fix(local-asr): 修 PR #262 review 提的两个 bug

[appergb]

User description

这个 PR 做什么

跟进 PR #262 的 PR Reviewer Guide 提的两个真 bug。

Bug 1 — 小文件 retry 污染

位置：asr/local/download.rs::try_download_range_append

症状：小文件（≤32MB）路径用 append 模式打开 .partial。若上一次 attempt 写了 N 字节后断流，retry 拿到的还是完整 chunk → append → .partial 比应有大小多 N 字节，永久损坏且哨兵 .openless-asr-ready 写完后 qwen_load 仍会失败。

修法：每次 attempt 用 truncate(effective_start) + seek 重写，干净起点。小文件每个 chunk 就是整个文件，重写无成本。

Bug 2 — 多文件并发一个失败不 abort 其它 worker

位置：asr/local/download.rs::run_download 主 join 循环

症状：原代码 "signaling others to stop" 只是 log，没真 set cancel flag。某文件持久失败时，剩下的 worker 继续吃带宽直到全部完成才冒错误，浪费用户几分钟。

修法：错误时主动 cancel.store(true)；外层加 self_aborted 标记区分 "用户主动 cancel" vs "我们因错误自 abort"——前者 emit Cancelled，后者 emit Failed，不会把错误误报成用户取消。

Test plan

• cargo check 全绿
• 故意配错 mirror 触发 Bug 2 → 期望 emit Failed 而非 Cancelled，剩余 worker 立即停
• 小文件下载到一半 kill app → 重启再下 → 期望文件大小匹配 HF 报告值（不会膨胀）
• 用户中途点取消 → 期望 emit Cancelled（不要被误判 Failed）

🤖 Generated with Claude Code

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PR Type

Bug fix

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Description

• Fix retry corruption on small files by switching from append to truncate+seek

• Make any download worker failure immediately abort all parallel workers and report the error

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File Walkthrough

Relevant files

Bug fix

download.rs Fix retry corruption and abort parallel download workers on error openless-all/app/src-tauri/src/asr/local/download.rs In try_download_range_append, open the partial file with .write(true) instead of .append(true), then truncate to effective_start and seek to that position before writing the chunk. This prevents file size inflation when a retry writes the full chunk again over a partially written file. In run_download, when any per‑file worker fails, set the shared cancel flag and record self_aborted = true. The final result now correctly emits Failed rather than Cancelled, and other workers stop immediately instead of wasting bandwidth. +22/-7

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[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 262 - Partially compliant Compliant requirements: 小文件 retry 时改为按起点截断并重写，避免 .partial 膨胀损坏。 worker 失败时会主动设置 cancel flag，促使其它 worker 退出。 将用户取消与自我中止区分开，错误场景不再误报为 Cancelled。 Non-compliant requirements: 无法仅通过代码审查确认运行时行为是否与预期完全一致。 Requires further human verification: 需要在实际下载场景中验证：错误镜像触发时是否会立刻停止其它 worker，并正确上报 Failed。 需要在实际断点续传场景中验证：小文件中断后重试，.partial 大小是否始终与远端一致。 需要在实际交互中验证：用户手动取消时是否始终上报 Cancelled，且不会被误判为失败。

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ No major issues detected