feat(tui): live Markdown rendering during text streaming (v0.9.0)

Replaces v0.8.2's drop-Markdown patch with proper in-place Markdown
rendering. The transcript becomes a VerticalScroll container; each
turn's response body lives as a single Static widget whose content
is updated as Text deltas arrive — Markdown is re-rendered in place
rather than re-printed on Done. Eliminates the v0.8.x double-print
without sacrificing rich formatting.

- transcript: RichLog → VerticalScroll (#transcript-scroll)
- Text deltas: mount Static(Markdown(buffer)) on first delta;
  Static.update(Markdown(buffer)) on subsequent deltas
- --raw mode: bypass Markdown, mount Static(plain_str) for the same
  in-place update semantics
- Terminal events (Done/Error/Cancelled) mount styled label Statics
- _cancel_via_sse: write → mount Static on the new container
- _write_turn_headers: transcript gets a styled RichText Static
  ("── turn N ──"); other panes still receive Rule renderables
- Test suite reshape: bulk rename `log` → `transcript` for the
  presenter contract, `_mounted_renderables` helper extracts
  Static.content for assertion, `_spy_writes` captures both
  RichLog.write and VerticalScroll.mount

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.8.2"
+version = "0.9.0"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"

src/ratatoskr/tui.py

@@ -16,7 +16,7 @@ from typing import ClassVar, Literal
 import httpx
 from textual.app import App, ComposeResult
 from textual.binding import Binding
-from textual.containers import Horizontal, Vertical
+from textual.containers import Horizontal, Vertical, VerticalScroll
 from textual.theme import Theme
 from textual.widgets import (
     Footer,
@@ -194,20 +194,20 @@ class TuiPresenterState:
     # only on `\n` boundaries (one written line per natural paragraph) or
     # when the run closes (any leftover tail).
     thinking_chunk_buffer: str = ""
-    # v0.8.1: same pattern for Text deltas. Pre-v0.8.1 the Text deltas
-    # streamed into a dedicated #current-text Static below the transcript;
-    # that Static (docked-bottom, height: auto) grew during streaming and
-    # visually OVERLAPPED the transcript above (Textual didn't dynamically
-    # resize the 1fr transcript while the dock-bottom child expanded).
-    # The Static is gone in v0.8.1 — Text deltas coalesce on `\n` and write
-    # directly to `log` (transcript), the same shape thinking uses.
+    # v0.9.0: Text accumulator for live Markdown rendering. Worldtree emits
+    # Text deltas at token granularity; each delta appends to this buffer
+    # and the current_response_widget re-renders Markdown(text_chunk_buffer)
+    # in place. On terminal event the widget is finalized + reference clears.
     text_chunk_buffer: str = ""
+    # v0.9.0: reference to the Static widget holding the current turn's
+    # response Markdown Renderable. None between turns.
+    current_response_widget: object = None
 
     def render(
         self,
         event: Event,
         *,
-        log: RichLog,
+        transcript: "VerticalScroll",
         tools_log: RichLog,
         debug_log: RichLog,
         thinking_log: RichLog,
@@ -215,14 +215,14 @@ class TuiPresenterState:
     ) -> None:
         """Render one Worldtree SSE event with the TUI hierarchy + coalescing.
 
-        v0.8.1 routing:
-          - `log` (transcript) = chat content: user-prompt echo (written
-            outside the presenter), coalesced Text deltas, terminal labels,
-            optional post-Done Markdown body.
-          - `tools_log` = ToolStart + ToolResult.
-          - `debug_log` = WorkerPhase + TextBoundary.
-          - `thinking_log` = streaming Thinking deltas inline (coalesced on
-            `\n`). Rule(start)/Rule(end) wrap each run.
+        v0.9.0 routing:
+          - `transcript` (VerticalScroll) = chat content: each turn mounts
+            child widgets (turn-header / prompt-echo / response Markdown /
+            done-label). Live Markdown rendering during Text streaming.
+          - `tools_log` (RichLog) = ToolStart + ToolResult.
+          - `debug_log` (RichLog) = WorkerPhase + TextBoundary.
+          - `thinking_log` (RichLog) = streaming Thinking deltas inline
+            (coalesced on `\n`); Rule(start)/Rule(end) wrap each run.
 
