fix(tests): add sinks to keep charms reactive in pull mode

In pull mode, charms need an effect (sink) pulling from them to stay
reactive when inputs change. Tests that set values externally and expect
UI updates need to create a sink on the result cell.

This is the correct approach rather than adding a blanket sink to all
recipes - the test explicitly declares its intent to observe reactivity.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: seefeldb

packages/generated-patterns/integration/pattern-harness.ts

@@ -88,6 +88,8 @@ export async function runPatternScenario(scenario: PatternIntegrationScenario) {
   const result = runtime.run(tx, patternFactory, argument, resultCell);
   tx.commit();
 
+  // Sink to keep the result reactive
+  result.sink(() => {});
   await runtime.idle();
 
   let stepIndex = 0;

packages/patterns/integration/counter.test.ts

@@ -16,6 +16,7 @@ describe("counter direct operations test", () => {
   let identity: Identity;
   let cc: CharmsController;
   let charm: CharmController;
+  let charmSinkCancel: (() => void) | undefined;
 
   beforeAll(async () => {
     identity = await Identity.generate({ implementation: "noble" });
@@ -33,9 +34,15 @@ describe("counter direct operations test", () => {
       program, // We operate on the charm in this thread
       { start: true },
     );
+
+    // In pull mode, create a sink to keep the charm reactive when inputs change.
+    // Without this, setting values won't trigger recipe re-computation.
+    const resultCell = cc.manager().getResult(charm.getCell());
+    charmSinkCancel = resultCell.sink(() => {});
   });
 
   afterAll(async () => {
+    charmSinkCancel?.();
     if (cc) await cc.dispose();
   });
 

packages/patterns/integration/ct-render.test.ts

@@ -15,6 +15,7 @@ describe("ct-render integration test", () => {
   let identity: Identity;
   let cc: CharmsController;
   let charm: CharmController;
+  let charmSinkCancel: (() => void) | undefined;
 
   beforeAll(async () => {
     identity = await Identity.generate({ implementation: "noble" });
@@ -34,9 +35,14 @@ describe("ct-render integration test", () => {
       // We operate on the charm in this thread
       { start: true },
     );
+
+    // In pull mode, create a sink to keep the charm reactive when inputs change.
+    const resultCell = cc.manager().getResult(charm.getCell());
+    charmSinkCancel = resultCell.sink(() => {});
   });
 
   afterAll(async () => {
+    charmSinkCancel?.();
     if (cc) await cc.dispose();
   });
 

packages/patterns/integration/nested-counter.test.ts

@@ -16,6 +16,7 @@ describe("nested counter integration test", () => {
   let identity: Identity;
   let cc: CharmsController;
   let charm: CharmController;
+  let charmSinkCancel: (() => void) | undefined;
 
   beforeAll(async () => {
     identity = await Identity.generate({ implementation: "noble" });
@@ -34,9 +35,14 @@ describe("nested counter integration test", () => {
       program, // We operate on the charm in this thread
       { start: true },
     );
+
+    // In pull mode, create a sink to keep the charm reactive when inputs change.
+    const resultCell = cc.manager().getResult(charm.getCell());
+    charmSinkCancel = resultCell.sink(() => {});
   });
 
   afterAll(async () => {
+    charmSinkCancel?.();
     if (cc) await cc.dispose();
   });