diff --git a/.gitignore b/.gitignore
index bbff391..17e657d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -52,8 +52,8 @@ dist/
 downloads/
 eggs/
 .eggs/
-lib/
-lib64/
+/lib/
+/lib64/
 parts/
 sdist/
 var/
diff --git a/talent-builder/src/lib/codec.ts b/talent-builder/src/lib/codec.ts
new file mode 100644
index 0000000..a4b2887
--- /dev/null
+++ b/talent-builder/src/lib/codec.ts
@@ -0,0 +1,81 @@
+import type { GridSpec } from "./types";
+
+// Build format: `${class}.${tree0}.${tree1}.${tree2}`
+// Compact URL-safe format using base36: encode non-zero talents as "index_rank" pairs separated by underscores
+// Example: "0_3_b_5" means slot 0 has rank 3, slot 11 (b in base36) has rank 5
+// For ranks: 1-9 are literal, 10+ use base36 (a=10, b=11, etc)
+// For indices: use base36 notation
+
+const BASE36_CHARS = "0123456789abcdefghijklmnopqrstuvwxyz";
+
+function encodeRank(rank: number): string {
+  if (rank < 10) return String(rank);
+  return BASE36_CHARS[rank] || "0";
+}
+
+function decodeRank(char: string): number {
+  const idx = BASE36_CHARS.indexOf(char.toLowerCase());
+  return idx >= 0 ? idx : 0;
+}
+
+export function encodeBuild(spec: GridSpec): string {
+  const parts = spec.trees.map((t) => {
+    const pairs: string[] = [];
+    t.slots.forEach((s, idx) => {
+      if (s.talent && s.talent.currentRank > 0) {
+        // Encode as index_rank using base36 for both
+        const idxStr = idx.toString(36);
+        const rankStr = encodeRank(s.talent.currentRank);
+        pairs.push(idxStr + rankStr);
+      }
+    });
+    return pairs.join("_");
+  });
+  return `${spec.className}.${parts.join(".")}`;
+}
+
+export function decodeBuild(spec: GridSpec, build: string): GridSpec {
+  const parts = build.split(".");
+  if (parts.length < 2) return spec;
+
+  const cls = parts[0];
+  const out = structuredClone(spec);
+  out.className = cls || spec.className;
+
+  // Parse each tree (parts[1], parts[2], parts[3])
+  out.trees.forEach((t, ti) => {
+    const treeStr = parts[ti + 1] || "";
+    if (!treeStr) return;
+
+    // Split by underscore to get index-rank pairs
+    const pairs = treeStr.split("_");
+    for (const pair of pairs) {
+      if (pair.length < 2) continue;
+
+      // Last character is rank, everything before is index
+      const rankChar = pair[pair.length - 1];
+      const idxStr = pair.substring(0, pair.length - 1);
+
+      const idx = parseInt(idxStr, 36);
+      const rank = decodeRank(rankChar);
+
+      if (!Number.isFinite(idx) || !Number.isFinite(rank)) continue;
+      if (idx < 0 || idx >= t.slots.length) continue;
+
+      const slot = t.slots[idx];
+      if (slot.talent) {
+        slot.talent.currentRank = clamp(rank, 0, slot.talent.maxRank);
+      }
+    }
+  });
+  return out;
+}
+
+function clampDigit(n: number): number {
+  if (!Number.isFinite(n)) return 0;
+  return Math.max(0, Math.min(9, Math.trunc(n)));
+}
+
+function clamp(n: number, min: number, max: number): number {
+  return Math.max(min, Math.min(max, n));
+}
diff --git a/talent-builder/src/lib/transform.ts b/talent-builder/src/lib/transform.ts
new file mode 100644
index 0000000..4a575d7
--- /dev/null
+++ b/talent-builder/src/lib/transform.ts
@@ -0,0 +1,66 @@
+import type { AscClassTalents, GridSpec, GridTree, GridSlot, AscTalent } from "./types";
