fix(knowledge): give a broad reader's wider walk half of what the leg has left

The rerank and hydration of whatever is found — the first walk's candidates at least — keep the rest, so a wider walk that runs out of its share can no longer take the leg's results with it.

Author: waleedlatif1

apps/sim/lib/knowledge/search/queries.test.ts

@@ -1372,6 +1372,15 @@ describe('permitted-document planner', () => {
       },
     })
     expect(rows.map((row) => row.id)).toEqual(['short-hit'])
+    /** The wider walk ran under a share of the leg's budget, not all of it. */
+    const timeouts = statements()
+      .filter((query) => query.sql.includes("'statement_timeout'"))
+      .map((query) =>
+        Number(query.params.find((param) => typeof param === 'string' && /^\d+$/.test(param)))
+      )
+      .filter((value) => Number.isFinite(value))
+    expect(Math.min(...timeouts)).toBeLessThanOrEqual(5000)
+    expect(Math.max(...timeouts)).toBeGreaterThan(5000)
   })
 
   it('walks an indexed source a bounded caller is a member of instead of ranking it exactly', async () => {

apps/sim/lib/knowledge/search/queries.ts

@@ -1666,6 +1666,11 @@ async function selectVectorResults(params: SearchParams): Promise<SearchResult[]
              * budget the first walk's candidates stand.
              */
             const walked = selected
+            /**
+             * The wider walk gets half of what the leg has left, so the rerank and hydration of
+             * whatever is found — the first walk's candidates at least — still have the rest.
+             */
+            const wideBudget = params.budget?.capped(Math.floor(params.budget.remaining() / 2))
             try {
               const wider = await withVectorScanSettings(
                 (executor) =>
@@ -1680,14 +1685,16 @@ async function selectVectorResults(params: SearchParams): Promise<SearchResult[]
             )}
             ORDER BY ${candidateDistance} LIMIT ${candidateLimit}
           `),
-                params.budget,
+                wideBudget,
                 'vector.candidate_search',
                 WIDE_WALK_SCAN_TUPLES
               )
               const seen = new Set(walked.map(({ id }) => id))
               selected = [...walked, ...wider.filter(({ id }) => !seen.has(id))]
             } catch (error) {
-              if (!params.budget?.isTimeout(error)) throw error
+              if (!wideBudget?.isTimeout(error)) throw error
+              /** Only the wider walk's share was spent; the leg's own deadline still governs. */
+              params.budget?.remaining()
               selected = walked
             }
           }