yours win/s,
+    );
+  });
+
+  it('still writes the whole document when the repo has no agreements to duplicate', () => {
+    // Nothing to talk over, so the full set of rules is the useful thing.
+    expect(mergeAgentsMd(null, generated, supplement)).toBe(generated);
+    expect(mergeAgentsMd('', generated, supplement)).toContain('Before implementing ANYTHING');
   });
 
   it('leaves the team the only H1 — the appended block is a section, not a rival document', () => {
-    const merged = mergeAgentsMd(theirs, generated);
+    const merged = mergeAgentsMd(theirs, generated, supplement);
     expect(merged.match(/^# /gm)).toHaveLength(1);
   });
 
@@ -56,23 +87,22 @@ describe('mergeAgentsMd', () => {
     // The fence is an HTML comment, and every markdown renderer hides those —
     // so on the pull request page a reader would see one continuous list of
     // rules with no idea which half arrived this morning.
-    const merged = mergeAgentsMd(theirs, generated);
-    expect(merged).toContain('## Working agreements added by specd');
-    expect(merged).toContain('Your own rules above came');
+    const merged = mergeAgentsMd(theirs, generated, supplement);
+    expect(merged).toContain('## specd — added by setup');
   });
 
   it('replaces its own block on a re-run instead of stacking a second copy', () => {
-    const first = mergeAgentsMd(theirs, generated);
-    const second = mergeAgentsMd(first, generated.replace('Stack:', 'Stack (rescanned):'));
+    const first = mergeAgentsMd(theirs, generated, supplement);
+    const second = mergeAgentsMd(first, generated, supplement.replace('specd spec pull', 'specd spec fetch'));
 
     expect(second.match(new RegExp(SPECD_BLOCK_BEGIN.slice(0, 20), 'g'))).toHaveLength(1);
-    expect(second).toContain('Stack (rescanned):');
+    expect(second).toContain('specd spec fetch');
     expect(second).toContain('Never touch `legacy/` without asking Priya.');
   });
 
   it('survives a half-deleted fence rather than appending underneath it', () => {
     const damaged = `${theirs}\n${SPECD_BLOCK_BEGIN}\n\nold rules someone cut the end off\n`;
-    const merged = mergeAgentsMd(damaged, generated);
+    const merged = mergeAgentsMd(damaged, generated, supplement);
 
     expect(merged).not.toContain('old rules someone cut the end off');
     expect(merged).toContain('Never touch `legacy/` without asking Priya.');
@@ -83,7 +113,7 @@ describe('mergeAgentsMd', () => {
     // Nobody's writing is discarded here, so there is nothing to preserve —
     // and fencing specd's own output inside specd's own output reads as two
     // sets of rules where there is one.
-    const merged = mergeAgentsMd(generated, generated);
+    const merged = mergeAgentsMd(generated, generated, supplement);
     expect(merged).toBe(generated);
     expect(merged).not.toContain(SPECD_BLOCK_BEGIN);
   });
diff --git a/packages/templates/src/agents-md.ts b/packages/templates/src/agents-md.ts
index 797fca1..91ebc85 100644
--- a/packages/templates/src/agents-md.ts
+++ b/packages/templates/src/agents-md.ts
@@ -93,6 +93,61 @@ spec_status · spec_pull · list_specs
 `;
 }
 
+/**
+ * What specd adds to a repository that already has working agreements.
+ *
+ * The full `renderAgentsMd` document is a complete set of engineering rules —
+ * read the docs first, cite what you relied on, update them in the same PR —
+ * and a team that has written its own AGENTS.md has usually said most of that
+ * already, in its own words. Appending the whole thing under theirs produced
+ * two statements of the same practice, which is worse than either: an agent
+ * follows whichever it reads first, and a reader cannot tell which is current.
+ *
+ * So when there is an existing file, specd contributes only what is *its*:
+ * the four things its machinery actually enforces, and where the knowledge base
+ * lives. Everything general is left to the team, because they already said it
+ * and it is their repository.
+ */
+export function renderAgentsSupplement(input: {
+  isPrimary: boolean;
+  projectName: string;
+}): string {
+  const { isPrimary, projectName } = input;
+  const asBuiltHome = isPrimary ? 'this repo' : `the primary repo of ${projectName}`;
+
+  return `## specd — added by setup
+
+This repository is spec-driven with [specd](https://github.com/unitypark/specd).
+**The agreements above still stand.** What follows is only the part specd's own
+machinery depends on — where the two overlap, yours win and this block is the
+one to correct.
+
+1. **Work arrives as an approved spec.** Fetch it with \`specd spec pull <id>\`.
+   The server refuses to serve a spec no human has approved, so this is not a
+   convention you can route around.
+2. **Branch \`spec/<ID>-<slug>\`, and title the pull request \`[<ID>] - <Title>\`.**
+   The merge webhook matches that shape back to the spec; a branch named
+   anything else is delivered work specd cannot record.
+3. **The last task of a spec files its as-built copy** to
+   \`knowledge/specs/<ID>-<slug>.md\` in ${asBuiltHome}. That record is what
+   grounds the next spec.
+4. **The knowledge base is \`knowledge/\`**, and it is what specs get drafted
+   and cited from. Start at [knowledge/README.md](knowledge/README.md); specd
+   re-indexes the directory whenever a change to it merges.
+
+## Wiring the knowledge tools
+
+Point any MCP-capable editor at specd. It serves this project's knowledge base
+and its approved specs, read-only — approval stays a signed-in human in the app.
+
+    { "mcpServers": { "specd": { "command": "specd", "args": ["mcp", "serve"] } } }
+
+Needs the specd CLI on your PATH and \`specd login\` once per machine.
+Tools: search_knowledge · get_doc · verify_citation · knowledge_health ·
+spec_status · spec_pull · list_specs
+`;
+}
+
 export function renderClaudeMd(): string {
   return `# CLAUDE.md
 