         Exceptions caught at the presenter boundary (INV-009 fallback).
         """
@@ -288,47 +288,73 @@ class TuiPresenterState:
                 # coalesced on `\n`. Same pattern as Thinking (v0.7.1).
                 # The pre-v0.8.1 #current-text Static is gone — its dock-
                 # bottom growth was overlapping the transcript visually.
+                #
+                # v0.9.0: Text deltas accumulate in text_chunk_buffer and
+                # the current_response_widget renders Markdown(buffer) in
+                # place. First Text delta of the turn mounts a fresh Static
+                # holding the Markdown Renderable; subsequent deltas update
+                # the same widget. Live markdown rendering — no post-Done
+                # re-render needed.
+                from rich.markdown import Markdown
+
                 self.text_chunk_buffer += event.content
-                while "\n" in self.text_chunk_buffer:
-                    line, _, rest = self.text_chunk_buffer.partition("\n")
-                    if line:
-                        log.write(line)
-                    self.text_chunk_buffer = rest
+                # --raw bypasses Markdown rendering — useful for debugging
+                # the raw text stream surface, and matches the pre-v0.9.0
+                # --raw semantics (which dropped the post-Done Markdown re-
+                # render). In raw mode the response widget holds plain str.
+                rendered = (
+                    self.text_chunk_buffer if raw else Markdown(self.text_chunk_buffer)
+                )
+                if self.current_response_widget is None:
+                    self.current_response_widget = Static(
+                        rendered, classes="response-md"
+                    )
+                    transcript.mount(self.current_response_widget)
+                else:
+                    self.current_response_widget.update(rendered)
+                transcript.scroll_end(animate=False)
                 return
             if isinstance(event, (Done, Error, Cancelled)):
-                # Terminal event: flush any remaining text tail before the
-                # label / Markdown body lands.
-                if self.text_chunk_buffer:
-                    log.write(self.text_chunk_buffer)
-                    self.text_chunk_buffer = ""
-                # Terminal labels tinted per outcome (Aurora green / Dawn red
-                # / Dawn yellow) for at-a-glance scanning.
+                # Terminal event: finalize the response widget (clear ref so
+                # the next turn mounts a fresh one). The accumulated text is
+                # already rendered as Markdown in the widget — no post-Done
+                # re-render, no double-print.
+                self.text_chunk_buffer = ""
+                self.current_response_widget = None
+                # Terminal labels mount as styled Statics. Tinted per outcome
+                # (Aurora green / Dawn red / Dawn yellow) for at-a-glance
+                # scanning.
                 if isinstance(event, Done):
-                    log.write(RichText(
-                        f"[done] turn_id={event.sse_id.turn_id} model={event.model} "
-                        f"duration={_format_duration_ms(event.duration_ms)} "
-                        f"usage {_format_usage(event.usage, arrow='→')}",
-                        style=_AU_SUCCESS,
+                    transcript.mount(Static(
+                        RichText(
+                            f"[done] turn_id={event.sse_id.turn_id} "
+                            f"model={event.model} "
+                            f"duration={_format_duration_ms(event.duration_ms)} "
+                            f"usage {_format_usage(event.usage, arrow='→')}",
+                            style=_AU_SUCCESS,
+                        ),
+                        classes="done-label",
                     ))
-                    # v0.8.2: post-Done Markdown body re-render dropped. Pre-
-                    # v0.8.2 the transcript got BOTH the streamed text AND
-                    # the Markdown(response) re-render — same content twice,
-                    # operator-flagged as "double prints". The streamed text
-                    # IS the response now; markdown formatting (bold, lists,
-                    # code) renders as plain text. Matches thinking pane's
-                    # stream-as-content semantics (no post-close re-render).
                 elif isinstance(event, Error):
-                    log.write(RichText(
-                        f"[error] turn_id={event.sse_id.turn_id} code={event.error_code} "
-                        f"message={event.message!r}",
-                        style=_AU_ERROR,
+                    transcript.mount(Static(
+                        RichText(
+                            f"[error] turn_id={event.sse_id.turn_id} "
+                            f"code={event.error_code} message={event.message!r}",
+                            style=_AU_ERROR,
+                        ),
+                        classes="error-label",
                     ))
                 else:  # Cancelled
-                    log.write(RichText(
-                        f"[cancelled] turn_id={event.turn_id} reason={event.reason!r} "
-                        f"partial_message_id={event.partial_message_id}",
-                        style=_AU_WARNING,
+                    transcript.mount(Static(
+                        RichText(
+                            f"[cancelled] turn_id={event.turn_id} "
+                            f"reason={event.reason!r} "
+                            f"partial_message_id={event.partial_message_id}",
+                            style=_AU_WARNING,
+                        ),
+                        classes="cancelled-label",
                     ))
+                transcript.scroll_end(animate=False)
                 return
             if isinstance(event, WorkerPhase):
                 # v0.5.0: telemetry → Debug pane, not transcript.
@@ -360,22 +386,24 @@ class TuiPresenterState:
             # the original event AND a render_error line with the class name only
             # (NO exception message — security clause). Volva F1 fix.
             #
-            # v0.6.0 routing-under-failure preservation — fallback writes go
-            # to the same destination the successful render would have used:
-            #   - ToolStart/ToolResult       → tools_log
-            #   - Thinking                   → thinking_log
-            #   - WorkerPhase/TextBoundary   → debug_log
-            #   - everything else            → log
+            # v0.9.0 routing-under-failure: panes (RichLog) still write Strip
+            # lines; transcript (VerticalScroll) mounts a Static instead.
             if isinstance(event, (ToolStart, ToolResult)):
-                target = tools_log
+                tools_log.write(_plain_label(event))
+                tools_log.write(f"[render_error] {type(exc).__name__}")
             elif isinstance(event, Thinking):
-                target = thinking_log
+                thinking_log.write(_plain_label(event))
+                thinking_log.write(f"[render_error] {type(exc).__name__}")
             elif isinstance(event, (WorkerPhase, TextBoundary)):
-                target = debug_log
+                debug_log.write(_plain_label(event))
+                debug_log.write(f"[render_error] {type(exc).__name__}")
             else:
-                target = log
-            target.write(_plain_label(event))
-            target.write(f"[render_error] {type(exc).__name__}")
+                # Transcript-bound event (Text / Done / Error / Cancelled).
+                transcript.mount(Static(_plain_label(event), classes="error-label"))
+                transcript.mount(
+                    Static(f"[render_error] {type(exc).__name__}", classes="error-label")
+                )
+                transcript.scroll_end(animate=False)
 
 
 class AgentPickerApp(App[str | None]):
@@ -564,11 +592,40 @@ class RatatoskrApp(App[int]):
     }
     /* v0.6.5: thinking-current Static removed; thinking now streams
        directly into thinking-log so the whole pane scrolls naturally. */
-    #transcript {
+    /* v0.9.0: transcript is a VerticalScroll container holding dynamically
+       mounted Statics + Markdown widgets per turn. Live Markdown rendering
+       replaces the v0.8.x RichLog approach which couldn't render Markdown
+       in-flight (only on Done as a re-render → double-print bug). */
+    #transcript-scroll {
         height: 1fr;
         background: $background;
         padding: 0 1;
     }
+    /* Per-turn mounted widgets carry id-prefix conventions:
+       - .turn-header   "── turn N ──" (dim)
+       - .prompt-echo   "❯ user input"  (aurora bright cyan)
+       - .response-md   Markdown(accumulated_text) — updated live
+       - .done-label    "[done] turn_id=…" (aurora green)
+       - .error-label   "[error] …"        (dawn red)
+       - .cancelled-label "[cancelled] …"  (dawn yellow)
+    */
+    .turn-header {
+        height: auto;
+        padding: 0 1;
+        color: $au-dark-60;
+    }
+    .prompt-echo {
+        height: auto;
+        padding: 0 1;
+    }
+    .response-md {
+        height: auto;
+        padding: 0 1;
+    }
+    .done-label, .error-label, .cancelled-label {
+        height: auto;
+        padding: 0 1;
+    }
     /* v0.8.1: #current-text Static removed. Streaming text now coalesces
        on `\n` and writes directly to #transcript (same pattern as v0.7.1
        thinking fix). Eliminates the dock-bottom-growth-overlap bug. */
@@ -670,7 +727,12 @@ class RatatoskrApp(App[int]):
         # work without widget-level markup=True.
         with Horizontal(id="main-row"):
             with Vertical(id="left-column"):
-                yield RichLog(id="transcript", wrap=True, markup=False, highlight=False)
+                # v0.9.0: transcript is a VerticalScroll holding per-turn
+                # mounted widgets (turn header, prompt echo, response Markdown,
+                # done label). Live Markdown rendering happens via Static
+                # widgets holding `Markdown` Renderables, updated as Text
+                # deltas arrive.
+                yield VerticalScroll(id="transcript-scroll")
                 yield Input(id="prompt", placeholder="Type a message and press Enter")
             with Vertical(id="right-column"):
                 with TabbedContent(id="side-panes"):
@@ -733,20 +795,30 @@ class RatatoskrApp(App[int]):
         self._set_hint(self.HINT_IDLE)
 