+
+function toIndex(tier: number, column: number): number {
+  return (tier - 1) * 4 + (column - 1);
+}
+
+export function iconTextureToFilename(iconTexture: string): string {
+  // Input examples:
+  //  - "Interface\\Icons\\Spell_Fire_SoulBurn"
+  //  - "Interface/Icons/Spell_Fire_SoulBurn.blp"
+  //  - " spell_fire_soulburn "
+  const normalized = (iconTexture || "").trim().replace(/\\/g, "/");
+  const parts = normalized.split("/");
+  let base = (parts[parts.length - 1] || normalized).trim();
+  // Strip any extension if present
+  base = base.replace(/\.(blp|png|jpg|jpeg)$/i, "");
+  const filename = base.toLowerCase() + ".png";
+
+  // Determine subdirectory based on filename prefix
+  // Icons are organized in: spells/, items/, professions/, classes/, talents/, ui/, misc/, raids/
+  if (filename.startsWith("spell_") || filename.startsWith("ability_")) {
+    return "spells/" + filename;
+  } else if (filename.startsWith("inv_")) {
+    return "items/" + filename;
+  } else if (filename.startsWith("trade_")) {
+    return "professions/" + filename;
+  } else if (filename.startsWith("achievement_")) {
+    return "ui/" + filename;
+  } else {
+    // Default to spells for unknown prefixes
+    return "spells/" + filename;
+  }
+}
+
+function buildEmptySlots(): GridSlot[] {
+  const slots: GridSlot[] = [];
+  for (let row = 0; row < 11; row++) {
+    for (let col = 0; col < 4; col++) {
+      const index = row * 4 + col;
+      slots.push({ index, row, col, talent: null });
+    }
+  }
+  return slots;
+}
+
+function placeTalents(slots: GridSlot[], talents: AscTalent[]): void {
+  for (const t of talents) {
+    const idx = toIndex(t.tier, t.column);
+    const slot = slots[idx];
+    if (!slot) continue;
+    slot.talent = t;
+  }
+}
+
+export function toGridSpec(className: string, data: AscClassTalents): GridSpec {
+  const trees: GridTree[] = Object.keys(data)
+    .sort((a, b) => (data[a].tabIndex ?? 0) - (data[b].tabIndex ?? 0))
+    .map((name) => {
+      const tree = data[name];
+      const slots = buildEmptySlots();
+      placeTalents(slots, tree.talents);
+      return { name, slots } as GridTree;
+    });
+
+  return { className, trees };
+}
diff --git a/talent-builder/src/lib/types.ts b/talent-builder/src/lib/types.ts
new file mode 100644
index 0000000..713d869
--- /dev/null
+++ b/talent-builder/src/lib/types.ts
@@ -0,0 +1,36 @@
+export type AscTalent = {
+  name: string;
+  spellId: number;
+  iconTexture: string; // e.g., Interface\\Icons\\Spell_Fire_FlameBolt
+  tier: number; // 1..11
+  column: number; // 1..4
+  maxRank: number;
+  currentRank: number;
+  tooltip: string;
+  requires?: number | null; // optional: index or spellId of prerequisite
+};
+
+export type AscTree = {
+  tabIndex: number;
+  pointsSpent?: number;
+  talents: AscTalent[];
+};
+
+export type AscClassTalents = Record<string, AscTree>; // keys: Fire/Frost/Arcane etc.
+
+export type GridSlot = {
+  index: number; // 0..43 in 4x11
+  row: number; // 0..10
+  col: number; // 0..3
+  talent: AscTalent | null;
+};
+
+export type GridTree = {
+  name: string; // Fire/Frost/Arcane
+  slots: GridSlot[]; // 44 items
+};
+
+export type GridSpec = {
+  className: string; // mage, warrior, etc.
+  trees: GridTree[]; // length 3
+};