From 771242ea3d3cb67400366a89546d8ef3db7360dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=A4cker=2C=20Henning?= <henning.haecker@vector.com>
Date: Fri, 24 Apr 2026 16:16:22 +0200
Subject: [PATCH] fix(start-work): prefer nested session plan refs

---
 src/hooks/start-work/index.test.ts            | 49 +++++++++++++++++++
 src/hooks/start-work/session-plan-affinity.ts | 26 ++++++++--
 2 files changed, 70 insertions(+), 5 deletions(-)

diff --git a/src/hooks/start-work/index.test.ts b/src/hooks/start-work/index.test.ts
index ff715e868..70b25596e 100644
--- a/src/hooks/start-work/index.test.ts
+++ b/src/hooks/start-work/index.test.ts
@@ -281,6 +281,55 @@ You are starting a Sisyphus work session.
       expect(state?.active_plan).toBe(newPlanPath)
     })
 
+    test("should still find nested plan references when direct input fields contain a different plan path", async () => {
+      // given - direct path points to plan-a but nested serialized input also references newer plan-b
+      const plansDir = join(testDir, ".sisyphus", "plans")
+      mkdirSync(plansDir, { recursive: true })
+
+      const planAPath = join(plansDir, "plan-a.md")
+      const planBPath = join(plansDir, "plan-b.md")
+      writeFileSync(planAPath, "# Plan A\n- [ ] Task A")
+      writeFileSync(planBPath, "# Plan B\n- [ ] Task B")
+
+      const hook = createStartWorkHook({
+        directory: testDir,
+        client: {
+          session: {
+            messages: async () => ({
+              data: [
+                {
+                  parts: [
+                    {
+                      input: {
+                        path: `Legacy reference ${planAPath}`,
+                        metadata: {
+                          selectedPlan: `Current reference ${planBPath}`,
+                        },
+                      },
+                    },
+                  ],
+                },
+              ],
+            }),
+          },
+        },
+      } as Parameters<typeof createStartWorkHook>[0])
+      const output = {
+        parts: [{ type: "text", text: createStartWorkPrompt() }],
+      }
+
+      // when
+      await hook["chat.message"](
+        { sessionID: "session-123" },
+        output,
+      )
+
+      // then - latest nested reference should still be discoverable and selected
+      const state = readBoulderState(testDir)
+      expect(state?.active_plan).toBe(planBPath)
+      expect(output.parts[0].text).toContain("plan-b")
+    })
+
     test("should replace $SESSION_ID placeholder", async () => {
       // given - hook and message with placeholder
       const hook = createStartWorkHook(createMockPluginInput())
diff --git a/src/hooks/start-work/session-plan-affinity.ts b/src/hooks/start-work/session-plan-affinity.ts
index 9ba14c291..5de2e1162 100644
--- a/src/hooks/start-work/session-plan-affinity.ts
+++ b/src/hooks/start-work/session-plan-affinity.ts
@@ -29,20 +29,36 @@ function extractPlanPathsFromText(directory: string, text: string): string[] {
   return matches.map((match) => normalizePlanPath(directory, match))
 }
 
+function extractPlanPathsFromValue(directory: string, value: unknown): string[] {
+  if (typeof value === "string") {
+    return extractPlanPathsFromText(directory, value)
+  }
+
+  if (Array.isArray(value)) {
+    return value.flatMap((item) => extractPlanPathsFromValue(directory, item))
+  }
+
+  if (value && typeof value === "object") {
+    return Object.values(value).flatMap((item) => extractPlanPathsFromValue(directory, item))
+  }
+
+  return []
+}
+
 function extractPlanPathsFromInput(directory: string, input: Record<string, unknown> | undefined): string[] {
   if (!input) {
     return []
   }
 
+  const nestedCandidates = Object.entries(input)
+    .filter(([key]) => key !== "filePath" && key !== "path" && key !== "file")
+    .flatMap(([, value]) => extractPlanPathsFromValue(directory, value))
+
   const directCandidates = [input.filePath, input.path, input.file]
     .filter((value): value is string => typeof value === "string")
     .flatMap((value) => extractPlanPathsFromText(directory, value))
 
-  if (directCandidates.length > 0) {
-    return directCandidates
-  }
-
-  return extractPlanPathsFromText(directory, JSON.stringify(input))
+  return [...new Set([...nestedCandidates, ...directCandidates])]
 }
 
 export async function findRecentSessionPlanPath(input: {