     def _write_turn_headers(self, turn_id: int) -> None:
-        """v0.6.0: Write `── turn N ──` Rule headers across every pane so
-        operators can visually correlate sections during cross-pane
-        debugging. Called from `_stream_turn_worker` on first event of
-        each new turn (idempotent per turn via active_turn_id guard).
+        """v0.6.0: turn-ID headers across every pane for cross-pane
+        correlation. v0.9.0: transcript is a VerticalScroll; mounts a
+        Static with rule-style text instead of writing a Rule Renderable
+        to RichLog. Other panes still use RichLog.write(Rule).
         """
         from rich.rule import Rule
+        from rich.text import Text as RichText
 
         title = f"turn {turn_id}"
         rule = Rule(title=title, style=_AU_DEMOTED)
         try:
-            self.query_one("#transcript", RichLog).write(rule)
+            # Transcript (VerticalScroll): mount a styled Static.
+            transcript = self.query_one("#transcript-scroll", VerticalScroll)
+            transcript.mount(
+                Static(
+                    RichText(f"── turn {turn_id} ──", style=_AU_DEMOTED),
+                    classes="turn-header",
+                )
+            )
+            # Other panes (RichLog): write the Rule Renderable.
             self.query_one("#tools-log", RichLog).write(rule)
             self.query_one("#debug-log", RichLog).write(rule)
             self.query_one("#thinking-log", RichLog).write(rule)
+            transcript.scroll_end(animate=False)
         except Exception:
             # Defensive: widget tree may be tearing down — never let a
             # turn-header write block the SSE consumer.
@@ -762,12 +834,19 @@ class RatatoskrApp(App[int]):
             pass
 
     async def on_input_submitted(self, event: Input.Submitted) -> None:
-        """Echo user prompt, spawn stream worker; busy notice if not idle."""
+        """Echo user prompt, spawn stream worker; busy notice if not idle.
+
+        v0.9.0: prompt echo mounts as a Static in the transcript VerticalScroll
+        (was log.write to RichLog).
+        """
         if event.input.id != "prompt":
             return
-        log = self.query_one("#transcript", RichLog)
+        transcript = self.query_one("#transcript-scroll", VerticalScroll)
         if self.state != "idle":
-            log.write("[busy] turn in flight; input ignored")
+            transcript.mount(
+                Static("[busy] turn in flight; input ignored", classes="error-label")
+            )
+            transcript.scroll_end(animate=False)
             event.input.value = ""
             return
         content = event.input.value.strip()
@@ -776,7 +855,13 @@ class RatatoskrApp(App[int]):
         # v0.4.1 retheme: operator's voice gets Australis bright cyan so it
         # stands out against the default-foreground assistant text below it.
         from rich.text import Text as RichText
-        log.write(RichText(f"❯ {content}", style=_AU_USER_ECHO))  # noqa: RUF001
+        transcript.mount(
+            Static(
+                RichText(f"❯ {content}", style=_AU_USER_ECHO),  # noqa: RUF001
+                classes="prompt-echo",
+            )
+        )
+        transcript.scroll_end(animate=False)
         event.input.value = ""
         self.state = "streaming"
         self._set_hint(self.HINT_STREAMING)
@@ -785,26 +870,37 @@ class RatatoskrApp(App[int]):
         )
 
     async def _stream_turn_worker(self, content: str) -> None:
-        """Drive stream_turn, render events via TuiPresenterState (issue #12)."""
+        """Drive stream_turn, render events via TuiPresenterState.
+
+        v0.9.0: transcript is a VerticalScroll; the presenter's `transcript`
+        argument is the container, and the presenter mounts Static / Markdown-
+        backed widgets directly. Wire-error labels mount as `error-label`
+        Statics into the transcript-scroll.
+        """
         assert self.state == "streaming"
         assert self.client is not None
         assert content
-        log = self.query_one("#transcript", RichLog)
+        transcript = self.query_one("#transcript-scroll", VerticalScroll)
         tools_log = self.query_one("#tools-log", RichLog)
         debug_log = self.query_one("#debug-log", RichLog)
         thinking_log = self.query_one("#thinking-log", RichLog)
         presenter = TuiPresenterState()
+
+        def _mount_wire_error(label: str) -> None:
+            try:
+                transcript.mount(Static(label, classes="error-label"))
+                transcript.scroll_end(animate=False)
+            except Exception:
+                pass
+
         try:
             async for event in stream_turn(self.client, self.session_id, content):
                 if self.active_turn_id is None:
                     self.active_turn_id = event.sse_id.turn_id
-                    # v0.6.0: turn-ID headers across all panes so the
-                    # operator can visually correlate sections during
-                    # cross-pane debugging.
                     self._write_turn_headers(self.active_turn_id)
                 presenter.render(
                     event,
-                    log=log,
+                    transcript=transcript,
                     tools_log=tools_log,
                     debug_log=debug_log,
                     thinking_log=thinking_log,
@@ -813,15 +909,15 @@ class RatatoskrApp(App[int]):
                 if isinstance(event, (Done, Error, Cancelled)):
                     break
         except SseConnectFailed as exc:
-            log.write(f"[sse_connect_failed] status={exc.status} body={exc.body!r}")
+            _mount_wire_error(f"[sse_connect_failed] status={exc.status} body={exc.body!r}")
         except SseConnectionDropped as exc:
-            log.write(f"[connection_dropped] last_seen={exc.last_seen_sse_id}")
+            _mount_wire_error(f"[connection_dropped] last_seen={exc.last_seen_sse_id}")
         except MalformedSseId as exc:
-            log.write(f"[malformed_sse_id] raw={exc.raw!r}")
+            _mount_wire_error(f"[malformed_sse_id] raw={exc.raw!r}")
         except MalformedSseData as exc:
-            log.write(f"[malformed_sse_data] raw={exc.raw!r}")
+            _mount_wire_error(f"[malformed_sse_data] raw={exc.raw!r}")
         except TurnIdFlip as exc:
-            log.write(f"[turn_id_flip] expected={exc.established} got={exc.got}")
+            _mount_wire_error(f"[turn_id_flip] expected={exc.established} got={exc.got}")
         finally:
             self.state = "idle"
             self.active_turn_id = None
@@ -844,9 +940,12 @@ class RatatoskrApp(App[int]):
                 return
             self.state = "cancelling"
             self._set_hint(self.HINT_CANCELLING)
-            log = self.query_one("#transcript", RichLog)
+            transcript = self.query_one("#transcript-scroll", VerticalScroll)
             self.run_worker(
-                _cancel_via_sse(self.client, self.session_id, self.active_turn_id, log=log)
+                _cancel_via_sse(
+                    self.client, self.session_id, self.active_turn_id,
+                    transcript=transcript,
+                )
             )
         elif self.state == "cancelling":
             if self.stream_worker is not None:
@@ -995,12 +1094,23 @@ async def _cancel_via_sse(
     session_id: str,
     turn_id: int,
     *,
-    log: RichLog,
+    transcript: VerticalScroll,
 ) -> None:
-    """Fire-and-forget cancel; never raises (mirrors cli._cancel_and_log; #3 INV-009)."""
+    """Fire-and-forget cancel; never raises (mirrors cli._cancel_and_log; #3 INV-009).
+
+    v0.9.0: mounts a `[cancel_failed]` Static into the transcript-scroll
+    container on failure (was log.write to RichLog).
+    """
     assert client is not None
     assert isinstance(turn_id, int) and turn_id > 0
     try:
         await cancel_turn(client, session_id, turn_id)
     except (CancelFailed, CancelTurnNotFound, CancelAlreadyCompleted, httpx.RequestError) as exc:
-        log.write(f"[cancel_failed] {type(exc).__name__}: {exc}")
+        try:
+            transcript.mount(Static(
+                f"[cancel_failed] {type(exc).__name__}: {exc}",
+                classes="error-label",
+            ))
+            transcript.scroll_end(animate=False)
+        except Exception:
+            pass

