feat(protocol): enhance raw capture functionality and documentation updates

- Update `s3_bridge.py` to default raw capture file paths to "auto" for timestamped naming.
- Modify `gui_bridge.py` to pre-check raw capture options and streamline path handling.
- Extend `ach_server.py` to save both incoming and outgoing raw bytes for analysis.
- Revise `CHANGELOG.md` and `instantel_protocol_reference.md` to reflect changes in recording mode handling and compliance data encoding.

bridges/gui_bridge.py

@@ -58,16 +58,24 @@ class BridgeGUI(tk.Tk):
         tk.Entry(self, textvariable=self.logdir_var, width=24).grid(row=1, column=3, sticky="we", **pad)
         tk.Button(self, text="Browse", command=self._choose_dir).grid(row=1, column=4, sticky="w", **pad)
 
-        # Row 2: Raw taps
-        self.raw_bw_var = tk.StringVar(value="")
-        self.raw_s3_var = tk.StringVar(value="")
-        tk.Checkbutton(self, text="Save BW->S3 raw", command=self._toggle_raw_bw, onvalue="1", offvalue="").grid(row=2, column=0, sticky="w", **pad)
-        tk.Entry(self, textvariable=self.raw_bw_var, width=28).grid(row=2, column=1, columnspan=3, sticky="we", **pad)
-        tk.Button(self, text="...", command=lambda: self._choose_file(self.raw_bw_var, "bw")).grid(row=2, column=4, **pad)
+        # Row 2: Raw taps — ON by default; "auto" = timestamped name; blank checkbox = disabled
+        self.raw_bw_enabled = tk.IntVar(value=1)
+        self.raw_s3_enabled = tk.IntVar(value=1)
+        # Path fields: empty means "auto" (bridge picks a timestamped name)
+        self.raw_bw_path_var = tk.StringVar(value="")
+        self.raw_s3_path_var = tk.StringVar(value="")
 
-        tk.Checkbutton(self, text="Save S3->BW raw", command=self._toggle_raw_s3, onvalue="1", offvalue="").grid(row=3, column=0, sticky="w", **pad)
-        tk.Entry(self, textvariable=self.raw_s3_var, width=28).grid(row=3, column=1, columnspan=3, sticky="we", **pad)
-        tk.Button(self, text="...", command=lambda: self._choose_file(self.raw_s3_var, "s3")).grid(row=3, column=4, **pad)
+        tk.Checkbutton(self, text="BW→S3 raw (auto)", variable=self.raw_bw_enabled,
+                       command=self._toggle_raw_bw).grid(row=2, column=0, sticky="w", **pad)
+        tk.Entry(self, textvariable=self.raw_bw_path_var, width=28,
+                 fg="grey").grid(row=2, column=1, columnspan=3, sticky="we", **pad)
+        tk.Button(self, text="...", command=lambda: self._choose_file(self.raw_bw_path_var, "bw")).grid(row=2, column=4, **pad)
+
+        tk.Checkbutton(self, text="S3→BW raw (auto)", variable=self.raw_s3_enabled,
+                       command=self._toggle_raw_s3).grid(row=3, column=0, sticky="w", **pad)
+        tk.Entry(self, textvariable=self.raw_s3_path_var, width=28,
+                 fg="grey").grid(row=3, column=1, columnspan=3, sticky="we", **pad)
+        tk.Button(self, text="...", command=lambda: self._choose_file(self.raw_s3_path_var, "s3")).grid(row=3, column=4, **pad)
 
         # Row 4: Status + buttons
         self.status_var = tk.StringVar(value="Idle")
@@ -102,13 +110,11 @@ class BridgeGUI(tk.Tk):
             var.set(filename)
 
     def _toggle_raw_bw(self) -> None:
-        if not self.raw_bw_var.get():
-            # default name
-            self.raw_bw_var.set(os.path.join(self.logdir_var.get(), "raw_bw.bin"))
+        # Checkbox toggled — no path action needed; enabled state drives the flag.
+        pass
 
     def _toggle_raw_s3(self) -> None:
-        if not self.raw_s3_var.get():
-            self.raw_s3_var.set(os.path.join(self.logdir_var.get(), "raw_s3.bin"))
+        pass
 
     def start_bridge(self) -> None:
         if self.process and self.process.poll() is None:
@@ -126,23 +132,22 @@ class BridgeGUI(tk.Tk):
 
         args = [sys.executable, BRIDGE_PATH, "--bw", bw, "--s3", s3, "--baud", baud, "--logdir", logdir]
 
-        ts = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
+        # Raw tap flags.
+        # Checkbox on + empty path → pass "auto" (bridge generates timestamped name).
+        # Checkbox on + explicit path → pass that path.
+        # Checkbox off → pass "" to disable (overrides bridge's auto default).
+        raw_bw_explicit = self.raw_bw_path_var.get().strip()
+        raw_s3_explicit = self.raw_s3_path_var.get().strip()
 
-        raw_bw = self.raw_bw_var.get().strip()
-        raw_s3 = self.raw_s3_var.get().strip()
+        if self.raw_bw_enabled.get():
+            args += ["--raw-bw", raw_bw_explicit if raw_bw_explicit else "auto"]
+        else:
+            args += ["--raw-bw", ""]   # explicit disable
 
-        # If the user left the default generic name, replace with a timestamped one
-        # so each session gets its own file.
-        if raw_bw:
-            if os.path.basename(raw_bw) in ("raw_bw.bin", "raw_bw"):
-                raw_bw = os.path.join(os.path.dirname(raw_bw) or logdir, f"raw_bw_{ts}.bin")
-                self.raw_bw_var.set(raw_bw)
-            args += ["--raw-bw", raw_bw]
-        if raw_s3:
-            if os.path.basename(raw_s3) in ("raw_s3.bin", "raw_s3"):
-                raw_s3 = os.path.join(os.path.dirname(raw_s3) or logdir, f"raw_s3_{ts}.bin")
-                self.raw_s3_var.set(raw_s3)
-            args += ["--raw-s3", raw_s3]
+        if self.raw_s3_enabled.get():
+            args += ["--raw-s3", raw_s3_explicit if raw_s3_explicit else "auto"]
+        else:
+            args += ["--raw-s3", ""]   # explicit disable
 
         try:
             self.process = subprocess.Popen(