fix: match the server's NATS subject encoding for segments with dots

.github/workflows/test.yml

@@ -15,5 +15,6 @@ jobs:
           node-version: 24
       - run: npm install
       - run: node --check client.js
+      - run: npm test
       # construct the client so the vendored proto is parsed at load time
       - run: node -e "new (require('./client.js').PromptClient)({host:'localhost:1'})"

client.js

@@ -17,8 +17,17 @@ function loadService() {
   return grpc.loadPackageDefinition(def).priompt.v1;
 }
 
+// subject maps a prompt URI to its NATS subject exactly as the server's
+// pubsub.Subject does: each URI segment is one subject token, with every byte
+// outside [A-Za-z0-9_-] percent-encoded in uppercase hex ("." is the NATS token
+// separator), so priompt://acme.corp/x/a.b -> priompt.acme%2Ecorp.x.a%2Eb.
 function subject(uri) {
-  return "priompt." + uri.replace("priompt://", "").replace(/\//g, ".");
+  const path = uri.startsWith("priompt://") ? uri.slice("priompt://".length) : uri;
+  const token = (seg) =>
+    Array.from(Buffer.from(seg, "utf8"), (c) =>
+      /[A-Za-z0-9_-]/.test(String.fromCharCode(c)) ? String.fromCharCode(c) : "%" + c.toString(16).toUpperCase().padStart(2, "0")
+    ).join("");
+  return "priompt." + path.split("/").map(token).join(".");
 }
 
 // parseUrl splits a priompt://<token>@host:port connection URL into { host,
@@ -152,4 +161,4 @@ class PromptClient {
   }
 }
 
-module.exports = { PromptClient };
+module.exports = { PromptClient, subject };

package.json

@@ -29,7 +29,8 @@
     "access": "public"
   },
   "scripts": {
-    "sync-proto": "node -e \"const fs=require('fs');fs.mkdirSync('proto/priompt/v1',{recursive:true});fs.copyFileSync('../proto/proto/priompt/v1/prompt.proto','proto/priompt/v1/prompt.proto')\""
+    "sync-proto": "node -e \"const fs=require('fs');fs.mkdirSync('proto/priompt/v1',{recursive:true});fs.copyFileSync('../proto/proto/priompt/v1/prompt.proto','proto/priompt/v1/prompt.proto')\"",
+    "test": "node --test \"test/*.test.js\""
   },
   "dependencies": {
     "@grpc/grpc-js": "^1.10.0",

test/subject.test.js

@@ -0,0 +1,26 @@
+const test = require("node:test");
+const assert = require("node:assert");
+const { subject } = require("../client");
+
+// Cases mirror the server's internal/pubsub TestSubjectIsInjective and
+// TestSubjectMapping (priompt/priompt#33).
+test("distinct URIs map to distinct subjects", () => {
+  for (const [a, b] of [
+    ["priompt://acme/a.b", "priompt://acme/a/b"],
+    ["priompt://acme/corp/x", "priompt://acme.corp/x"],
+    ["priompt://acme/a.b/c", "priompt://acme/a/b.c"],
+  ]) {
+    assert.notStrictEqual(subject(a), subject(b), `${a} and ${b} share a subject`);
+  }
+});
+
+test("dot-free URIs keep their subject", () => {
+  assert.strictEqual(subject("priompt://acme/support/agent"), "priompt.acme.support.agent");
+  assert.strictEqual(subject("priompt://acme/support/agent-v2_x"), "priompt.acme.support.agent-v2_x");
+});
+
+test("bytes outside [A-Za-z0-9_-] are percent-encoded with uppercase hex", () => {
+  assert.strictEqual(subject("priompt://acme.corp/x/a.b"), "priompt.acme%2Ecorp.x.a%2Eb");
+  // Encoded per UTF-8 byte, as the server's Go loop does.
+  assert.strictEqual(subject("priompt://acme/café"), "priompt.acme.caf%C3%A9");
+});