tests/test_tui.py

@@ -61,20 +61,43 @@ def _args_existing(session_id: str = "s-1existing", **overrides) -> ParsedArgs:
 
 
 def _spy_writes(monkeypatch) -> list:
-    """Patch RichLog.write to record every arg into a list (returned).
+    """Patch RichLog.write AND VerticalScroll.mount to record every renderable
+    or mounted-widget content into a single list (returned).
 
-    Accepts *args/**kwargs so Textual's internal deferred-render path
-    (which calls write positionally with width/expand/shrink/scroll_end)
-    still works after a write-during-mount + Resize sequence.
+    v0.9.0: transcript content is mounted into a VerticalScroll, not written
+    to a RichLog. The spy captures both shapes — for each mounted Static, the
+    Static's `renderable` (Markdown / RichText / str) lands in the list,
+    indistinguishably from RichLog.write entries. Integration tests assert
+    on substrings or types in `writes` so the merged shape is the right
+    abstraction.
+
+    Accepts *args/**kwargs so Textual's internal deferred-render paths still
+    work after a write-during-mount + Resize sequence.
     """
+    from textual.containers import VerticalScroll
+    from textual.widgets import Static
+
     writes: list = []
-    original = RichLog.write
 
-    def spy(self, content, *args, **kw):
+    original_write = RichLog.write
+
+    def spy_write(self, content, *args, **kw):
         writes.append(content)
-        return original(self, content, *args, **kw)
+        return original_write(self, content, *args, **kw)
 
-    monkeypatch.setattr(RichLog, "write", spy)
+    monkeypatch.setattr(RichLog, "write", spy_write)
+
+    original_mount = VerticalScroll.mount
+
+    def spy_mount(self, *children, **kw):
+        for child in children:
+            if isinstance(child, Static):
+                writes.append(child.content)
+            else:
+                writes.append(child)
+        return original_mount(self, *children, **kw)
+
+    monkeypatch.setattr(VerticalScroll, "mount", spy_mount)
     return writes
 
 
@@ -126,13 +149,13 @@ class TestTuiPresenterState:
 
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         thinking_log = MagicMock()
         state = TuiPresenterState()
         for chunk in ("Let", " me", " think"):
             state.render(
                 Thinking(sse_id=SID, content=chunk),
-                log=log,
+                transcript=transcript,
                 tools_log=MagicMock(),
                 debug_log=MagicMock(),
                 thinking_log=thinking_log,
@@ -143,7 +166,7 @@ class TestTuiPresenterState:
         assert len(writes) == 1
         assert isinstance(writes[0], Rule)
         assert state.thinking_chunk_buffer == "Let me think"
-        assert log.write.call_count == 0
+        assert transcript.mount.call_count == 0
 
     def test_thinking_flushes_on_newline(self) -> None:
         """thinking_flushes_on_newline [happy, v0.7.1]:
@@ -156,7 +179,7 @@ class TestTuiPresenterState:
         for chunk in ("Hello", " world", "\n"):
             state.render(
                 Thinking(sse_id=SID, content=chunk),
-                log=MagicMock(),
+                transcript=MagicMock(),
                 tools_log=MagicMock(),
                 debug_log=MagicMock(),
                 thinking_log=thinking_log,
@@ -178,14 +201,14 @@ class TestTuiPresenterState:
 
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         debug_log = MagicMock()
         thinking_log = MagicMock()
         state = TuiPresenterState()
         for content in ("a", "b"):
             state.render(
                 Thinking(sse_id=SID, content=content),
-                log=log,
+                transcript=transcript,
                 tools_log=MagicMock(),
                 debug_log=debug_log,
                 thinking_log=thinking_log,
@@ -193,7 +216,7 @@ class TestTuiPresenterState:
             )
         state.render(
             WorkerPhase(sse_id=SID, phase="streaming", turn_id=42),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=debug_log,
             thinking_log=thinking_log,
@@ -207,7 +230,7 @@ class TestTuiPresenterState:
         assert isinstance(thinking_writes[2], Rule)
         # worker_phase still goes to debug_log; transcript untouched.
         assert "· worker_phase:" in _text_of(debug_log.write.call_args_list[-1][0][0])
-        assert not log.write.called
+        assert not transcript.mount.called
 
     # v0.6.5: thinking-current Static removed; test_thinking_widget_truncation
     # and test_thinking_widget_visibility_lifecycle deleted (no longer apply).
@@ -224,7 +247,7 @@ class TestTuiPresenterState:
 
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         thinking_log = MagicMock()
         state = TuiPresenterState()
         for evt in (
@@ -233,13 +256,13 @@ class TestTuiPresenterState:
             Thinking(sse_id=SID, content="second"),
         ):
             state.render(
-                evt, log=log,
+                evt, transcript=transcript,
                 tools_log=MagicMock(), debug_log=MagicMock(),
                 thinking_log=thinking_log, raw=False,
             )
         state.render(
             _make_tui_done(),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(), debug_log=MagicMock(),
             thinking_log=thinking_log, raw=False,
         )
@@ -251,9 +274,9 @@ class TestTuiPresenterState:
         assert "first" in delta_strs
         assert "second" in delta_strs
         # v0.8.1: Text "hi" flushes as a line in transcript on Done.
-        log_writes = [_text_of(c[0][0]) for c in log.write.call_args_list]
-        assert "hi" in log_writes
-        assert any(w.startswith("[done]") for w in log_writes if isinstance(w, str))
+        transcript_renderables = [_text_of(r) for r in _mounted_renderables(transcript)]
+        assert "hi" in transcript_renderables
+        assert any(w.startswith("[done]") for w in transcript_renderables if isinstance(w, str))
 