@@ -137,7 +192,16 @@ const GENERATED_HEADING = '# Working agreements for AI agents (generated by spec
  *   3. Anything else is a team's own file. It survives verbatim, and the
  *      generated rules land underneath it, fenced and labelled.
  */
-export function mergeAgentsMd(existing: string | null | undefined, generated: string): string {
+export function mergeAgentsMd(
+  existing: string | null | undefined,
+  generated: string,
+  /**
+   * What to append when the repository already has agreements. Falls back to
+   * the whole document, which is what this used to do unconditionally and is
+   * still right when there is nothing to duplicate.
+   */
+  supplement?: string,
+): string {
   const current = (existing ?? '').trim();
   if (!current) return generated;
 
@@ -147,11 +211,7 @@ export function mergeAgentsMd(existing: string | null | undefined, generated: st
   // actually sees, and they are the half that says which rules are whose.
   const block =
     `${SPECD_BLOCK_BEGIN}\n\n` +
-    '## Working agreements added by specd\n\n' +
-    '_Generated by a setup run, and yours to edit. Your own rules above came\n' +
-    'first: where the two disagree, they win and this block is the thing to\n' +
-    'correct._\n\n' +
-    `${stripHeading(generated)}\n${SPECD_BLOCK_END}\n`;
+    `${stripHeading(supplement ?? generated)}\n${SPECD_BLOCK_END}\n`;
 
   const replaced = replaceFencedBlock(current, block);
   if (replaced) return replaced;
diff --git a/packages/templates/src/knowledge.ts b/packages/templates/src/knowledge.ts
index 8ce724a..c87398c 100644
--- a/packages/templates/src/knowledge.ts
+++ b/packages/templates/src/knowledge.ts
@@ -1,5 +1,5 @@
 import { type DetectedStack, describeStack } from './stack.js';
-import { mergeAgentsMd, mergeClaudeMd } from './agents-md.js';
+import { mergeAgentsMd, mergeClaudeMd, renderAgentsSupplement } from './agents-md.js';
 import {
   hasDataEvidence,
   hasIntegrationEvidence,
@@ -634,8 +634,8 @@ export function renderOpenQuestions(input: DocContext): string {
   const merged = mergedAgentDocs(evidence);
   if (merged.length) {
     items.push({
-      question: `This repo already had ${merged.join(' and ')} — read ${merged.length === 1 ? 'it' : 'them'} against the specd block appended below yours and reconcile anything that disagrees.`,
-      why: "Your rules were kept and specd's were added under a marked fence, so nothing was lost — but two rules that contradict each other are worse than either alone: an agent follows whichever it reads first.",
+      question: `This repo already had ${merged.join(' and ')} — check the short specd block appended below yours does not contradict what you already say.`,
+      why: "Your rules were kept untouched, and specd appended only the four things its own machinery enforces rather than a second set of engineering rules. Anything the two do both mention, yours wins — but only a human can say which is which.",
       doc: 'conventions.md',
     });
   }
@@ -1005,7 +1005,13 @@ export function renderScaffold(input: {
   const docs = scaffoldDocPaths(evidence);
   const ctx: DocContext = { repoName, projectName, stack, evidence, drafted, docs };
 
-  const mergedAgents = mergeAgentsMd(existing?.agentsMd, agentsMd);
+  // A repository with its own agreements gets the short specd-specific block,
+  // not the whole document — see `renderAgentsSupplement`.
+  const mergedAgents = mergeAgentsMd(
+    existing?.agentsMd,
+    agentsMd,
+    renderAgentsSupplement({ isPrimary: input.isPrimary, projectName }),
+  );
   const mergedClaude = mergeClaudeMd(existing?.claudeMd);
 
   const files: ScaffoldFile[] = [
@@ -1077,7 +1083,7 @@ export function renderSetupPrBody(input: {
         merged.length === 1 ? 'was' : 'were'
       } kept.** Nothing in ${
         merged.length === 1 ? 'it' : 'them'
-      } was rewritten — specd's agreements are appended below yours, fenced by\n> \`<!-- specd:begin -->\` markers so a later setup run updates only that block.\n> Where the two sets disagree, yours came first and a human decides.`
+      } was rewritten. specd appended a short block — the four rules its own\n> machinery enforces, and where the knowledge base lives — rather than a second\n> set of engineering rules on top of yours. It is fenced by\n> \`<!-- specd:begin -->\` markers, so a later setup run updates only that block.`
     : '';
 
   return `## specd setup — review me, then merge to adopt