fix(minecraft): llm can now obtain expression results

Add rewriteTrailingExpressionToReturn helper that rewrites final non-statement expressions to return statements, apply to both normalizeReplCode and LLM planner evaluation paths to capture trailing expression values (e.g. `inv;` returns inventory array), skip rewrite if code contains explicit return/ends with block syntax/is statement keyword, add tests verifying debug REPL and multi-line LLM scripts capture trailing expression

services/minecraft/src/cognitive/conscious/brain.test.ts

@@ -72,6 +72,18 @@ function createPerceptionEvent() {
 }
 
 describe('brain no-action follow-up', () => {
+  it('returns trailing expression values in debug repl scripts', async () => {
+    const brain: any = new Brain(createDeps('await skip()'))
+
+    const result = await brain.executeDebugRepl(`
+const inv = [{ name: 'oak_sapling', count: 1 }]
+inv;
+`)
+
+    expect(result.error).toBeUndefined()
+    expect(result.returnValue).toContain('oak_sapling')
+  })
+
   it('queues exactly one synthetic follow-up on no-action result', async () => {
     const brain: any = new Brain(createDeps('1 + 1'))
     const enqueueSpy = vi.fn(async () => undefined)
@@ -88,6 +100,21 @@ describe('brain no-action follow-up', () => {
     })
   })
 
+  it('captures trailing expression return for llm multi-line scripts', async () => {
+    const brain: any = new Brain(createDeps(`
+const inv = [{ name: 'oak_sapling', count: 1 }]
+inv;
+`))
+    const enqueueSpy = vi.fn(async () => undefined)
+    brain.enqueueEvent = enqueueSpy
+
+    await brain.processEvent({} as any, createPerceptionEvent())
+
+    expect(enqueueSpy).toHaveBeenCalledTimes(1)
+    const queuedEvent = (enqueueSpy.mock.calls[0] as any[])?.[1]
+    expect(queuedEvent?.payload?.returnValue).toContain('oak_sapling')
+  })
+
   it('does not chain follow-up from follow-up event source', async () => {
     const brain: any = new Brain(createDeps('1 + 1'))
     const enqueueSpy = vi.fn(async () => undefined)

services/minecraft/src/cognitive/conscious/brain.ts

@@ -389,10 +389,44 @@ export class Brain {
   private normalizeReplCode(code: string): string {
     // Simple top-level var persistence for REPL UX:
     // const/let/var foo = ...  -> globalThis.foo = ...
-    return code.replace(
+    const normalized = code.replace(
       /^\s*(?:const|let|var)\s+([A-Za-z_$][\w$]*)\s*=\s*([^\n]+?)\s*(?:;\s*)?$/gm,
       (_full: string, name: string, valueExpr: string) => `globalThis.${name} = ${valueExpr}`,
     )
+    return this.rewriteTrailingExpressionToReturn(normalized)
+  }
+
+  private rewriteTrailingExpressionToReturn(code: string): string {
+    if (/\breturn\b/.test(code))
+      return code
+
+    const lines = code.split('\n')
+    let lastIndex = -1
+    for (let i = lines.length - 1; i >= 0; i--) {
+      if (lines[i].trim().length > 0) {
+        lastIndex = i
+        break
+      }
+    }
+
+    if (lastIndex < 0)
+      return code
+
+    const rawLine = lines[lastIndex]
+    const trimmedLine = rawLine.trim()
+    if (trimmedLine.length === 0 || trimmedLine.startsWith('//'))
+      return code
+    if (trimmedLine === '}' || trimmedLine.endsWith('{'))
+      return code
+
+    const expression = trimmedLine.replace(/;$/, '').trim()
+    const blocked = /^(?:if|for|while|switch|const|let|var|function|class|try|catch|finally|return|throw|import|export)\b/
+    if (blocked.test(expression))
+      return code
+
+    const indent = rawLine.match(/^\s*/)?.[0] ?? ''
+    lines[lastIndex] = `${indent}return (${expression})`
+    return lines.join('\n')
   }
 
   private toDebugReplActions(actions: Array<{
@@ -766,7 +800,7 @@ export class Brain {
 
       const codeToEvaluate = this.planner.canEvaluateAsExpression(result)
         ? `return (\n${result}\n)`
-        : result
+        : this.rewriteTrailingExpressionToReturn(result)
 
       const runResult = await this.planner.evaluate(
         codeToEvaluate,