CLI prompt history is global, not project-scoped

[bold84]

Bug description

The CLI TUI prompt history (arrow-up/down navigation in the input) is stored in a single global file rather than being scoped per project. This means pressing arrow-up in one project shows messages typed in completely different projects.

Steps to reproduce

1. Open opencode CLI in project A, type and send several messages
2. Close opencode
3. Open opencode CLI in project B
4. Press arrow-up in the input

Expected: See messages previously typed in project B
Actual: See messages from project A (and all other projects) mixed together

Root cause

packages/opencode/src/cli/cmd/tui/component/prompt/history.tsx:32 stores history at a global path:

const historyPath = path.join(Global.Path.state, "prompt-history.jsonl")

Global.Path.state resolves to the OS XDG state directory (~/.local/state/opencode/) which is shared across all projects. The file has no project identifier in its path, and the load/append/move functions have no project filtering.

Suggested fix

Scope the history file per project, e.g.:

const historyPath = path.join(Global.Path.state, `${projectID}`, "prompt-history.jsonl")

Or use Instance.context to derive a project-specific path rather than the global one.

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• All prompt inputs share the same history #15187: "All prompt inputs share the same history" — describes the same problem of prompt history being shared globally rather than scoped per-project/session
• tui: prompt history is clobbered w/ multiple instances of opencode #19536: "tui: prompt history is clobbered w/ multiple instances of opencode" — related issue about the shared prompt-history.jsonl file causing data loss with multiple instances

Please review those issues and consider adding your findings there if they cover the same root cause.