bcc.py

@@ -374,6 +374,9 @@ class ServerEditor(QFrame):
         self.spawn_btn.setToolTip("Spawn the server for 3 s and report whether it starts cleanly")
         self.spawn_btn.clicked.connect(self._test_spawn)
         self.spawn_btn.setVisible(False)
+        self.logs_btn = QPushButton("View logs")
+        self.logs_btn.setToolTip("Open this server's MCP log in a read-only, auto-tailing viewer")
+        self.logs_btn.clicked.connect(self._view_logs)
         self.details_btn = QPushButton("Details ▸")
         self.details_btn.setCheckable(True)
         self.details_btn.toggled.connect(self._toggle_diag)
@@ -384,6 +387,7 @@ class ServerEditor(QFrame):
         dep.addWidget(self.fix_btn)
         dep.addWidget(self.test_btn)
         dep.addWidget(self.spawn_btn)
+        dep.addWidget(self.logs_btn)
         dep.addWidget(self.details_btn)
         dep.addWidget(recheck)
         outer.addLayout(dep)
@@ -728,6 +732,13 @@ class ServerEditor(QFrame):
         elif self.diag_card.isVisible():
             self.diag_text.setPlainText(self._full_diag_text())
 
+    def _view_logs(self):
+        name = self.current_name()
+        if not name:
+            return
+        dlg = LogViewerDialog(self.window(), name)
+        dlg.exec()
+
 
 # --------------------------------------------------------------------------- #
 # Arguments editor: one line = one argument, with a numbered gutter so that
@@ -1090,6 +1101,125 @@ class PasteDialog(QDialog):
             self.err.setText(str(e))
 
 
+# --------------------------------------------------------------------------- #
+# Log viewer dialog (issue #6): a read-only, auto-tailing view of a single
+# server's MCP log file. Polls on a QTimer instead of watching the filesystem
+# so it works the same on every platform; never writes to the log.
+# --------------------------------------------------------------------------- #
+class LogViewerDialog(QDialog):
+    POLL_MS = 1500
+    MAX_TAIL_BYTES = 300_000
+
+    def __init__(self, parent, server_name: str):
+        super().__init__(parent)
+        self._name = server_name
+        self._last_path: Path | None = None
+        self._last_size: int | None = None
+        self.setWindowTitle(f"Logs — {server_name}")
+        self.resize(760, 520)
+
+        v = QVBoxLayout(self)
+        v.setSpacing(8)
+
+        self.path_label = QLabel("")
+        self.path_label.setObjectName("muted")
+        self.path_label.setWordWrap(True)
+        v.addWidget(self.path_label)
+
+        self.view = QPlainTextEdit()
+        self.view.setObjectName("diag")
+        self.view.setReadOnly(True)
+        self.view.setLineWrapMode(QPlainTextEdit.LineWrapMode.NoWrap)
+        v.addWidget(self.view, 1)
+
+        row = QHBoxLayout()
+        self.status_label = QLabel("")
+        self.status_label.setObjectName("muted")
+        row.addWidget(self.status_label, 1)
+        refresh_btn = QPushButton("Refresh now")
+        refresh_btn.clicked.connect(self._poll)
+        row.addWidget(refresh_btn)
+        close_btn = QPushButton("Close")
+        close_btn.setObjectName("primary")
+        close_btn.clicked.connect(self.accept)
+        row.addWidget(close_btn)
+        v.addLayout(row)
+
+        self._timer = QTimer(self)
+        self._timer.setInterval(self.POLL_MS)
+        self._timer.timeout.connect(self._poll)
+        self._timer.start()
+
+        self._poll()
+
+    def _poll(self):
+        path = core.server_log_path(self._name)
+        if path is None:
+            self._last_path = None
+            self._last_size = None
+            self.path_label.setText(f"No log file for '{self._name}' yet.")
+            self.view.setPlaceholderText(
+                "No log yet — this fills in once the server has run at least once "
+                "and produced output."
+            )
+            self.view.clear()
+            self.status_label.setText("Waiting…")
+            return
+
+        self.path_label.setText(str(path))
+        try:
+            size = path.stat().st_size
+        except OSError:
+            self.status_label.setText("Log file disappeared.")
+            return
+
+        # Nothing changed since the last poll -> skip the re-read/re-render.
+        if path == self._last_path and size == self._last_size:
+            return
+
+        was_at_bottom = self._is_scrolled_to_bottom()
+        text, truncated = self._read_tail(path)
+        self.view.setPlainText(text)
+        self.status_label.setText(
+            f"Showing last {self.MAX_TAIL_BYTES // 1000} KB of the log." if truncated else ""
+        )
+        if was_at_bottom:
+            self._scroll_to_bottom()
+
+        self._last_path = path
+        self._last_size = size
+
+    def _read_tail(self, path: Path) -> tuple[str, bool]:
+        try:
+            size = path.stat().st_size
+            with open(path, "rb") as f:
+                truncated = size > self.MAX_TAIL_BYTES
+                if truncated:
+                    f.seek(size - self.MAX_TAIL_BYTES)
+                data = f.read()
+        except OSError as e:
+            return f"(could not read log: {e})", False
+        text = data.decode("utf-8", errors="replace")
+        if truncated:
+            nl = text.find("\n")
+            if nl != -1:
+                text = text[nl + 1 :]
+            text = "… (earlier lines truncated) …\n" + text
+        return text, truncated
+
+    def _is_scrolled_to_bottom(self) -> bool:
+        sb = self.view.verticalScrollBar()
+        return sb.value() >= sb.maximum() - 4
+
+    def _scroll_to_bottom(self):
+        sb = self.view.verticalScrollBar()
+        sb.setValue(sb.maximum())
+
+    def closeEvent(self, event):
+        self._timer.stop()
+        super().closeEvent(event)
+
+
 # --------------------------------------------------------------------------- #
 # Main window
 # --------------------------------------------------------------------------- #