bun.lock

@@ -30,6 +30,7 @@
       "dependencies": {
         "ajv": "^8.20.0",
         "cborg": "^4.2.3",
+        "liquidjs": "^10.27.0",
         "xxhash-wasm": "^1.1.0",
       },
     },
@@ -141,6 +142,8 @@
 
     "chardet": ["chardet@2.1.1", "", {}, "sha512-PsezH1rqdV9VvyNhxxOW32/d75r01NY7TQCmOqomRo15ZSOKbpTFVsfjghxo6JloQUCGnH4k1LGu0R4yCLlWQQ=="],
 
+    "commander": ["commander@10.0.1", "", {}, "sha512-y4Mg2tXshplEbSGzx7amzPwKKOCGuoSRP/CjEdwwk0FOGlUbq6lKuoyDZTNZkmxHdJtp54hdfY/JUrdL7Xfdug=="],
+
     "cross-spawn": ["cross-spawn@7.0.6", "", { "dependencies": { "path-key": "^3.1.0", "shebang-command": "^2.0.0", "which": "^2.0.1" } }, "sha512-uV2QOWP2nWzsy2aMp8aRibhi9dlzF5Hgh5SHaB9OiTGEyDTiJJyx0uy51QXdyWbtAHNua4XJzUKca3OzKUd3vA=="],
 
     "dataloader": ["dataloader@1.4.0", "", {}, "sha512-68s5jYdlvasItOJnCuI2Q9s4q98g0pCyL3HrcKJu8KNugUl8ahgmZYg38ysLTgQjjXX3H8CJLkAvWrclWfcalw=="],
@@ -203,6 +206,8 @@
 
     "layerr": ["layerr@3.0.0", "", {}, "sha512-tv754Ki2dXpPVApOrjTyRo4/QegVb9eVFq4mjqp4+NM5NaX7syQvN5BBNfV/ZpAHCEHV24XdUVrBAoka4jt3pA=="],
 
+    "liquidjs": ["liquidjs@10.27.0", "", { "dependencies": { "commander": "^10.0.0" }, "bin": { "liquidjs": "bin/liquid.js", "liquid": "bin/liquid.js" } }, "sha512-tw/OA59K7aIBlMKIrKlumr37fiZUheShVHXY8cVctWisgY1p9mc5hreOvlreoS0wTiwlWk14Ya7305c2a/Cg5w=="],
+
     "locate-path": ["locate-path@5.0.0", "", { "dependencies": { "p-locate": "^4.1.0" } }, "sha512-t7hw9pI+WvuwNJXwk5zVHpyhIqzg2qTlklJOf0mVxGSbe3Fp2VieZcduNYjaLDoy6p9uGpQEGWG87WpMKlNq8g=="],
 
     "lodash.startcase": ["lodash.startcase@4.4.0", "", {}, "sha512-+WKqsK294HMSc2jEbNgpHpd0JfIBhp7rEV4aqXWqFr6AlXov+SlcgB1Fv01y2kGe3Gc8nMW7VA0SrGuSkRfIEg=="],

