diff --git a/src/utils/sku.js b/src/utils/sku.js
index 5dd0bda..8182a74 100644
--- a/src/utils/sku.js
+++ b/src/utils/sku.js
@@ -10,6 +10,13 @@ function fnv1a32(str) {
   return (h >>> 0).toString(16).padStart(8, "0");
 }
 
+function idToCspc6(idDigits) {
+  const s = String(idDigits || "").trim();
+  if (!/^\d{1,6}$/.test(s)) return "";
+  return s.padStart(6, "0");
+}
+  
+
 function normalizeCspc(v) {
   const m = String(v ?? "").match(/\b(\d{6})\b/);
   return m ? m[1] : "";
@@ -84,7 +91,9 @@ function normalizeSkuKey(v, { storeLabel, url } = {}) {
   }
   if (/^id:/i.test(raw)) {
     const id = normalizeIdDigits(raw);
-    return id ? `id:${id}` : "";
+    if (!id) return "";
+    const cspc = idToCspc6(id);
+    return cspc ? cspc : `id:${id}`;
   }
 
   if (raw.startsWith("u:")) return raw;
diff --git a/src/utils/sku_map.js b/src/utils/sku_map.js
index 9385725..7596af0 100644
--- a/src/utils/sku_map.js
+++ b/src/utils/sku_map.js
@@ -135,6 +135,13 @@ function findSkuLinksFile({ dbDir, mappingFile } = {}) {
   return "";
 }
 
+function normalizeImplicitSkuKey(k) {
+  const s = String(k || "").trim();
+  const m = s.match(/^id:(\d{1,6})$/i);
+  if (m) return String(m[1]).padStart(6, "0");
+  return s;
+}
+
 /* ---------------- Public API ---------------- */
 
 function buildSkuMapFromLinksArray(links) {
@@ -142,8 +149,8 @@ function buildSkuMapFromLinksArray(links) {
   const all = new Set();
 
   for (const x of Array.isArray(links) ? links : []) {
-    const a = String(x?.fromSku || "").trim();
-    const b = String(x?.toSku || "").trim();
+    const a = normalizeImplicitSkuKey(x?.fromSku);
+    const b = normalizeImplicitSkuKey(x?.toSku);
     if (!a || !b) continue;
 
     all.add(a);
@@ -179,7 +186,7 @@ function buildSkuMapFromLinksArray(links) {
   }
 
   function canonicalSku(sku) {
-    const s = String(sku || "").trim();
+    const s = normalizeImplicitSkuKey(sku);
     if (!s) return s;
     return canonBySku.get(s) || s;
   }
diff --git a/tools/dedupe_skulinks.js b/tools/dedupe_skulinks.js
index f23a813..7dbca67 100644
--- a/tools/dedupe_skulinks.js
+++ b/tools/dedupe_skulinks.js
@@ -1,4 +1,5 @@
 #!/usr/bin/env node
+"use strict";
 
 const fs = require("fs");
 const path = require("path");
@@ -6,7 +7,14 @@ const path = require("path");
 const DB_DIR = path.join(__dirname, "../data/db");
 const LINKS_FILE = path.join(__dirname, "../data/sku_links.json");
 
-// collect all valid SKUs from db files
+function normalizeImplicitSkuKey(k) {
+  const s = String(k || "").trim();
+  const m = s.match(/^id:(\d{1,6})$/i);
+  if (m) return String(m[1]).padStart(6, "0");
+  return s;
+}
+
+// collect all valid SKUs from db files (normalized)
 const validSkus = new Set();
 
 for (const file of fs.readdirSync(DB_DIR)) {
@@ -14,26 +22,63 @@ for (const file of fs.readdirSync(DB_DIR)) {
   const data = JSON.parse(fs.readFileSync(path.join(DB_DIR, file), "utf8"));
   if (!Array.isArray(data.items)) continue;
   for (const item of data.items) {
-    if (item.sku) validSkus.add(String(item.sku));
+    if (!item || !item.sku) continue;
+    const k = normalizeImplicitSkuKey(item.sku);
+    if (k) validSkus.add(k);
   }
 }
 
 // load links
 const linksData = JSON.parse(fs.readFileSync(LINKS_FILE, "utf8"));
-const originalCount = linksData.links.length;
+const originalCount = Array.isArray(linksData.links) ? linksData.links.length : 0;
 
