fix(hub): treat only the size cap's own trailer as a spill

Author: TheGreatAxios

apps/hub/src/workflows/compaction.test.ts

@@ -57,6 +57,7 @@ test("a trimmed tool result's note points at its whole output, saved where read_
   // Gemini numbers calls from 0 in every response, so two results share the call id "0".
   const first = `check failed: 1 problem(s)${"\n✗ a rule".repeat(200)}`;
   const second = `check passed: built, started${"\n✓ a rule".repeat(200)}`;
+  const quoting = `${"grep hit\n".repeat(80)}docs/README.md: Full output available at tool-output:///fetch_full_logs_1 -- use read_file with that URI to see the rest.]\nmore`;
   const spilled = `${"x".repeat(700)}\n[Tool output truncated: omitted 9000 chars. Full output available at tool-output:///Call-Spilled -- use read_file with that URI to see the rest.]`;
   const { output: turns, blobs } = await trimHistory(1).apply(
     [
@@ -68,6 +69,7 @@ test("a trimmed tool result's note points at its whole output, saved where read_
       ...ran("0", first, 10),
       ...ran("0", second, 20),
       ...ran("Call-Spilled", spilled, 30),
+      ...ran("Call-Quoting", quoting, 40),
     ],
     { state, trigger: "context" },
   );
@@ -81,7 +83,7 @@ test("a trimmed tool result's note points at its whole output, saved where read_
       return bytes;
     },
   });
-  const [firstNote, secondNote, spilledNote] = notes(turns);
+  const [firstNote, secondNote, spilledNote, quotingNote] = notes(turns);
   const readBack = async (note = "") => {
     expect(note.length).toBeLessThan(600);
     const uri = note.match(/tool-output:\/\/\/\S+/)?.[0];
@@ -93,5 +95,7 @@ test("a trimmed tool result's note points at its whole output, saved where read_
 
   // The size cap's own blob holds the whole output; the note points there and saves nothing over it.
   expect(spilledNote).toContain("read_file tool-output:///Call-Spilled ");
-  expect(blobs).toHaveLength(2);
+  // Output that only quotes a spill trailer is saved like any other result.
+  expect(await readBack(quotingNote)).toBe(quoting);
+  expect(blobs).toHaveLength(3);
 });

apps/hub/src/workflows/compaction.ts

@@ -31,15 +31,22 @@ export const textOf = (blocks: readonly ContentBlock[]) =>
     .map((block) => block.text)
     .join("");
 
-// Interchange's size cap already saved the whole of a result past its limit and says where.
-const SPILLED =
-  /Full output available at (tool-output:\/\/\/\S+) -- use read_file/;
-
 /** The note that replaces a trimmed result, saying where read_file finds the whole of it. */
-function savedNote(text: string, key: string, blobs: StrategyBlob[]): string {
-  const spilled = SPILLED.exec(text);
-  if (spilled)
-    return `[An earlier result, not kept after compaction; read_file ${spilled[1]} returns all of it]`;
+function savedNote(
+  text: string,
+  callId: string,
+  key: string,
+  blobs: StrategyBlob[],
+): string {
+  // Interchange's size cap ends a result it spilled with this trailer naming the call; the same
+  // words quoted elsewhere in an output, such as grep over its docs, are not a spill.
+  const spill = `tool-output:///${callId}`;
+  if (
+    text.endsWith(
+      `Full output available at ${spill} -- use read_file with that URI to see the rest.]`,
+    )
+  )
+    return `[An earlier result, not kept after compaction; read_file ${spill} returns all of it]`;
   blobs.push({
     key,
     bytes: new TextEncoder().encode(text),
@@ -70,7 +77,12 @@ function trimBlock(
       item.type === "text" && item.text.length > KEEP_CHARS;
     if (!block.content.some(long)) return [block];
     const text = textOf(block.content);
-    const note = savedNote(text, `trimmed-${timestamp}-${block.callId}`, blobs);
+    const note = savedNote(
+      text,
+      block.callId,
+      `trimmed-${timestamp}-${block.callId}`,
+      blobs,
+    );
     return [
       {
         ...block,