fix: integrate Agent configuration PRs and repair cross-platform validation

[ChenM0M]

Scope

Integrates the current heads of PRs #6–#32, including follow-up CI fixes. Keeps model editing, discovery errors, launch selection, draft navigation, JSONC preservation, model defaults, model disabling, capabilities, modalities, token limits, variants and effective configuration preview together.

Repairs

• Isolate synthetic-home tests from runner OpenCode environment variables; canonicalize temporary paths for macOS and Windows.
• Separate MCP cold startup budget from warm request latency; await child exit before SQLite cleanup.
• Measure dead-lock lease recovery separately from cold SQLite initialization; prepare the index before concurrent append contention.
• Resolve stacked branch conflicts without dropping either feature or its regression assertions.
• Run Agent profile behavior and locale checks in CI.

Verification so far

• Local macOS: production frontend build passed.
• Rust workspace: desktop 113 passed / 3 pre-existing ignored; CLI 10 passed; core 472 passed.
• Agent profile behavior checks, 828 contract assertions, three-locale parity, release metadata and Rust formatting passed.
• Real built CLI MCP contract passed: 39 requests; startup 770 ms; warm requests at most 392 ms.
• Browser development-fixture interaction passed: model editor scrolling; invalid token inputs; applying edits to a draft; unsaved navigation confirmation; failed persistence prevents navigation; discard allows navigation. Found and fixed an inaccessible 2210px model dialog and propagated the fix to feat(agent-profiles): 编辑变体实际参数并正确保存 (B05) #27–feat(agent-profiles): 预览配置来源、变体覆盖与启动命令 (B09) #31.
• Final local MCP run passed: 39 requests; warm maximum 328 ms; total 3320 ms.
• Schema regeneration produced no drift. Generated caches and dist were moved to macOS Trash after evidence capture; the CLI runtime and logs were retained.
• Latest CI results are being collected against exact PR head SHAs. fix(opencode): support OpenAI Responses SDK configuration (A17) #22 required one retry for an intermittent Windows RPC timeout; this history is retained. The diagnostic update logs operation names and timing while retaining the 2-second warm latency gate.

Acceptance boundary

This is a reviewable integration candidate, not a release. Windows/WSL native visible-terminal and installation acceptance still requires the target environment. CI and browser fixtures are not recorded as native acceptance. No main merge or release has been performed.

Documentation

See docs/v3/agent-config-pr-integration-20260923.md for usage changes, credential boundaries and upgrade/rollback instructions.

Final cross-platform CI audit

All 27 original PRs (#6–#32) passed Build and Test on their current head commits, and this integration candidate passed on macOS, Ubuntu and Windows at commit 8841ad85065933c9963420996d989b0776f9c01e: run 35838494343.

#22 and #28 initially had Windows MCP request timeouts and passed the same commit after one retry. #12 initially passed the code gates but its MSI bundler received an external WiX HTTP 500; the same commit passed all gates on retry. The failure history remains available in GitHub Actions.

Native Windows host/WSL and installed application acceptance against the same Release artifact/hash, including A07/E07/F07–F10/G05, remains blocked pending the target environment and release approval. This PR remains draft.