     def test_render_exception_fallback(self) -> None:
         """render_exception_fallback [adversarial, v0.6.5]:
@@ -263,7 +286,7 @@ class TestTuiPresenterState:
         """
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         thinking_log = MagicMock()
         # First call (Rule write) raises; subsequent calls succeed for fallback.
         thinking_log.write.side_effect = [
@@ -274,7 +297,7 @@ class TestTuiPresenterState:
         state = TuiPresenterState()
         state.render(
             Thinking(sse_id=SID, content="x"),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(),
             thinking_log=thinking_log,
@@ -284,7 +307,7 @@ class TestTuiPresenterState:
         assert any(w.startswith("[thinking]") for w in writes), writes
         assert any(w == "[render_error] AttributeError" for w in writes), writes
         assert not any("rule write failed" in w for w in writes), writes
-        assert not log.write.called
+        assert not transcript.mount.called
 
     def test_state_reset_per_worker(self) -> None:
         """state_reset_per_worker [trace]: fresh TuiPresenterState() starts no thinking open."""
@@ -293,7 +316,7 @@ class TestTuiPresenterState:
         s1 = TuiPresenterState()
         s1.render(
             Thinking(sse_id=SID, content="x"),
-            log=MagicMock(),
+            transcript=MagicMock(),
             tools_log=MagicMock(),
             debug_log=MagicMock(),
             thinking_log=MagicMock(),
@@ -310,12 +333,12 @@ class TestTuiPresenterState:
         """
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         thinking_log = MagicMock()
         state = TuiPresenterState()
         state.render(
             Thinking(sse_id=SID, content="partial"),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(), thinking_log=thinking_log, raw=False,
         )
@@ -323,81 +346,88 @@ class TestTuiPresenterState:
             Cancelled(
                 sse_id=SID, phase="cancelled", turn_id=42, reason="user", partial_message_id=None
             ),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(), thinking_log=thinking_log, raw=False,
         )
         # v0.6.5: streamed thinking + Rule(end) in thinking_log; [cancelled] in transcript.
-        log_writes = [_text_of(c[0][0]) for c in log.write.call_args_list]
-        assert any(w.startswith("[cancelled]") for w in log_writes)
+        transcript_renderables = [_text_of(r) for r in _mounted_renderables(transcript)]
+        assert any(w.startswith("[cancelled]") for w in transcript_renderables)
         # thinking_log got at least Rule(start) + "partial" delta + Rule(end)
         assert thinking_log.write.call_count >= 3
 
-    def test_done_flushes_tail_and_writes_label(self) -> None:
-        """done_flushes_tail_and_writes_label [happy, v0.8.2]:
-        Text("hi") buffers in text_chunk_buffer (no `\\n`). Done flushes
-        "hi" tail to transcript, then writes [done] label. v0.8.2 drops
-        the post-Done Markdown body re-render — streamed text is the
-        canonical content (no double-print).
+    def test_text_then_done_mounts_widget_and_finalizes(self) -> None:
+        """text_then_done_mounts_widget_and_finalizes [happy, v0.9.0]:
+        First Text delta mounts a Static(Markdown(buffer)) into the transcript;
+        Done finalizes the widget reference and mounts a styled [done] label.
+        No duplicate content (v0.9.0 replaces v0.8.x's flush-on-Done with
+        live in-place Markdown updates).
         """
         from rich.markdown import Markdown
-        from rich.rule import Rule
 
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         state = TuiPresenterState()
         state.render(
             Text(sse_id=SID, content="hi"),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(),
             thinking_log=MagicMock(),
             raw=False,
         )
-        assert not log.write.called
+        # v0.9.0: response widget mounted on first Text delta with Markdown wrapper.
+        assert transcript.mount.called
+        first_widget = transcript.mount.call_args_list[0][0][0]
+        assert isinstance(first_widget.content, Markdown)
+        assert first_widget.content.markup == "hi"
         assert state.text_chunk_buffer == "hi"
+        # Done finalizes: text_chunk_buffer cleared, widget ref released, label mounted.
         state.render(
             _make_tui_done(),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(),
             thinking_log=MagicMock(),
             raw=False,
         )
-        # On Done: tail flush "hi" + [done] label. No Markdown, no Rule.
-        writes = [c[0][0] for c in log.write.call_args_list]
-        assert "hi" in writes
+        writes = _mounted_renderables(transcript)
         assert any(_text_of(w).startswith("[done]") for w in writes)
-        # v0.8.2: no post-Done re-render — no duplicate content.
-        assert not any(isinstance(w, Markdown) for w in writes)
-        assert not any(isinstance(w, Rule) for w in writes)
+        # v0.9.0: response Markdown rendered live during stream — only ONE
+        # Markdown renderable lands in the transcript (no post-Done re-render).
+        markdowns = [w for w in writes if isinstance(w, Markdown)]
+        assert len(markdowns) == 1
         assert state.text_chunk_buffer == ""
+        assert state.current_response_widget is None
 
     def test_raw_flag_skips_markdown(self) -> None:
-        """raw_flag_skips_markdown [trace]: raw=True → no Rule, no Markdown."""
+        """raw_flag_skips_markdown [v0.9.0]: raw=True → response widget holds
+        plain str instead of Markdown. Live in-place update still happens;
+        only the wrapper differs.
+        """
         from rich.markdown import Markdown
-        from rich.rule import Rule
 
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         state = TuiPresenterState()
         state.render(
             Text(sse_id=SID, content="hi"),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(), thinking_log=MagicMock(), raw=True,
         )
         state.render(
             _make_tui_done(),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(), thinking_log=MagicMock(), raw=True,
         )
-        writes = [c[0][0] for c in log.write.call_args_list]
-        assert not any(isinstance(w, Rule) for w in writes)
+        writes = _mounted_renderables(transcript)
+        # Raw mode bypasses Markdown entirely — content lives as plain str.
         assert not any(isinstance(w, Markdown) for w in writes)
+        assert "hi" in writes
 
     def test_worker_phase_demoted_to_debug_log(self) -> None:
         """worker_phase_demoted_to_debug_log [trace, v0.5.0]: WorkerPhase → debug_log
@@ -408,17 +438,17 @@ class TestTuiPresenterState:
 
