feat: improve bridge context and translation decoding controls

history.md

@@ -126,3 +126,13 @@ The project now features a high-performance, Apple Silicon-optimized pipeline th
     - **Heuristic Thresholds:** Utilize `logprob_threshold` (confidence) and `compression_ratio_threshold` (repetition) to programmatically identify and discard bad transcriptions before they reach the user.
 - **Structural Features:**
     - **Word-Level Timestamps:** Enable `word_timestamps=True` to provide granular timing data for front-end caption highlighting.
+
+## Phase 16: Decoder Controls + Bridge Context Refinements
+- **Goal:** Improve English caption stability and translation quality without sacrificing runtime compatibility.
+- **Approach:**
+    - **Whisper Decoder Controls (implemented):** Added configurable decoding flags for final segments and drafts, including temperature fallback and quality thresholds (`logprob_threshold`, `compression_ratio_threshold`), with compatibility fallback when unsupported.
+    - **Beam Compatibility Hardening:** Defaulted beam sizes to greedy-safe values and auto-retry without `beam_size` when the runtime reports "Beam search decoder is not yet implemented."
+    - **Dedicated English Bridge Context:** Split context handling into source-language context and a separate English context used specifically for `task="translate"` bridge generation.
+    - **Sentence-Aware MT Chunking:** Replaced hard truncation with sentence-aware splitting for long English bridge text before translation.
+    - **Marian Generation Tuning:** Added configurable generation controls (`num_beams`, `no_repeat_ngram_size`, `length_penalty`, `repetition_penalty`, `early_stopping`) to reduce repetitive or unstable outputs.
+- **Outcome:** Better continuity for non-English to English bridging, fewer clipped translations on long segments, and cleaner target-language output with safer defaults for current `mlx_whisper` builds.