packages/cli-json-cas/src/cli.test.ts

@@ -314,3 +314,286 @@ describe("ucas render command", () => {
     }
   });
 });
+
+describe("Suite 6: CLI Integration with Templates", () => {
+  test("6.1 CLI with Template (Default Parameters)", async () => {
+    const tmpStore = mkdtempSync(join(tmpdir(), "json-cas-test-"));
+    try {
+      // Initialize store
+      await runCli(["init"], tmpStore);
+
+      // Create schema
+      const schemaFile = join(tmpStore, "schema.json");
+      writeFileSync(
+        schemaFile,
+        JSON.stringify({
+          type: "object",
+          properties: { name: { type: "string" } },
+        }),
+      );
+      const { stdout: schemaHash } = await runCli(
+        ["schema", "put", schemaFile],
+        tmpStore,
+      );
+
+      // Create node
+      const nodeFile = join(tmpStore, "node.json");
+      writeFileSync(nodeFile, JSON.stringify({ name: "Alice" }));
+      const { stdout: nodeHash } = await runCli(
+        ["put", schemaHash.trim(), nodeFile],
+        tmpStore,
+      );
+
+      // Create template file (JSON-encoded string)
+      const templateFile = join(tmpStore, "template.json");
+      writeFileSync(templateFile, JSON.stringify("Hello {{ payload.name }}!"));
+      const { stdout: tmplHash } = await runCli(
+        ["put", "@string", templateFile],
+        tmpStore,
+      );
+
+      // Register template
+      await runCli(
+        [
+          "var",
+          "set",
+          `@ucas/template/text/${schemaHash.trim()}`,
+          tmplHash.trim(),
+        ],
+        tmpStore,
+      );
+
+      // Render with template
+      const { stdout: output, exitCode } = await runCli(
+        ["render", nodeHash.trim()],
+        tmpStore,
+      );
+
+      expect(exitCode).toBe(0);
+      expect(output).toBe("Hello Alice!");
+    } finally {
+      rmSync(tmpStore, { recursive: true, force: true });
+    }
+  });
+
+  test("6.2 CLI with Template + Custom Decay", async () => {
+    const tmpStore = mkdtempSync(join(tmpdir(), "json-cas-test-"));
+    try {
+      await runCli(["init"], tmpStore);
+
+      // Create schema with child ref
+      const schemaFile = join(tmpStore, "schema.json");
+      writeFileSync(
+        schemaFile,
+        JSON.stringify({
+          type: "object",
+          properties: {
+            value: { type: "string" },
+            child: {
+              anyOf: [{ type: "string", format: "cas_ref" }, { type: "null" }],
+            },
+          },
+        }),
+      );
+      const { stdout: schemaHash } = await runCli(
+        ["schema", "put", schemaFile],
+        tmpStore,
+      );
+
+      // Create child node
+      const childFile = join(tmpStore, "child.json");
+      writeFileSync(childFile, JSON.stringify({ value: "child", child: null }));
+      const { stdout: childHash } = await runCli(
+        ["put", schemaHash.trim(), childFile],
+        tmpStore,
+      );
+
+      // Create parent node
+      const parentFile = join(tmpStore, "parent.json");
+      writeFileSync(
+        parentFile,
+        JSON.stringify({ value: "parent", child: childHash.trim() }),
+      );
+      const { stdout: parentHash } = await runCli(
+        ["put", schemaHash.trim(), parentFile],
+        tmpStore,
+      );
+
+      // Create template showing resolution (JSON-encoded string)
+      const templateFile = join(tmpStore, "template.json");
+      writeFileSync(
+        templateFile,
+        JSON.stringify("{{ payload.value }}(res={{ resolution }})"),
+      );
+      const { stdout: tmplHash } = await runCli(
+        ["put", "@string", templateFile],
+        tmpStore,
+      );
+
+      // Register template
+      await runCli(
+        [
+          "var",
+          "set",
+          `@ucas/template/text/${schemaHash.trim()}`,
+          tmplHash.trim(),
+        ],
+        tmpStore,
+      );
+
+      // Render with custom decay
+      const { stdout: output, exitCode } = await runCli(
+        ["render", parentHash.trim(), "--decay", "0.7"],
+        tmpStore,
+      );
+
+      expect(exitCode).toBe(0);
+      expect(output).toContain("parent(res=1)");
+    } finally {
