diff --git a/packages/viewer/e2e/overlap-baseline.json b/packages/viewer/e2e/overlap-baseline.json
new file mode 100644
index 0000000..1cacc00
--- /dev/null
+++ b/packages/viewer/e2e/overlap-baseline.json
@@ -0,0 +1,26 @@
+{
+  "_comment": [
+    "Known-failing boards for the rendered-geometry overlap guard. Every board NOT listed here must",
+    "render clean; a new name appearing in a run is a regression and fails CI. This exists because the",
+    "guard had been red on master since the SGCR migration, which meant it gated nothing at all — three",
+    "PRs merged on top of a red guard without anyone being able to tell whether they made it worse.",
+    "",
+    "Entries are board-level, not violation-level, on purpose: the exact node ids differ between macOS",
+    "and Linux CI (text metrics move the layout), so pinning ids would fail constantly off-CI. The",
+    "`observed` lists are documentation of what CI saw when the entry was added, not an assertion —",
+    "read them when a listed board changes to judge whether it got better or worse.",
+    "",
+    "This list is a debt ledger and should only ever shrink. Delete a board the moment it renders clean",
+    "on CI; the guard prints a reminder when a listed board passes."
+  ],
+  "_source": "CI run 31290712587 (master @ fb6ff4a, ubuntu-latest)",
+  "known_failing": {
+    "ex_architecture-zones": { "observed": ["node-node:web|bff", "edge-over-node:worker"] },
+    "ex_data-lineage": { "observed": ["edge-over-node:events"] },
+    "ex_dataeng-etl": { "observed": ["edge-over-node:kafka"] },
+    "ex_k8s-topology": { "observed": ["edge-over-node:ingress,cm"] },
+    "ex_support-escalation": { "observed": ["edge-over-node:created,triage,l2inv"] },
+    "ex_swimlane": { "observed": ["edge-over-node:checkout"] },
+    "syn_groups_long": { "observed": ["edge-over-node:a1,a2"] }
+  }
+}
diff --git a/packages/viewer/e2e/overlap.e2e.mjs b/packages/viewer/e2e/overlap.e2e.mjs
index 4ce0837..1e169db 100644
--- a/packages/viewer/e2e/overlap.e2e.mjs
+++ b/packages/viewer/e2e/overlap.e2e.mjs
@@ -5,8 +5,13 @@
 // stressors, each rendered twice to prove the layout is deterministic (not flaky).
 //
 //   npm run test:overlap        (build first)  |  test:overlap:nobuild (dist already built)
-// Exit 0 = all clean + deterministic, 1 = a failure. The deliberately-pathological topologies
-// (skip-rank edges, cycles, self-loops) live in the one-off measurement harness, not here.
+// The deliberately-pathological topologies (skip-rank edges, cycles, self-loops) live in the
+// one-off measurement harness, not here.
+//
+// Boards listed in overlap-baseline.json are known-bad and don't fail the build; everything else
+// must render clean. Exit 0 = no board outside the baseline broke, 1 = a regression. Violations are
+// always printed in full, baselined or not, so a known-bad board getting WORSE is visible in review
+// even though it doesn't flip the exit code.
 import { chromium } from "playwright";
 import { spawn } from "node:child_process";
 import { readFileSync, readdirSync } from "node:fs";
@@ -22,6 +27,10 @@ const BASE = `http://127.0.0.1:${PORT}`;
 const WSID = "overlap";
 const U = `${BASE}/w/${WSID}/`;
 const RUNS = 2; // each case rendered twice → determinism check
+// Boards already known to render with overlaps. They still run and still print their violations;
+// they just don't fail the build. Anything NOT listed must be clean. See the file's own _comment.
+const BASELINE_REL = "e2e/overlap-baseline.json";
+const BASELINE = JSON.parse(readFileSync(join(HERE, "overlap-baseline.json"), "utf8")).known_failing;
 
 const lbl = (s) => ({ data: { label: s } });
 // A few CLEAN stressors (the risk areas: long labels in zones, swimlanes, wide fan-out).
