fix: reconcile historical follow-up input mirrors

[4pmtong]

Pull Request

Related Issue

Description

Cloud history can replay a legacy confirmed step before canonical Run hydration supplies the same admitted user.message. That sequence rendered the user's failed follow-up twice in the transcript.

Historical Cloud playback normalizes confirmed frames to legacy.step with legacyStep: confirmed, while the local journal writes legacy.confirmed. Presentation previously recognized only the latter. Now a canonical user.message owns every confirmed mirror of its Run, in either form, keyed by Project and Run. This follows design 19 §7: legacy.confirmed is only a read-only fallback for Runs with no canonical input. Ownership is per Run and does not compare content or message identity, so a resume instruction echoed into a resumed Run as confirmed stays hidden. Legacy-only history, other Runs, other Projects, human_reply, and optimistic queries are unaffected. Raw events and persistence remain unchanged; the rule is confined to transcript presentation.

The original live v1.0.4 queued-to-403 report is still under investigation. This PR fixes the independently reproduced Cloud-history playback plus canonical-hydration duplicate.

Testing Evidence (REQUIRED)

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• No frontend/UI changes in this PR.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Contribution Guidelines Acknowledgement

• I have read and agree to the Eigent Contribution Guideline