+      rmSync(tmpStore, { recursive: true, force: true });
+    }
+  });
+
+  test("6.3 CLI with Template + All Parameters", async () => {
+    const tmpStore = mkdtempSync(join(tmpdir(), "json-cas-test-"));
+    try {
+      await runCli(["init"], tmpStore);
+
+      const schemaFile = join(tmpStore, "schema.json");
+      writeFileSync(
+        schemaFile,
+        JSON.stringify({
+          type: "object",
+          properties: { name: { type: "string" } },
+        }),
+      );
+      const { stdout: schemaHash } = await runCli(
+        ["schema", "put", schemaFile],
+        tmpStore,
+      );
+
+      const nodeFile = join(tmpStore, "node.json");
+      writeFileSync(nodeFile, JSON.stringify({ name: "Bob" }));
+      const { stdout: nodeHash } = await runCli(
+        ["put", schemaHash.trim(), nodeFile],
+        tmpStore,
+      );
+
+      // Create template (JSON-encoded string)
+      const templateFile = join(tmpStore, "template.json");
+      writeFileSync(
+        templateFile,
+        JSON.stringify("Greetings {{ payload.name }}!"),
+      );
+      const { stdout: tmplHash } = await runCli(
+        ["put", "@string", templateFile],
+        tmpStore,
+      );
+
+      await runCli(
+        [
+          "var",
+          "set",
+          `@ucas/template/text/${schemaHash.trim()}`,
+          tmplHash.trim(),
+        ],
+        tmpStore,
+      );
+
+      const { stdout: output, exitCode } = await runCli(
+        [
+          "render",
+          nodeHash.trim(),
+          "--resolution",
+          "0.8",
+          "--decay",
+          "0.6",
+          "--epsilon",
+          "0.005",
+        ],
+        tmpStore,
+      );
+
+      expect(exitCode).toBe(0);
+      expect(output).toBe("Greetings Bob!");
+    } finally {
+      rmSync(tmpStore, { recursive: true, force: true });
+    }
+  });
+
+  test("6.4 CLI with Non-templated Node (YAML Fallback)", async () => {
+    const tmpStore = mkdtempSync(join(tmpdir(), "json-cas-test-"));
+    try {
+      await runCli(["init"], tmpStore);
+
+      const schemaFile = join(tmpStore, "schema.json");
+      writeFileSync(
+        schemaFile,
+        JSON.stringify({
+          type: "object",
+          properties: { name: { type: "string" } },
+        }),
+      );
+      const { stdout: schemaHash } = await runCli(
+        ["schema", "put", schemaFile],
+        tmpStore,
+      );
+
+      const nodeFile = join(tmpStore, "node.json");
+      writeFileSync(nodeFile, JSON.stringify({ name: "Charlie" }));
+      const { stdout: nodeHash } = await runCli(
+        ["put", schemaHash.trim(), nodeFile],
+        tmpStore,
+      );
+
+      // No template registered - should fall back to YAML
+      const { stdout: output, exitCode } = await runCli(
+        ["render", nodeHash.trim()],
+        tmpStore,
+      );
+
+      expect(exitCode).toBe(0);
+      expect(output).toContain("name:");
+      expect(output).toContain("Charlie");
+    } finally {
+      rmSync(tmpStore, { recursive: true, force: true });
+    }
+  });
+
+  test("6.5 CLI Error: Invalid Decay Value", async () => {
+    const tmpStore = mkdtempSync(join(tmpdir(), "json-cas-test-"));
+    try {
+      await runCli(["init"], tmpStore);
+
+      const schemaFile = join(tmpStore, "schema.json");
+      writeFileSync(
+        schemaFile,
+        JSON.stringify({
+          type: "object",
+          properties: { name: { type: "string" } },
+        }),
+      );
+      const { stdout: schemaHash } = await runCli(
+        ["schema", "put", schemaFile],
+        tmpStore,
+      );
+
+      const nodeFile = join(tmpStore, "node.json");
+      writeFileSync(nodeFile, JSON.stringify({ name: "Test" }));
+      const { stdout: nodeHash } = await runCli(
+        ["put", schemaHash.trim(), nodeFile],
+        tmpStore,
+      );
+
+      const { exitCode, stderr } = await runCli(
+        ["render", nodeHash.trim(), "--decay", "1.5"],
+        tmpStore,
+      );
+
+      expect(exitCode).not.toBe(0);
+      expect(stderr).toContain("decay");
+    } finally {
+      rmSync(tmpStore, { recursive: true, force: true });
+    }
+  });
+});