-// keep only links where BOTH skus exist
-linksData.links = linksData.links.filter(
-  ({ fromSku, toSku }) =>
-    validSkus.has(String(fromSku)) && validSkus.has(String(toSku))
-);
+let prunedMissing = 0;
+let prunedAuto = 0;
+let prunedDup = 0;
+
+const seen = new Set(); // dedupe after normalization
+
+const nextLinks = [];
+for (const x of Array.isArray(linksData.links) ? linksData.links : []) {
+  const a = normalizeImplicitSkuKey(x?.fromSku);
+  const b = normalizeImplicitSkuKey(x?.toSku);
+  if (!a || !b) {
+    prunedMissing++;
+    continue;
+  }
+
+  // drop links that are now implicit (id:1234 <-> 001234 etc)
+  if (a === b) {
+    prunedAuto++;
+    continue;
+  }
+
+  // keep only links where BOTH normalized skus exist in db
+  if (!validSkus.has(a) || !validSkus.has(b)) {
+    prunedMissing++;
+    continue;
+  }
+
+  // dedupe (undirected) after normalization
+  const key = a < b ? `${a}|${b}` : `${b}|${a}`;
+  if (seen.has(key)) {
+    prunedDup++;
+    continue;
+  }
+  seen.add(key);
+
+  nextLinks.push({ fromSku: a, toSku: b });
+}
+
+linksData.links = nextLinks;
 
 // write back in place
-fs.writeFileSync(
-  LINKS_FILE,
-  JSON.stringify(linksData, null, 2) + "\n"
-);
+fs.writeFileSync(LINKS_FILE, JSON.stringify(linksData, null, 2) + "\n");
 
-console.log(
-  `Pruned ${originalCount - linksData.links.length} invalid links`
-);
+const totalPruned = originalCount - linksData.links.length;
+
+console.log(`Pruned ${totalPruned} total links`);
+console.log(`- ${prunedAuto} now-implicit (id:<1-6> ↔ CSPC)`);
+console.log(`- ${prunedMissing} missing/invalid vs db`);
+console.log(`- ${prunedDup} duplicates after normalization`);
+console.log(`Remaining ${linksData.links.length}`);
diff --git a/viz/app/mapping.js b/viz/app/mapping.js
index 0781078..cfefdb5 100644
--- a/viz/app/mapping.js
+++ b/viz/app/mapping.js
@@ -8,9 +8,16 @@ export function clearSkuRulesCache() {
   CACHED = null;
 }
 
+function normalizeImplicitSkuKey(k) {
+  const s = String(k || "").trim();
+  const m = s.match(/^id:(\d{1,6})$/i);
+  if (m) return String(m[1]).padStart(6, "0");
+  return s;
+}
+
 function canonicalPairKey(a, b) {
-  const x = String(a || "");
-  const y = String(b || "");
+  const x = normalizeImplicitSkuKey(a);
+  const y = normalizeImplicitSkuKey(b);
   if (!x || !y) return "";
   return x < y ? `${x}|${y}` : `${y}|${x}`;
 }
@@ -19,8 +26,8 @@ function buildForwardMap(links) {
   // Keep this for reference/debug; grouping no longer depends on direction.
   const m = new Map();
   for (const x of Array.isArray(links) ? links : []) {
-    const fromSku = String(x?.fromSku || "").trim();
-    const toSku = String(x?.toSku || "").trim();
+    const fromSku = normalizeImplicitSkuKey(x?.fromSku);
+    const toSku = normalizeImplicitSkuKey(x?.toSku);
     if (fromSku && toSku && fromSku !== toSku) m.set(fromSku, toSku);
   }
   return m;
@@ -120,8 +127,8 @@ function buildGroupsAndCanonicalMap(links) {
   const all = new Set();
 
   for (const x of Array.isArray(links) ? links : []) {
-    const a = String(x?.fromSku || "").trim();
-    const b = String(x?.toSku || "").trim();
+    const a = normalizeImplicitSkuKey(x?.fromSku);
+    const b = normalizeImplicitSkuKey(x?.toSku);
     if (!a || !b) continue;
     all.add(a);
     all.add(b);
@@ -187,7 +194,7 @@ export async function loadSkuRules() {
   const ignoreSet = buildIgnoreSet(ignores);
 
   function canonicalSku(sku) {
-    const s = String(sku || "").trim();
+    const s = normalizeImplicitSkuKey(sku);
     if (!s) return s;
     return canonBySku.get(s) || s;
   }
diff --git a/viz/app/sku.js b/viz/app/sku.js
index 4dcdf8a..4c0ef54 100644
--- a/viz/app/sku.js
+++ b/viz/app/sku.js
@@ -21,8 +21,12 @@ export function parsePriceToNumber(v) {
   }
   
   export function keySkuForRow(r) {
-    const real = String(r?.sku || "").trim();
-    return real ? real : makeSyntheticSku(r);
+    const real0 = String(r?.sku || "").trim();
+    if (real0) {
+      const m = real0.match(/^id:(\d{1,6})$/i);
+      return m ? String(m[1]).padStart(6, "0") : real0;
+    }
+    return makeSyntheticSku(r);
   }
   
   export function displaySku(key) {