fix(think): preserve orphaned execution outcomes

[ben-reitz]

Fixes #2010.

What is the bug

Think can pause an execution while it waits for human approval. If compaction removes that execution's tool call before the approval arrives, the action still resolves, but the next model call fails because instead of saving the approval as part of the original tool call, it saves the approval as a system message in the middle of the conversation as a fallback outcome.

AI SDK v7 rejects it locally, while strict Anthropic-compatible routes return a 400 as they don't allow system messages to be inserted into the conversation mid-conversation. That message stays in history, so later turns keep failing too.

Why it happens

Normally Think replaces the paused tool result in place and continues the conversation. When the original tool part is gone, Think appends a text fallback so an already-applied approval or rejection is not silently lost.

That fallback is framework-authored, but providers cannot safely receive it as an arbitrarily placed system message.

The fix

We're keeping the same framework-authored system notes in durable session history as the fallback here, so clients and recovery logic do not mistake them for human messages.

The change is that when assembling provider messages, Think will now project recognised execution-outcome notes to ordinary user context. The same projection handles notes already stored by older Think releases without rewriting session history.

The durable-role/provider-role split is a narrow compatibility fix until Think has first-class framework events with independent storage, UI, recovery, and model projections.

Options I tried

before landing on this one:

1. store it as a user message instead of a system one - this didn't work because it then appears like a user message in the UI which means users, harness logic, and potentially models mistaking it as a user message
2. appending it to the compaction note - decided this doesn't really work for this because it needs to exist as a durable system note rather than just part of a larger compaction summary

Related issue

I think solving #1676 would give us that more holistic event model, but it will be a much larger change and needs more thought and planning. This fix solves the immediate problem.

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Latest commit: f2b5d3a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@cloudflare/think	Patch
@cloudflare/agent-think	Patch

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