feat(mac): add Qwen3 MLX streaming dictation

Replace the Sherpa offline pipeline with native MLX streaming, resilient model downloads, live transcript previews, and supporting tests and documentation.

Scripts/ensure-mlx-audio-swift.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+# Ensures vendored mlx-audio-swift is present and patched for StreamingConfig.context.
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+VENDOR="$ROOT/ThirdParty/mlx-audio-swift"
+PATCH_MARKER="$VENDOR/.osg-context-patch-applied"
+
+if [[ ! -f "$VENDOR/Package.swift" ]]; then
+  echo "Cloning mlx-audio-swift into ThirdParty/..."
+  git clone --depth 1 https://github.com/Blaizzy/mlx-audio-swift "$VENDOR"
+fi
+
+if [[ -f "$PATCH_MARKER" ]]; then
+  echo "mlx-audio-swift context patch already applied."
+  exit 0
+fi
+
+python3 <<'PY'
+from pathlib import Path
+
+root = Path("ThirdParty/mlx-audio-swift")
+manifest = root / "Package.swift"
+types = root / "Sources/MLXAudioSTT/Streaming/StreamingTypes.swift"
+session = root / "Sources/MLXAudioSTT/Streaming/StreamingInferenceSession.swift"
+
+# Pin mlx-swift to 0.31.3: 0.31.4+ adds an unconditional swift-argument-parser
+# dependency (for its `encuda` executable) that breaks offline resolution here.
+mtext = manifest.read_text()
+if "mlx-swift.git\", exact:" not in mtext:
+    mtext = mtext.replace(
+        '.package(url: "https://github.com/ml-explore/mlx-swift.git", .upToNextMajor(from: "0.30.6")),',
+        '.package(url: "https://github.com/ml-explore/mlx-swift.git", exact: "0.31.3"),',
+    )
+    manifest.write_text(mtext)
+
+text = types.read_text()
+if "public var context: String?" not in text:
+    text = text.replace(
+        "    public var language: String?\n",
+        "    public var language: String?\n"
+        "    /// Optional soft-prompt context (vocabulary / domain hints) injected into the system turn.\n"
+        "    public var context: String?\n",
+    )
+    text = text.replace(
+        "        language: String? = \"English\",\n        temperature: Float = 0.0,",
+        "        language: String? = \"English\",\n        context: String? = nil,\n        temperature: Float = 0.0,",
+    )
+    text = text.replace(
+        "        self.language = language\n        self.temperature = temperature",
+        "        self.language = language\n        self.context = context\n        self.temperature = temperature",
+    )
+    types.write_text(text)
+
+text = session.read_text()
+text = text.replace(
+    "            language: params.config.language\n        )",
+    "            context: params.config.context ?? \"\",\n            language: params.config.language\n        )",
+)
+text = text.replace(
+    "            language: config.language\n        )",
+    "            context: config.context ?? \"\",\n            language: config.language\n        )",
+)
+session.write_text(text)
+PY
+
+touch "$PATCH_MARKER"
+echo "Applied mlx-audio-swift context patch."

Scripts/generate-xcodeproj.sh

@@ -35,8 +35,12 @@ if [[ ! -f "$PRECONFIG_LOCAL" ]]; then
   echo "Edit deepseek in that file before using the local engine's built-in polish."
 fi
 
+"$ROOT/Scripts/ensure-mlx-audio-swift.sh"
+
 xcodegen generate
 
+"$ROOT/Scripts/patch-spm-local-package.sh"
+
 if python3 - "$PBXPROJ" <<'PY'
 import re
 import sys

Scripts/patch-spm-local-package.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# XcodeGen 2.43 omits `package = …` on XCSwiftPackageProductDependency for local
+# path packages, which makes Xcode show "Missing package product 'MLXAudioSTT'".
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+PBXPROJ="$ROOT/OSGKeyboard.xcodeproj/project.pbxproj"
+
+if [[ ! -f "$PBXPROJ" ]]; then
+  echo "patch-spm-local-package: $PBXPROJ not found — run xcodegen first." >&2
+  exit 1
+fi
+
+python3 - "$PBXPROJ" <<'PY'
+import re
+import sys
+from pathlib import Path
+
+path = Path(sys.argv[1])
+text = path.read_text()
+
+package_ref = re.search(
+    r'(\w+) /\* XCLocalSwiftPackageReference "ThirdParty/mlx-audio-swift" \*/ = \{\n'
+    r'\s*isa = XCLocalSwiftPackageReference;\n'
+    r'\s*relativePath = "ThirdParty/mlx-audio-swift";\n'
+    r'\s*\};',
+    text,
+)
+if not package_ref:
+    print("patch-spm-local-package: local package reference not found — skip")
+    sys.exit(0)
+
+package_id = package_ref.group(1)
+product_block = re.search(
+    r'(\w+) /\* MLXAudioSTT \*/ = \{\n'
+    r'\s*isa = XCSwiftPackageProductDependency;\n'
+    r'(\s*productName = MLXAudioSTT;\n)'
+    r'\s*\};',
+    text,
+)
+if not product_block:
+    print("patch-spm-local-package: MLXAudioSTT product dependency not found — skip")
+    sys.exit(0)
+
+product_id = product_block.group(1)
+if f"package = {package_id}" in text:
+    print("patch-spm-local-package: already patched")
+    sys.exit(0)
+
+replacement = (
+    f"{product_id} /* MLXAudioSTT */ = {{\n"
+    f"\t\t\tisa = XCSwiftPackageProductDependency;\n"
+    f"\t\t\tpackage = {package_id} /* XCLocalSwiftPackageReference \"ThirdParty/mlx-audio-swift\" */;\n"
+    f"\t\t\tproductName = MLXAudioSTT;\n"
+    f"\t\t}};"
+)
+text = text[: product_block.start()] + replacement + text[product_block.end() :]
+path.write_text(text)
+print("patch-spm-local-package: linked MLXAudioSTT → ThirdParty/mlx-audio-swift")
+PY