packages/cli-json-cas/src/index.ts

@@ -15,7 +15,7 @@ import {
   InvalidVariableNameError,
   putSchema,
   refs,
-  render,
+  renderAsync,
   TagLabelConflictError,
   VariableNotFoundError,
   validate,
@@ -421,8 +421,14 @@ async function cmdRender(args: string[]): Promise<void> {
   }
 
   try {
-    const output = render(store, hash, { resolution, decay, epsilon });
-    // Output to stdout without JSON wrapping (raw YAML)
+    const varStore = openVarStore();
+    const output = await renderAsync(store, hash, {
+      resolution,
+      decay,
+      epsilon,
+      varStore,
+    });
+    // Output to stdout without JSON wrapping (raw output)
     process.stdout.write(output);
   } catch (error) {
     if (error instanceof Error) {

packages/json-cas/package.json

@@ -21,6 +21,7 @@
   "dependencies": {
     "ajv": "^8.20.0",
     "cborg": "^4.2.3",
+    "liquidjs": "^10.27.0",
     "xxhash-wasm": "^1.1.0"
   }
 }

packages/json-cas/src/index.ts

@@ -4,7 +4,8 @@ export { BOOTSTRAP_STORE } from "./bootstrap-capable.js";
 export { cborEncode } from "./cbor.js";
 export { type GcStats, gc } from "./gc.js";
 export { computeHash, computeSelfHash } from "./hash.js";
-export { type RenderOptions, render } from "./render.js";
+export { renderWithTemplate } from "./liquid-render.js";
+export { type RenderOptions, render, renderAsync } from "./render.js";
 export type { JSONSchema } from "./schema.js";
 export {
   getSchema,

