inputToMastraDBMessage throws for cross-thread messages when using resource-scoped observational memory

[emekdahl]

Bug

inputToMastraDBMessage() throws Received input message with wrong threadId when an agent is called with memory that uses resource-scoped observational memory and the user has messages on multiple threads.

Reproduction

1. Configure memory with observationalMemory: { scope: "resource" } and lastMessages: 5
2. Create messages on thread A for a resource (e.g. a chat thread)
3. Call agent.generate() with memory: { thread: "thread-B", resource: "same-resource" }
4. Wait for the user to accumulate enough messages for observational memory to trigger (30k+ tokens)
5. On the next agent call, getContext() calls listMessagesByResourceId() which fetches messages from ALL threads (A and B)
6. Messages from thread A have threadId: "thread-A" but the agent expects threadId: "thread-B"
7. inputToMastraDBMessage() throws because messageSource !== "memory" and threadIds don't match

Root Cause

In @mastra/memory, getContext() at index.js:17362-17369 uses listMessagesByResourceId() when omEngine.scope === "resource" — this returns messages from all threads. But inputToMastraDBMessage() in @mastra/core at input-converter.ts validates that every non-memory message's threadId matches the agent's target thread. The retrieval and validation are incompatible.

Expected Behavior

Cross-thread messages retrieved by getContext() should either:

• Be tagged with messageSource: "memory" so they bypass the validation
• Have their threadId reassigned to the target thread
• Or the validation should be scoped to only user-provided input messages, not internally-retrieved ones

Versions

• @mastra/core: 1.23.0, 1.24.1 (confirmed present in both)
• @mastra/memory: 1.14.0, 1.15.0

Workaround

We patched inputToMastraDBMessage() to reassign message.threadId = context.memoryInfo.threadId instead of throwing.

[Magicray1217]

I'd like to work on this. Will submit a PR shortly.