Fix ?. + chained || literal fallback parsing to preserve left-to-right short-circuit semantics (#94)

* Initial plan

* fix parser short-circuit for chained literal OR fallbacks

Co-authored-by: aarne <82001+aarne@users.noreply.github.com>

* test and parser update for chained literal OR fallback order

Co-authored-by: aarne <82001+aarne@users.noreply.github.com>

* test mixed || ?? chain semantics and add release changeset

Co-authored-by: aarne <82001+aarne@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: aarne <82001+aarne@users.noreply.github.com>

Author: Copilot

.changeset/tough-cups-smoke.md

@@ -0,0 +1,6 @@
+---
+"@stackables/bridge": patch
+"@stackables/bridge-parser": patch
+---
+
+Fix chained `||` literal fallback parsing so authored left-to-right short-circuiting is preserved after safe pulls (`?.`), and add regression coverage for mixed `||` + `??` chains.

packages/bridge-parser/src/parser/parser.ts

@@ -5237,13 +5237,18 @@ function buildBridgeBody(
 
     let falsyFallback: string | undefined;
     let falsyControl: ControlFlowInstruction | undefined;
+    let hasTruthyLiteralFallback = false;
     for (const alt of subs(wireNode, "nullAlt")) {
+      if (hasTruthyLiteralFallback) break;
       const altResult = extractCoalesceAlt(alt, lineNum);
       if ("literal" in altResult) {
         falsyFallback = altResult.literal;
+        hasTruthyLiteralFallback = Boolean(JSON.parse(altResult.literal));
       } else if ("control" in altResult) {
+        falsyFallback = undefined;
         falsyControl = altResult.control;
       } else {
+        falsyFallback = undefined;
         sourceParts.push({ ref: altResult.sourceRef, isPipeFork: false });
       }
     }

packages/bridge/test/coalesce-cost.test.ts

@@ -649,6 +649,50 @@ bridge Query.lookup {
     assert.equal(data.label, "fallback");
   });
 
+  test("?. with chained || literals short-circuits at first truthy literal", async () => {
+    const doc = parseBridge(`version 1.5
+const lorem = {
+  "ipsum":"dolor sit amet",
+  "consetetur":8.9
+}
+
+bridge Query.lookup {
+  with const
+  with output as o
+
+  o.label <- const.lorem.ipsums?.kala || "A" || "B"
+}`);
+    const gateway = createGateway(typeDefs, doc, { tools: {} });
+    const executor = buildHTTPExecutor({ fetch: gateway.fetch as any });
+
+    const result: any = await executor({
+      document: parse(`{ lookup(q: "x") { label } }`),
+    });
+    assert.equal(result.data.lookup.label, "A");
+  });
+
+  test("mixed || and ?? remains left-to-right with first truthy || winner", async () => {
+    const doc = parseBridge(`version 1.5
+const lorem = {
+  "ipsum": "dolor sit amet",
+  "consetetur": 8.9
+}
+
+bridge Query.lookup {
+  with const
+  with output as o
+
+  o.label <- const.lorem.kala || const.lorem.ipsums?.mees || "B" ?? "C"
+}`);
+    const gateway = createGateway(typeDefs, doc, { tools: {} });
+    const executor = buildHTTPExecutor({ fetch: gateway.fetch as any });
+
+    const result: any = await executor({
+      document: parse(`{ lookup(q: "x") { label } }`),
+    });
+    assert.equal(result.data.lookup.label, "B");
+  });
+
   test("?. passes through value when tool succeeds", async () => {
     const { data } = await run(
       `version 1.5