packages/json-cas/src/liquid-render.ts

@@ -0,0 +1,293 @@
+import { type Context, Liquid, type TagToken } from "liquidjs";
+import { putSchema } from "./schema.js";
+import type { Hash, Store } from "./types.js";
+import type { VariableStore } from "./variable-store.js";
+
+export type RenderOptions = {
+  resolution?: number; // (0, 1], default 1.0
+  decay?: number; // (0, 1], default 0.5
+  epsilon?: number; // >= 0, default 0.01
+};
+
+const DEFAULT_RESOLUTION = 1.0;
+const DEFAULT_DECAY = 0.5;
+const DEFAULT_EPSILON = 0.01;
+const FLOAT_TOLERANCE = 1e-10;
+
+/**
+ * Render a CAS node using LiquidJS templates with resolution-based decay.
+ * Templates are discovered via variables: @ucas/template/text/<type-hash>
+ */
+export async function renderWithTemplate(
+  store: Store,
+  varStore: VariableStore,
+  hash: Hash,
+  options?: RenderOptions,
+): Promise<string> {
+  const resolution = options?.resolution ?? DEFAULT_RESOLUTION;
+  const decay = options?.decay ?? DEFAULT_DECAY;
+  const epsilon = options?.epsilon ?? DEFAULT_EPSILON;
+
+  // Validate parameters
+  if (resolution < 0 || resolution > 1) {
+    throw new Error("resolution must be in [0, 1]");
+  }
+  if (decay <= 0 || decay > 1) {
+    throw new Error("decay must be in (0, 1]");
+  }
+  if (epsilon < 0) {
+    throw new Error("epsilon must be >= 0");
+  }
+
+  const visited = new Set<Hash>();
+
+  // Create Liquid engine
+  const engine = createLiquidEngine(store, varStore, decay);
+
+  return await renderNode(
+    engine,
+    store,
+    varStore,
+    hash,
+    resolution,
+    decay,
+    epsilon,
+    visited,
+  );
+}
+
+/**
+ * Create a Liquid engine instance with custom render tag
+ */
+function createLiquidEngine(
+  store: Store,
+  varStore: VariableStore,
+  globalDecay: number,
+): Liquid {
+  const engine = new Liquid({
+    strictFilters: false,
+    strictVariables: false,
+  });
+
+  // Type for storing parsed tag data
+  type RenderTagState = {
+    variable: string;
+    decay: number | undefined;
+  };
+
+  // Register custom {% render %} tag
+  // Capture store, varStore, globalDecay in closure
+  engine.registerTag("render", {
+    parse(token: TagToken) {
+      // Parse "variable" or "variable, decay: 0.7" syntax
+      const args = token.args.trim();
+      const match = args.match(/^(\S+)(?:,\s*decay:\s*([\d.]+))?$/);
+
+      if (!match) {
+        throw new Error(
+          `Invalid render tag syntax: ${args}. Expected: {% render variable %} or {% render variable, decay: 0.7 %}`,
+        );
+      }
+
+      // Store parsed values on the tag instance
+      const state = this as unknown as RenderTagState;
+      state.variable = match[1] as string;
+      state.decay = match[2] ? Number.parseFloat(match[2]) : undefined;
+
+      // Validate decay if provided
+      if (state.decay !== undefined) {
+        if (state.decay <= 0 || state.decay > 1) {
+          throw new Error("decay must be in (0, 1]");
+        }
+      }
+    },
+
+    async render(ctxLiquid: Context) {
+      // Access parsed values
+      const state = this as unknown as RenderTagState;
+      const variable = state.variable;
+      const explicitDecay = state.decay;
+
+      // Resolve the variable to a hash (split on dots for nested paths)
+      const variablePath = variable.split(".");
+      const value = ctxLiquid.get(variablePath);
+
+      // Handle null/undefined - render as empty
+      if (value === null || value === undefined) {
+        return "";
+      }
+
+      // Handle non-string values - render as empty
+      if (typeof value !== "string") {
+        return "";
+      }
+
+      const nodeHash = value as Hash;
+
+      // Get current render context
+      const currentResolution = ctxLiquid.get(["resolution"]) as number;
+      const currentEpsilon = ctxLiquid.get(["epsilon"]) as number;
+
+      // Compute child resolution using decay priority:
+      // 1. Template explicit decay (explicitDecay)
+      // 2. Global decay (from CLI/options)
+      // 3. Engine default (0.5)
+      const effectiveDecay =
+        explicitDecay !== undefined
+          ? explicitDecay
+          : (globalDecay ?? DEFAULT_DECAY);
+      const childResolution = currentResolution * effectiveDecay;
+
+      // Recursively render the referenced node
+      const visited = ctxLiquid.get(["__visited"]) as Set<Hash>;
+      const output = await renderNode(
+        engine,
+        store,
+        varStore,
+        nodeHash,
+        childResolution,
+        globalDecay,
+        currentEpsilon,
+        visited,
+      );
+
+      return output;
+    },
+  });
+
+  return engine;
+}
+
+/**
+ * Render a single node with template or fallback to cas: reference
+ */
+async function renderNode(
+  engine: Liquid,
+  store: Store,
+  varStore: VariableStore,
+  hash: Hash,
+  currentResolution: number,
+  _globalDecay: number,
+  epsilon: number,
+  visited: Set<Hash>,
+): Promise<string> {
+  // Check if resolution is below threshold
+  if (currentResolution < epsilon + FLOAT_TOLERANCE) {
+    return `cas:${hash}`;
+  }
+
+  // Fetch the node
+  const node = store.get(hash);
+  if (node === null) {
+    return `cas:${hash}`;
+  }
+
+  // Cycle detection
+  if (visited.has(hash)) {
+    return `cas:${hash}`;
+  }
+  visited.add(hash);
+
+  try {
+    // Try to find a template for this node's type
+    const template = await findTemplate(store, varStore, node.type);
+
+    if (template === null) {
+      // No template found - this is handled by the caller (fallback to YAML)
+      // For now, return a simple representation
+      visited.delete(hash);
+      return renderFallback(store, node.payload);
+    }
+
+    // Render using the template
+    const context = {
+      resolution: currentResolution,
+      epsilon,
+      hash,
+      payload: node.payload,
+      type: node.type,
+      timestamp: node.timestamp,
+      __visited: visited, // Pass visited set through context
+    };
+
+    const output = await engine.parseAndRender(template, context);
+
+    visited.delete(hash);
+    return output;
+  } catch (error) {
+    visited.delete(hash);
+    throw error;
+  }
+}
+
+/**
+ * Find a template for a given type hash
+ */
+async function findTemplate(
+  store: Store,
+  varStore: VariableStore,
+  typeHash: Hash,
+): Promise<string | null> {
+  const varName = `@ucas/template/text/${typeHash}`;
+
+  try {
+    // Find the string schema hash (we need this to query variables)
+    const stringSchema = await putSchema(store, { type: "string" });
+
+    const variable = varStore.get(varName, stringSchema);
+    if (variable === null) {
+      return null;
+    }
+
+    const templateNode = store.get(variable.value);
+    if (templateNode === null) {
+      return null;
+    }
+
+    // Template should be a string
+    if (typeof templateNode.payload !== "string") {
+      return null;
+    }
+
+    return templateNode.payload;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Fallback renderer for nodes without templates
+ */
+function renderFallback(_store: Store, payload: unknown): string {
+  // Simple YAML-like representation
+  if (payload === null) {
+    return "null\n";
+  }
+
+  if (typeof payload === "string") {
+    return `${payload}\n`;
+  }
+
+  if (typeof payload === "number" || typeof payload === "boolean") {
+    return `${payload}\n`;
+  }
+
+  if (Array.isArray(payload)) {
+    if (payload.length === 0) {
+      return "[]\n";
+    }
+    return `- ${payload.join("\n- ")}\n`;
+  }
+
+  if (typeof payload === "object") {
+    const obj = payload as Record<string, unknown>;
+    const keys = Object.keys(obj);
+    if (keys.length === 0) {
+      return "{}\n";
+    }
+    const pairs = keys.map((key) => `${key}: ${obj[key]}`);
+    return `${pairs.join("\n")}\n`;
+  }
+
+  return "null\n";
+}