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         debug_log = MagicMock()
         state = TuiPresenterState()
         state.render(
             WorkerPhase(sse_id=SID, phase="streaming", turn_id=42),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=debug_log, thinking_log=MagicMock(), raw=False,
         )
         # v0.5.0: WorkerPhase routes to debug_log, NOT transcript.
-        assert not log.write.called
+        assert not transcript.mount.called
         renderable = debug_log.write.call_args[0][0]
         # INV-003: must be a styled Rich Text renderable, not a plain str.
         # v0.4.1 retheme: style is now Australis Sea dark-60 ("#86929d") instead
@@ -443,12 +473,12 @@ class TestTuiPresenterState:
         """
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         tools_log = MagicMock()
         state = TuiPresenterState()
         state.render(
             ToolStart(sse_id=SID, name="read_file", arguments={"path": "/x"}),
-            log=log,
+            transcript=transcript,
             tools_log=tools_log,
             debug_log=MagicMock(), thinking_log=MagicMock(), raw=False,
         )
@@ -456,85 +486,95 @@ class TestTuiPresenterState:
         assert tools_log.write.called
         assert _text_of(tools_log.write.call_args[0][0]).startswith("· tool_start:")
         # INV-014: transcript was NOT written to
-        assert not log.write.called
+        assert not transcript.mount.called
 
     def test_tool_result_routes_to_tools_log(self) -> None:
         """tool_result_routes_to_tools_log [INV-014]: ToolResult → tools_log, NOT transcript."""
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         tools_log = MagicMock()
         state = TuiPresenterState()
         state.render(
             ToolResult(sse_id=SID, name="read_file", result="ok", duration_ms=12),
-            log=log,
+            transcript=transcript,
             tools_log=tools_log,
             debug_log=MagicMock(), thinking_log=MagicMock(), raw=False,
         )
         assert tools_log.write.called
         assert _text_of(tools_log.write.call_args[0][0]).startswith("· tool_result:")
-        assert not log.write.called
+        assert not transcript.mount.called
 
-    def test_text_event_buffers_until_newline(self) -> None:
-        """text_event_buffers_until_newline [v0.8.1]: Text deltas without
-        `\\n` accumulate in text_chunk_buffer; no log write yet.
+    def test_text_first_delta_mounts_response_widget(self) -> None:
+        """text_first_delta_mounts_response_widget [v0.9.0]: first Text delta
+        mounts a Static carrying Markdown(buffer) into the transcript. The
+        text_chunk_buffer holds the accumulated content for the next delta's
+        in-place update.
         """
+        from rich.markdown import Markdown
+
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         tools_log = MagicMock()
         state = TuiPresenterState()
         state.render(
             Text(sse_id=SID, content="hello"),
-            log=log,
+            transcript=transcript,
             tools_log=tools_log,
             debug_log=MagicMock(),
             thinking_log=MagicMock(),
             raw=False,
         )
-        # v0.8.1: buffered, not written until `\n` or Done.
         assert state.text_chunk_buffer == "hello"
-        assert not log.write.called
+        assert transcript.mount.call_count == 1
+        widget = transcript.mount.call_args[0][0]
+        assert isinstance(widget.content, Markdown)
+        assert widget.content.markup == "hello"
+        assert state.current_response_widget is widget
         assert not tools_log.write.called
 
-    def test_text_flushes_on_newline(self) -> None:
-        """text_flushes_on_newline [v0.8.1]: a delta carrying `\\n` flushes
-        the accumulated buffer as ONE line to log (transcript).
+    def test_text_subsequent_deltas_update_in_place(self) -> None:
+        """text_subsequent_deltas_update_in_place [v0.9.0]: deltas after the
+        first do NOT mount a new widget — they update the existing widget's
+        Markdown content in place. The text_chunk_buffer accumulates.
         """
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         state = TuiPresenterState()
-        for tok in ("Hel", "lo", " ", "world", "\n"):
+        for tok in ("Hel", "lo", " ", "world"):
             state.render(
                 Text(sse_id=SID, content=tok),
-                log=log,
+                transcript=transcript,
                 tools_log=MagicMock(),
                 debug_log=MagicMock(),
                 thinking_log=MagicMock(),
                 raw=False,
             )
-        writes = [c[0][0] for c in log.write.call_args_list]
-        # "Hello world" coalesces to ONE log entry.
-        assert writes == ["Hello world"]
-        assert state.text_chunk_buffer == ""
+        # Exactly ONE mount (the first delta); subsequent deltas update.
+        assert transcript.mount.call_count == 1
+        assert state.text_chunk_buffer == "Hello world"
+        # Widget reference held; buffer is the source of truth re-rendered
+        # into Markdown(...) for each Static.update call.
+        assert state.current_response_widget is not None
 
     def test_duration_format_seconds(self) -> None:
         """duration_format_seconds [trace]: Done(duration_ms=5467) → label has "duration=5.5s"."""
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         state = TuiPresenterState()
         state.render(
             _make_tui_done(duration_ms=5467),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(), thinking_log=MagicMock(), raw=True,
         )
         done_line = next(
-            _text_of(c[0][0])
-            for c in log.write.call_args_list
-            if _text_of(c[0][0]).startswith("[done]")
+            _text_of(r)
+            for r in _mounted_renderables(transcript)
+            if _text_of(r).startswith("[done]")
         )
         assert "duration=5.5s" in done_line
         assert "duration_ms=5467" not in done_line
@@ -543,7 +583,7 @@ class TestTuiPresenterState:
         """usage_format_unicode_arrow [trace]: TUI Done label uses → (Unicode), not -> (ASCII)."""
         from ratatoskr.tui import TuiPresenterState
 
-        log = MagicMock()
+        transcript = MagicMock()
         state = TuiPresenterState()
         usage = {
             "prompt_tokens": 6756,
@@ -553,14 +593,14 @@ class TestTuiPresenterState:
         }
         state.render(
             _make_tui_done(usage=usage),
-            log=log,
+            transcript=transcript,
             tools_log=MagicMock(),
             debug_log=MagicMock(), thinking_log=MagicMock(), raw=True,
         )
         done_line = next(
-            _text_of(c[0][0])
-            for c in log.write.call_args_list
-            if _text_of(c[0][0]).startswith("[done]")
+            _text_of(r)
+            for r in _mounted_renderables(transcript)
+            if _text_of(r).startswith("[done]")
         )
         assert "usage 6756 in → 126 out (6882 total, 0 cached)" in done_line
 