@@ -75,7 +84,8 @@ const push = (a, t, c) => fetch(`${U}push`, { method: "POST", headers: { "conten
 
 const srv = spawn("node", [join(VIEWER, "dist", "server.js")], { env: { ...process.env, PORT: String(PORT), PUSH_TOKEN: TOKEN }, stdio: ["ignore", "ignore", "inherit"] });
 let browser;
-const fails = [];
+const fails = [];   // boards that broke and are NOT in the baseline → CI failure
+const fixed = [];   // boards in the baseline that now render clean → prompt to shrink the ledger
 try {
   await waitUp();
   for (const c of cases) { const r = await push(c.name, c.type, c.content); if (!r.ok) throw new Error(`push ${c.name} -> ${r.status}`); }
@@ -98,13 +108,22 @@ try {
     }
     const m = runs[0];
     const issues = [];
-    if (m.nn.length) issues.push(`node-node:${m.nn.slice(0, 3).join(",")}`);
-    if (m.cc.length) issues.push(`container:${m.cc.slice(0, 3).join(",")}`);
-    if (m.sp.length) issues.push(`spillout:${m.sp.slice(0, 3).join(",")}`);
-    if (m.en.length) issues.push(`edge-over-node:${m.en.slice(0, 3).join(",")}`);
-    if (!runs.every((r) => r.sig === m.sig)) issues.push("FLAKY (geometry differs across runs)");
-    const ok = issues.length === 0;
-    console.log(`${ok ? "PASS" : "FAIL"}  ${c.name}  (leaves=${m.leaves})${ok ? "" : "  → " + issues.join("; ")}`);
+    // Full lists, not the first 3: when a known-failing board changes, the detail is the only way
+    // to tell "same breakage" from "got worse", and a truncated list hides the difference.
+    if (m.nn.length) issues.push(`node-node:${m.nn.join(",")}`);
+    if (m.cc.length) issues.push(`container:${m.cc.join(",")}`);
+    if (m.sp.length) issues.push(`spillout:${m.sp.join(",")}`);
+    if (m.en.length) issues.push(`edge-over-node:${m.en.join(",")}`);
+    const flaky = !runs.every((r) => r.sig === m.sig);
+    if (flaky) issues.push("FLAKY (geometry differs across runs)");
+    const clean = issues.length === 0;
+    const baselined = Object.hasOwn(BASELINE, c.name);
+    // Flakiness is never excusable: a baseline entry records a bad-but-STABLE layout, and a board
+    // whose geometry moves between runs can't be reasoned about at all.
+    const ok = clean || (baselined && !flaky);
+    const tag = clean ? (baselined ? "FIXED" : "PASS") : ok ? "KNOWN" : "FAIL";
+    console.log(`${tag}  ${c.name}  (leaves=${m.leaves})${clean ? "" : "  → " + issues.join("; ")}`);
+    if (clean && baselined) fixed.push(c.name);
     if (!ok) fails.push(c.name);
   }
 } catch (e) {
@@ -114,5 +133,15 @@ try {
   if (browser) await browser.close();
   srv.kill("SIGTERM");
 }
-console.log(`\n=== ${cases.length - fails.length}/${cases.length} clean & deterministic ===`);
+const knownCount = cases.filter((c) => Object.hasOwn(BASELINE, c.name)).length - fixed.length;
+console.log(`\n=== ${cases.length - fails.length - knownCount}/${cases.length} clean, ${knownCount} known-bad, ${fails.length} regressed ===`);
+if (fixed.length) {
+  console.log(`\n${fixed.length} board(s) now render clean: ${fixed.join(", ")}`);
+  console.log(`Remove them from ${BASELINE_REL} so they stay fixed — the ledger only shrinks.`);
+}
+if (fails.length) {
+  console.log(`\nREGRESSED (not in the baseline): ${fails.join(", ")}`);
+  console.log(`These boards are expected to render with zero overlaps. Fix the layout, or — if this`);
+  console.log(`is a deliberate, reviewed trade — add the board to ${BASELINE_REL} with a reason.`);
+}
 process.exit(fails.length ? 1 : 0);