packages/json-cas/src/render.ts

@@ -1,10 +1,13 @@
-import { refs } from "./schema.js";
+import { renderWithTemplate } from "./liquid-render.js";
+import { putSchema, refs } from "./schema.js";
 import type { Hash, Store } from "./types.js";
+import type { VariableStore } from "./variable-store.js";
 
 export type RenderOptions = {
   resolution?: number; // (0, 1], default 1.0
   decay?: number; // (0, 1], default 0.5
   epsilon?: number; // >= 0, default 0.01
+  varStore?: VariableStore; // Optional: for template lookup
 };
 
 const DEFAULT_RESOLUTION = 1.0;
@@ -16,6 +19,8 @@ const FLOAT_TOLERANCE = 1e-10;
 /**
  * Render a CAS node as YAML with resolution-based decay.
  * When resolution ≤ epsilon, nodes are rendered as opaque `cas:<hash>` references.
+ * This is the synchronous version without template support.
+ * For template support, use renderAsync() with varStore.
  */
 export function render(
   store: Store,
@@ -38,10 +43,78 @@ export function render(
   }
 
   const visited = new Set<Hash>();
-
   return renderNode(store, hash, resolution, decay, epsilon, visited);
 }
 
+/**
+ * Async render with LiquidJS template support.
+ * When resolution ≤ epsilon, nodes are rendered as opaque `cas:<hash>` references.
+ * If varStore is provided, attempts to use LiquidJS templates first, fallback to YAML.
+ */
+export async function renderAsync(
+  store: Store,
+  hash: Hash,
+  options?: RenderOptions,
+): Promise<string> {
+  const resolution = options?.resolution ?? DEFAULT_RESOLUTION;
+  const decay = options?.decay ?? DEFAULT_DECAY;
+  const epsilon = options?.epsilon ?? DEFAULT_EPSILON;
+  const varStore = options?.varStore;
+
+  // Validate parameters
+  if (resolution < 0 || resolution > 1) {
+    throw new Error("resolution must be in [0, 1]");
+  }
+  if (decay <= 0 || decay > 1) {
+    throw new Error("decay must be in (0, 1]");
+  }
+  if (epsilon < 0) {
+    throw new Error("epsilon must be >= 0");
+  }
+
+  // If varStore provided, try template rendering first
+  if (varStore !== undefined) {
+    try {
+      const node = store.get(hash);
+      if (node !== null) {
+        // Check if a template exists for this type
+        const templateExists = await hasTemplate(store, varStore, node.type);
+        if (templateExists) {
+          return await renderWithTemplate(store, varStore, hash, {
+            resolution,
+            decay,
+            epsilon,
+          });
+        }
+      }
+    } catch {
+      // Fall through to YAML rendering
+    }
+  }
+
+  // Fallback to YAML rendering
+  const visited = new Set<Hash>();
+  return renderNode(store, hash, resolution, decay, epsilon, visited);
+}
+
+/**
+ * Check if a template exists for a given type
+ */
+async function hasTemplate(
+  store: Store,
+  varStore: VariableStore,
+  typeHash: Hash,
+): Promise<boolean> {
+  const varName = `@ucas/template/text/${typeHash}`;
+  try {
+    const stringSchema = await putSchema(store, { type: "string" });
+    const variable = varStore.get(varName, stringSchema);
+    return variable !== null;
+  } catch {
+    return false;
+  }
+}
+
 function renderNode(
   store: Store,
   hash: Hash,