diff --git a/services/minecraft/src/cognitive/conscious/js-planner.test.ts b/services/minecraft/src/cognitive/conscious/js-planner.test.ts
index 296ab0de4..ebb2cb623 100644
--- a/services/minecraft/src/cognitive/conscious/js-planner.test.ts
+++ b/services/minecraft/src/cognitive/conscious/js-planner.test.ts
@@ -126,6 +126,19 @@ describe('javaScriptPlanner', () => {
     expect(planned.actions.map(a => a.action)).toEqual([{ tool: 'chat', params: { message: '2 oak_log' } }])
   })
 
+  it('does not expose stringified return mirror on prevRun', async () => {
+    const planner = new JavaScriptPlanner()
+    const executeAction = vi.fn(async action => `ok:${action.tool}`)
+
+    await planner.evaluate(`
+      const inv = [{ name: "oak_log", count: 2 }]
+      return inv
+    `, actions, globals, executeAction)
+
+    const planned = await planner.evaluate('return Object.prototype.hasOwnProperty.call(prevRun, "returnValue")', actions, globals, executeAction)
+    expect(planned.returnValue).toBe('false')
+  })
+
   it('provides snapshot globals in script scope', async () => {
     const planner = new JavaScriptPlanner()
     const executeAction = vi.fn(async action => `ok:${action.tool}`)
diff --git a/services/minecraft/src/cognitive/conscious/js-planner.ts b/services/minecraft/src/cognitive/conscious/js-planner.ts
index bd67a7b03..31640617e 100644
--- a/services/minecraft/src/cognitive/conscious/js-planner.ts
+++ b/services/minecraft/src/cognitive/conscious/js-planner.ts
@@ -160,7 +160,6 @@ export class JavaScriptPlanner {
           })
 
       if (isRecord(this.sandbox.lastRun)) {
-        this.sandbox.lastRun.returnValue = returnValue
         this.sandbox.lastRun.returnRaw = result
       }
 
diff --git a/services/minecraft/src/cognitive/conscious/prompts/brain-prompt.md b/services/minecraft/src/cognitive/conscious/prompts/brain-prompt.md
index 2dc812974..25f6238b7 100644
--- a/services/minecraft/src/cognitive/conscious/prompts/brain-prompt.md
+++ b/services/minecraft/src/cognitive/conscious/prompts/brain-prompt.md
@@ -21,7 +21,7 @@ You are an autonomous agent playing Minecraft.
    - Globals refreshed every turn: `snapshot`, `self`, `environment`, `social`, `threat`, `attention`, `autonomy`, `event`, `now`, `query`, `bot`, `mineflayer`, `currentInput`, `llmLog`, `actionQueue`, `noActionBudget`, `errorBurstGuard`.
    - Persistent globals: `mem` (cross-turn memory), `lastRun` (this run), `prevRun` (previous run), `lastAction` (latest action result), `log(...)`.
    - Budget helpers: `setNoActionBudget(n)` and `getNoActionBudget()` control/inspect eval-only no-action follow-up budget.
-   - Cross-turn result access: use `prevRun.returnRaw` for typed values (arrays/objects); `prevRun.returnValue` is stringified for display/logging.
+   - Cross-turn result access: use `prevRun.returnRaw` for typed values (arrays/objects). If you need text output, stringify `returnRaw` explicitly.
    - `forget_conversation()` clears conversation memory (`conversationHistory` and `lastLlmInputSnapshot`) for prompt/debug reset workflows.
    - Last script outcome is also echoed in the next turn as `[SCRIPT]` context (return value, action stats, and logs).
    - Maximum tool calls per turn: 5.
@@ -116,7 +116,7 @@ Silent-eval pattern (strongly encouraged):
 - Use no-action evaluation turns to inspect uncertain values before committing to world actions.
 - Good pattern:
   - Turn A: `let blocksToMine = someFunc(); blocksToMine`
-  - Turn B: inspect `[SCRIPT]` return / `llmLog`, then act: `await collectBlocks({ type: ..., num: ... })`
+  - Turn B: inspect `prevRun.returnRaw` / `llmLog`, then act: `await collectBlocks({ type: ..., num: ... })`
 - Prefer this when a wrong action would be costly, dangerous, or hard to undo.
 - A `no_actions` follow-up after an eval-only turn is normal; follow-ups are budgeted and can chain for multi-step reasoning.
 - Default no-action follow-up budget is 3 and max is 8.
@@ -127,8 +127,10 @@ Value-first rule (mandatory for read -> action flows):
 - If a request depends on observed world/query data, first run an evaluation-only turn and end with the concrete value expression.
 - Do not call world/chat tools in that first turn.
 - End eval turns with a concrete final expression (for example `inv`, `target`, `summary`) so `[SCRIPT]` captures it.
-- In the next turn, use `[SCRIPT] Last eval return=...` as the source of truth for tool parameters/messages.
+- In the next turn, use `prevRun.returnRaw` as the source of truth for tool parameters/messages.
 - Do not re-query the same read value in the follow-up turn; use the persisted value to avoid TOCTOU drift.
+- For typed follow-up logic, use `prevRun.returnRaw` (or `lastRun.returnRaw` for current-turn chaining).
+- If you need a string for chat/logging, stringify raw data yourself (for example `JSON.stringify(prevRun.returnRaw)`).
 - Avoid acting on unresolved intermediate variables when a concrete returned value can be verified first.
 - For explicit user tasks (e.g. "get X", "craft Y", "go to Z"), do not stay in repeated evaluation-only turns.
 - After a small number of evaluation turns, the next turn must either:
@@ -137,7 +139,8 @@ Value-first rule (mandatory for read -> action flows):
   - explicitly increase no-action budget for this scenario via `setNoActionBudget(n)`.
 - Example (read -> chat report):
   - Turn A: `const inv = query.inventory().summary(); inv`
-  - Turn B: `const inv = prevRun.returnValue; const text = Array.isArray(inv) && inv.length ? inv.map(({ name, count }) => `${count} ${name}`).join(", ") : "nothing"; await chat({ message: `I have: ${text}`, feedback: false })`
+  - Turn B: `const inv = prevRun.returnRaw; const text = Array.isArray(inv) && inv.length ? inv.map(({ name, count }) => `${count} ${name}`).join(", ") : "nothing"; await chat({ message: `I have: ${text}`, feedback: false })`
+  - Turn B (raw -> explicit stringify): `const coords = prevRun.returnRaw; await chat({ message: Array.isArray(coords) ? JSON.stringify(coords) : "[]", feedback: false })`
 
 # Response Format
 You must respond with JavaScript only (no markdown code fences).