Platform Extension MOIM (Minus One Info Message)

[tlongwell-block]

Implements ephemeral context injection at the agent boundary to automatically include timestamp and TODO content in LLM context without modifying conversation history.

Problem

Previously, accessing TODO content required explicit todo__read tool calls, cluttering conversation history and consuming tokens. Timestamps were injected via template variables in system prompts, creating inconsistency across different prompt variants and preventing effective prompt caching.

Solution

MOIM (Minus One Info Message) injects contextual information directly into the recent context during agent message preparation. This injection contains:

• Current timestamp (always)
• TODO content from session metadata (when available)
• Any other extension-provided context via the get_moim() trait method

The injection happens in agent.rs at the message preparation stage, ensuring the context is included in the LLM call but never persisted to storage or returned in conversation history.

Architecture Benefits

• Zero changes to core data structures (Message, Conversation)
• No persistence layer modifications
• Clean extension boundaries via the get_moim() trait method
• No impact on existing sessions or conversation replay
• Extensions can opt-in to MOIM by implementing the trait method

Implementation Details

• ExtensionManager::collect_moim() aggregates MOIM content from all active extensions
• moim::inject_moim() injects collected MOIM into context
• TODO extension implements get_moim() to provide task content
• Timestamp injection moved from template variables to MOIM system

Testing

Comprehensive test coverage in crates/goose/tests/moim_tests.rs with proper test isolation using serial_test for tests that modify environment variables.

Migration

• Removed todo__read tool (breaking change for recipes using it)
• Updated todo__write description to reflect automatic availability
• System prompts now receive timestamp via MOIM instead of template variables
• Removed {{current_date_time}} template variable from system prompts

User Impact

• TODO content is now automatically available in context after writing
• No need to explicitly read TODO content, reducing token usage
• Cleaner conversation history without repetitive read operations
• Consistent timestamp availability across all prompt variants

[tlongwell-block]

• I think you shouldn't bother with finding an insertion point. you are doing this just before sending it to the provider which means that if you make a mistake we'll get a catastrophic error. I think you want to prefix this to the user message just after:

if let Some(session_config) = &session {

block. that way it doesn't go to the storage, but you also don't change the structure of the conversation. you probably don't need a moim.rs then either

Unfortunately, counting on the user message would make this useless for recipes. Long-context independent work is where Goose needs this feature the most

[michaelneale]

if this is adjusting the system message each time - doesn't that mean that there is no prompt caching? (as right at the start the content diverges?) - or do I misunderstand?

[DOsinga]

if this is adjusting the system message each time - doesn't that mean that there is no prompt caching? (as right at the start the content diverges?) - or do I misunderstand?

instead of doing that, it is trying to add a synthetic message to the conversation with changeable info towards the bottom of the conversation.

[github-actions[bot]]

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[tlongwell-block]

@DOsinga can you take a look again? Think I hit your changes

Though, through benchmarking, I found I had to make the message positioning slightly more complicated again in order to get the best results. But just a little

[blackgirlbytes]

hmm, wondering why my team got tagged in this. i dont see any docs changes

[tlongwell-block]

hmm, wondering why my team got tagged in this. i dont see any docs changes

My bad! I didn't merge main in correctly earlier and a change in the docs auto tagged your team in