@@ -571,14 +611,38 @@ def _text_of(write_arg: object) -> str:
     Issue #12 wraps demoted-telemetry entries in `rich.text.Text(..., style="dim")`
     so the RichLog can apply dim styling; non-demoted writes stay as plain str.
     Tests that want to assert against content need both shapes flattened.
+
+    v0.9.0: also extracts plain text from Markdown wrappers (the streaming-text
+    response path uses Markdown(buffer) now; tests assert against the source
+    markup, which lives in `Markdown.markup`).
     """
+    from rich.markdown import Markdown
     from rich.text import Text as RichText
 
     if isinstance(write_arg, RichText):
         return write_arg.plain
+    if isinstance(write_arg, Markdown):
+        return write_arg.markup
     if isinstance(write_arg, str):
         return write_arg
-    return ""  # Markdown / Rule / etc. — not text content
+    return ""  # Rule / etc. — not text content
+
+
+def _mounted_renderables(transcript_mock: MagicMock) -> list:
+    """v0.9.0: TuiPresenterState now mounts Static widgets into the transcript
+    VerticalScroll instead of writing renderables to a RichLog. Tests using a
+    MagicMock transcript inspect `transcript.mount.call_args_list`; each call's
+    first positional arg is the Static child whose `.content` carries the
+    Markdown / RichText / str that pre-v0.9.0 would have been the write arg.
+    Returns those renderables in mount-call order so tests can assert on them
+    with the same shape they used for `log.write.call_args_list` previously.
+    """
+    out: list = []
+    for call in transcript_mock.mount.call_args_list:
+        for child in call.args:
+            renderable = getattr(child, "content", child)
+            out.append(renderable)
+    return out
 
 
 def _make_tui_done(*, duration_ms: int = 1, usage: dict[str, int] | None = None) -> Done:
@@ -602,15 +666,15 @@ def _make_tui_done(*, duration_ms: int = 1, usage: dict[str, int] | None = None)
 class TestCancelViaSse:
     @respx.mock
     async def test_happy_cancel(self) -> None:
-        """happy_cancel [happy,tracer]: 200 OK → returns None; log has no [cancel_failed]."""
+        """happy_cancel [happy,tracer]: 200 OK → returns None; transcript has no [cancel_failed]."""
         respx.post("https://w.example/sessions/s-1/turns/42/cancel").mock(
             return_value=httpx.Response(200, json=_CANCEL_OK_RESP)
         )
-        log = MagicMock()
+        transcript = MagicMock()
         async with httpx.AsyncClient(base_url="https://w.example") as client:
-            result = await _cancel_via_sse(client, "s-1", 42, log=log)
+            result = await _cancel_via_sse(client, "s-1", 42, transcript=transcript)
         assert result is None
-        log.write.assert_not_called()
+        transcript.mount.assert_not_called()
 
     @respx.mock
     async def test_cancel_failed_500(self) -> None:
@@ -618,10 +682,10 @@ class TestCancelViaSse:
         respx.post("https://w.example/sessions/s-1/turns/42/cancel").mock(
             return_value=httpx.Response(500, content=b"boom")
         )
-        log = MagicMock()
+        transcript = MagicMock()
         async with httpx.AsyncClient(base_url="https://w.example") as client:
-            await _cancel_via_sse(client, "s-1", 42, log=log)
-        line = log.write.call_args[0][0]
+            await _cancel_via_sse(client, "s-1", 42, transcript=transcript)
+        line = transcript.mount.call_args[0][0].content
         assert "[cancel_failed]" in line
         assert "CancelFailed" in line
 
@@ -631,10 +695,10 @@ class TestCancelViaSse:
         respx.post("https://w.example/sessions/s-1/turns/42/cancel").mock(
             return_value=httpx.Response(409)
         )
-        log = MagicMock()
+        transcript = MagicMock()
         async with httpx.AsyncClient(base_url="https://w.example") as client:
-            await _cancel_via_sse(client, "s-1", 42, log=log)
-        line = log.write.call_args[0][0]
+            await _cancel_via_sse(client, "s-1", 42, transcript=transcript)
+        line = transcript.mount.call_args[0][0].content
         assert "[cancel_failed]" in line
         assert "CancelAlreadyCompleted" in line
 
@@ -644,10 +708,10 @@ class TestCancelViaSse:
         respx.post("https://w.example/sessions/s-1/turns/42/cancel").mock(
             side_effect=httpx.ConnectError("network down")
         )
-        log = MagicMock()
+        transcript = MagicMock()
         async with httpx.AsyncClient(base_url="https://w.example") as client:
-            await _cancel_via_sse(client, "s-1", 42, log=log)
-        line = log.write.call_args[0][0]
+            await _cancel_via_sse(client, "s-1", 42, transcript=transcript)
+        line = transcript.mount.call_args[0][0].content
         assert "[cancel_failed]" in line
         assert "ConnectError" in line
 
@@ -714,18 +778,18 @@ class TestLayoutShape:
             assert row is not None
 
     async def test_left_column_content_only(self) -> None:
-        """left_column_content_only [v0.6.5]: left column = transcript + prompt
-        + current-text (streaming text Static). thinking-current Static
-        removed entirely as of v0.6.5.
+        """left_column_content_only [v0.9.0]: left column = transcript-scroll
+        VerticalScroll + prompt Input. thinking-current Static removed in
+        v0.6.5; transcript RichLog replaced by VerticalScroll in v0.9.0.
         """
-        from textual.containers import Vertical
-        from textual.widgets import Input, RichLog
+        from textual.containers import Vertical, VerticalScroll
+        from textual.widgets import Input
 
         app = _resolved_app(_args_new(), session_id="s-new12345", agent_id="mimir")
         async with app.run_test() as pilot:
             await pilot.pause()
             left = app.query_one("#left-column", Vertical)
-            transcript = app.query_one("#transcript", RichLog)
+            transcript = app.query_one("#transcript-scroll", VerticalScroll)
             prompt = app.query_one("#prompt", Input)
             assert transcript in left.walk_children()
             assert prompt in left.walk_children()
@@ -750,7 +814,7 @@ class TestLayoutShape:
             assert tools_tab is not None
 
     async def test_tools_log_inside_tools_tab(self) -> None:
-        """tools_log_inside_tools_tab: tools-log RichLog is a descendant of tools-tab TabPane."""
+        """tools_log_inside_tools_tab: tools-transcript RichLog is a descendant of tools-tab TabPane."""
         from textual.widgets import RichLog, TabPane
 
         app = _resolved_app(_args_new(), session_id="s-new12345", agent_id="mimir")
@@ -801,7 +865,7 @@ class TestLayoutShape:
             )
 
     async def test_debug_tab_exists(self) -> None:
-        """debug_tab_exists [v0.5.0]: right column has Debug TabPane + #debug-log RichLog."""
+        """debug_tab_exists [v0.5.0]: right column has Debug TabPane + #debug-transcript RichLog."""
         from textual.widgets import RichLog, TabPane
 
         app = _resolved_app(_args_new(), session_id="s-new12345", agent_id="mimir")
@@ -823,36 +887,45 @@ class TestLayoutShape:
             assert app.query_one("#side-panes", TabbedContent).active == "debug-tab"
 
     async def test_done_label_styled_success(self) -> None:
-        """done_label_styled_success [v0.5.1]: [done] label renders in Aurora green."""
+        """done_label_styled_success [v0.9.0]: [done] label mounts as Static
+        carrying a RichText with Aurora green style. Inspect the mounted
+        Static's `.content`.
+        """
         from rich.text import Text as RichText
+        from textual.containers import VerticalScroll
         from textual.widgets import RichLog
 
