[BUG] stopWhen/processInputStep receives empty content/toolResults when observationalMemory is enabled (multi-turn, multi-tool last step)

Author: zengyun261Created Sep 16, 2026Updated Sep 17, 2026

LabelsbugAgentsMemoryimpact:mediumeffort:mediumin-triage@mastra/core

Describe the Bug

StepResult.content and StepResult.toolResults are empty inside the stopWhen callback when observationalMemory is enabled on the Memory instance. With observationalMemory disabled, the same agent and prompts work correctly. This makes it impossible to inspect tool results (e.g., endTurn returning stopped) to decide whether to stop the loop.

This bug is 100% reproducible when observationalMemory is enabled.

Version: @mastra/core 1.67

typescript

memory: new Memory({
    options: {
      observationalMemory: {
        enabled: true,
      }
    },
  }),

Confirmed this still reproduces with:

@mastra/core 1.68.0-alpha.2

@mastra/memory 1.31.0-alpha.1

Same reproduction steps and same output (lastStep.content.length:0) with observationalMemory enabled. Disabling it still works. So whatever fix landed between 1.67 and these alpha versions does not cover the observationalMemory + multi-turn + multi-tool scenario.

Steps To Reproduce

bun run src/mastra/index.ts
Input hello, press Enter
Input ok, press Enter
Press Enter directly (empty input)

output(Last turn, when observationalMemory enabled):

======= stopWhen =======
lastStep.content.length:0

Link to Minimal Reproducible Example

https://github.com/zengyun261/bug-reproduction

Expected Behavior

======= stopWhen =======
lastStep.content.length:5
tool-result:sendMessage,{"type":"text","value":"ok"}
tool-result:endTurn,{"type":"json","value":{"status":"stopped"}}

Environment Information

bash

System:
    OS: macOS 26.6.2
    CPU: (18) arm64 Apple M5 Max
    Memory: 2.53 GB / 48.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.16.0 - /Users/zcloud/.nvm/versions/node/v24.16.0/bin/node
    npm: 11.13.0 - /Users/zcloud/.nvm/versions/node/v24.16.0/bin/npm
    pnpm: 12.3.4 - /Users/zcloud/Library/pnpm/bin/pnpm
    bun: 1.3.14 - /Users/zcloud/.bun/bin/bun
    Deno: 2.8.2 - /opt/homebrew/bin/deno
  Browsers:
    Chrome: 152.0.7977.83
    Safari: 26.6.2
  npmPackages:
    @mastra/core: 1.67.0 => 1.67.0 
    @mastra/duckdb: 1.9.0 => 1.9.0 
    @mastra/libsql: 1.23.0 => 1.23.0 
    @mastra/memory: 1.30.0 => 1.30.0 
    @mastra/observability: 1.17.8 => 1.17.8 
    @types/node: latest => 22.20.3 
    ai: ^7.0.103 => 7.0.103 
    mastra: 1.30.0 => 1.30.0 
    typescript: ^6.0.3 => 6.0.3 
    zod: ^4.4.3 => 4.6.5 
  npmGlobalPackages:
    @colbymchenry/codegraph: 1.4.0
    @mem0/cli: 0.2.8
    corepack: 0.35.0
    http-server: 14.1.1
    npm: 11.13.0

Verification

I have searched the existing issues to make sure this is not a duplicate
I have included sufficient information for the team to reproduce and understand the issue

Source: mastra-ai/mastra

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