fix(windows): buffer streaming SendInput events

[H-Chris233]

User description

Summary

• buffer streaming insertion deltas and flush them in 12ms windows
• remove the per-character Windows SendInput delay so long transcripts do not gain linear delay
• keep streaming insertion enabled while reducing foreground app message-queue pressure

Diagnosis

Issue #491 logs show visible stalls on the Windows streaming_insert path after ASR/LLM work completes. The likely cause is rapid Unicode SendInput delivery overwhelming foreground apps such as Chromium, VSCode, Notepad3, or Explorer.

Fix

Instead of sleeping after every character, the typer now accumulates SSE deltas into a small buffer and flushes the current buffer every 12ms. This avoids 500-character transcripts gaining ~6s of artificial delay while still pacing output bursts.

Validation

• git diff --check
• cargo test --manifest-path "/home/chris233/openless/openless-all/app/src-tauri/Cargo.toml" streaming_insert -- --test-threads=1
• cargo test --manifest-path "/home/chris233/openless/openless-all/app/src-tauri/Cargo.toml" unicode_keystroke -- --test-threads=1

Follow-up

• Needs Windows real-device validation against the [windows][bug] 录音结束后总会出现明显的约5s卡顿 #491 repro apps before considering the issue fully verified.

Refs #491

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PR Type

Bug fix

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Description

• Batch streaming deltas every 12ms

• Remove Windows per-character input delay

• Reduce post-dictation UI stalls

• Preserve typed text on failures

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Diagram Walkthrough

flowchart LR
  A["Streaming SSE deltas"] --> B["mpsc buffering"]
  B -- "12ms flush window" --> C["Batch type_unicode_chunk calls"]
  C --> D["Windows SendInput"]
  D --> E["Less foreground app stalling"]

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File Walkthrough

Relevant files

Bug fix

dictation.rs Batch streaming deltas before typing                                          openless-all/app/src-tauri/src/coordinator/dictation.rs Adds a 12ms flush interval for streaming inserts Switches from unbounded async channel to blocking mpsc Buffers incoming deltas and types them in batches Extracts a helper to flush buffered text safely +64/-32  unicode_keystroke.rs Remove Windows keystroke pacing delay                                        openless-all/app/src-tauri/src/unicode_keystroke.rs Removes the 1ms sleep between Unicode keystrokes Keeps Windows SendInput delivery fully synchronous Relies on upstream batching to avoid app stalls +0/-7

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[github-actions]

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[github-actions]

Persistent review updated to latest commit 52ea7f5