test(btmsg): add regression tests for named column access and camelCase serialization

Covers the CRITICAL status vs system_prompt bug (positional index 7),
JOIN alias disambiguation, serde camelCase serialization, TypeScript
bridge IPC commands, and plantuml hex encoding algorithm.
49 new tests: 8 btmsg.rs + 7 bttask.rs + 8 sidecar + 17 btmsg-bridge.ts + 10 bttask-bridge.ts + 7 plantuml-encode.ts

v2/src/lib/utils/plantuml-encode.test.ts

@@ -0,0 +1,67 @@
+import { describe, it, expect } from 'vitest';
+
+// ---- REGRESSION: PlantUML hex encoding ----
+// Bug: ArchitectureTab had a broken encoding chain (rawDeflate returned input unchanged,
+// encode64 was hex encoding masquerading as base64). Fixed by collapsing to single
+// plantumlEncode function using ~h hex prefix (plantuml.com text encoding standard).
+//
+// This test validates the encoding algorithm matches what ArchitectureTab.svelte uses.
+
+/** Reimplementation of the plantumlEncode function from ArchitectureTab.svelte */
+function plantumlEncode(text: string): string {
+  const bytes = unescape(encodeURIComponent(text));
+  let hex = '~h';
+  for (let i = 0; i < bytes.length; i++) {
+    hex += bytes.charCodeAt(i).toString(16).padStart(2, '0');
+  }
+  return hex;
+}
+
+describe('plantumlEncode', () => {
+  it('produces ~h prefix for hex encoding', () => {
+    const result = plantumlEncode('@startuml\n@enduml');
+    expect(result.startsWith('~h')).toBe(true);
+  });
+
+  it('encodes ASCII correctly', () => {
+    const result = plantumlEncode('AB');
+    // A=0x41, B=0x42
+    expect(result).toBe('~h4142');
+  });
+
+  it('encodes simple PlantUML source', () => {
+    const result = plantumlEncode('@startuml\n@enduml');
+    // Each character maps to its hex code
+    const expected = '~h' + Array.from('@startuml\n@enduml')
+      .map(c => c.charCodeAt(0).toString(16).padStart(2, '0'))
+      .join('');
+    expect(result).toBe(expected);
+  });
+
+  it('handles Unicode characters', () => {
+    // UTF-8 multi-byte: é = 0xc3 0xa9
+    const result = plantumlEncode('café');
+    expect(result.startsWith('~h')).toBe(true);
+    // c=63, a=61, f=66, é=c3a9
+    expect(result).toBe('~h636166c3a9');
+  });
+
+  it('handles empty string', () => {
+    expect(plantumlEncode('')).toBe('~h');
+  });
+
+  it('produces valid URL-safe output (no special chars beyond hex digits)', () => {
+    const result = plantumlEncode('@startuml\ntitle Test\nA -> B\n@enduml');
+    // After ~h prefix, only hex digits [0-9a-f]
+    const hexPart = result.slice(2);
+    expect(hexPart).toMatch(/^[0-9a-f]+$/);
+  });
+
+  it('generates correct URL for plantuml.com', () => {
+    const source = '@startuml\nA -> B\n@enduml';
+    const encoded = plantumlEncode(source);
+    const url = `https://www.plantuml.com/plantuml/svg/${encoded}`;
+    expect(url).toContain('plantuml.com/plantuml/svg/~h');
+    expect(url.length).toBeGreaterThan(50);
+  });
+});