         app = _resolved_app(_args_new(), session_id="s-new12345", agent_id="mimir")
         async with app.run_test() as pilot:
             await pilot.pause()
-            # Probe the presenter directly — write a Done via state.render.
             from ratatoskr.tui import TuiPresenterState
-            log = app.query_one("#transcript", RichLog)
+            transcript = app.query_one("#transcript-scroll", VerticalScroll)
             state = TuiPresenterState()
-            seen: list = []
-            orig = log.write
-            log.write = lambda c, *a, **kw: (seen.append(c), orig(c, *a, **kw))[1]
+            mounted: list = []
+            orig_mount = transcript.mount
+
+            def spy_mount(*ch, **kw):
+                mounted.extend(ch)
+                return orig_mount(*ch, **kw)
+
+            transcript.mount = spy_mount  # type: ignore[method-assign]
             state.render(
                 _make_tui_done(),
-                log=log,
+                transcript=transcript,
                 tools_log=app.query_one("#tools-log", RichLog),
                 debug_log=app.query_one("#debug-log", RichLog),
                 thinking_log=MagicMock(),
                 raw=True,
             )
             done = next(
-                c for c in seen
-                if isinstance(c, RichText) and _text_of(c).startswith("[done]")
+                w.content for w in mounted
+                if isinstance(getattr(w, "content", None), RichText)
+                and _text_of(w.content).startswith("[done]")
             )
             assert done.style == "#16B866"  # Aurora green
 
     async def test_empty_state_placeholders_present(self) -> None:
-        """empty_state_placeholders_present [v0.5.1]: tools-log + debug-log show
+        """empty_state_placeholders_present [v0.5.1]: tools-transcript + debug-transcript show
         placeholder lines before any turn fires."""
         from textual.widgets import RichLog
 
@@ -1061,11 +1134,13 @@ async def _submit_and_wait(app: RatatoskrApp, pilot, content: str) -> None:
 class TestStreamTurnWorker:
     @respx.mock
     async def test_happy_text_done_no_double_print(self, monkeypatch: pytest.MonkeyPatch) -> None:
-        """happy_text_done_no_double_print [happy,tracer, v0.8.2]:
-        Text("hello") buffers; on Done, "hello" flushes as tail to transcript
-        + [done] label. v0.8.2 drops the post-Done Markdown body re-render
-        (was double-printing the response — streamed text + Markdown twice).
-        Only the turn-header Rule remains in the transcript.
+        """happy_text_done_no_double_print [happy,tracer, v0.9.0]:
+        Text("hello") mounts a Static(Markdown("hello")) into the transcript;
+        Done mounts a [done] label Static. The Markdown is rendered live (one
+        widget for the whole stream, updated in place), so there is NO
+        post-Done re-render — exactly ONE Markdown renderable lands in the
+        transcript for the response body. v0.9.0 supersedes v0.8.2's
+        drop-Markdown patch with proper live rendering.
         """
         stream = _sse_chunk("42:1", {"type": "text", "content": "hello"}) + _sse_chunk(
             "42:2", _DONE_BODY
@@ -1083,23 +1158,25 @@ class TestStreamTurnWorker:
             assert app.state == "idle"
             from rich.markdown import Markdown
 
-            # "hello" appears as a tail-flush; [done] label fires.
-            assert any(w == "hello" for w in writes)
-            assert any("[done]" in str(w) for w in writes)
-            # v0.8.2: NO Markdown body re-render (was the duplicate).
-            assert not any(isinstance(w, Markdown) for w in writes)
-            # The turn-header Rule is written to all 4 panes; we still expect
-            # SOME Rules in the spy (one per pane), but NOT the post-Done
-            # separator Rule that pre-v0.8.2 wrote.
-            # We rely on _spy_writes counting turn-header Rules only.
+            # The response body lives as ONE Markdown renderable mounted into
+            # the transcript; live updates happen via Static.update, not via
+            # re-mount, so there's exactly one Markdown in the spy stream.
+            markdowns = [w for w in writes if isinstance(w, Markdown)]
+            assert len(markdowns) == 1, (
+                f"v0.9.0: expected exactly ONE Markdown mounted, got {len(markdowns)}"
+            )
+            assert markdowns[0].markup == "hello"
+            # [done] label fires too.
+            assert any("[done]" in _text_of(w) for w in writes)
 
     @respx.mock
     async def test_raw_flag_skips_markdown_render(self, monkeypatch: pytest.MonkeyPatch) -> None:
-        """raw_flag_skips_markdown_render [trace, v0.6.0]:
-        With --raw, no Markdown render. A turn-header Rule IS still written
-        (v0.6.0 INV — turn correlation lives in every pane). The post-Done
-        Rule(separator) is suppressed; accumulated streamed text is written
-        as a plain string instead.
+        """raw_flag_skips_markdown_render [trace, v0.9.0]:
+        With --raw, the response widget holds plain str instead of Markdown.
+        Turn-header markers still appear in every pane: 3 RichLog panes
+        receive a Rule, the transcript-scroll receives a Static-wrapped
+        RichText (mounted, not written), giving 3 Rules in the captured
+        writes list.
         """
         stream = _sse_chunk("42:1", {"type": "text", "content": "hi"}) + _sse_chunk(
             "42:2", _DONE_BODY
@@ -1117,11 +1194,11 @@ class TestStreamTurnWorker:
 
             # No Markdown in raw mode.
             assert not any(isinstance(w, Markdown) for w in writes)
-            # Only turn-header Rules — one per pane (transcript + tools +
-            # debug + thinking = 4). No post-Done separator Rule.
+            # 3 Rules — one per RichLog pane (tools / debug / thinking).
+            # Transcript-scroll uses a Static turn-header Markdown alternative.
             rules = [w for w in writes if isinstance(w, Rule)]
-            assert len(rules) == 4, f"expected 4 turn-header Rules, got {len(rules)}"
-            # Accumulated text "hi" written as plain string post-Done.
+            assert len(rules) == 3, f"expected 3 turn-header Rules, got {len(rules)}"
+            # Accumulated text "hi" mounted as plain str into transcript.
             assert "hi" in writes
 
     @respx.mock
@@ -1495,8 +1572,14 @@ class TestActionInterrupt:
                 await pilot.pause(0.02)
             # Give _cancel_via_sse time to write the [cancel_failed] line
             await pilot.pause(0.05)
-            log = app.query_one("#transcript", RichLog)
-            rendered = "\n".join(str(strip.text) for strip in log.lines)
+            from textual.containers import VerticalScroll
+            from textual.widgets import Static
+            transcript = app.query_one("#transcript-scroll", VerticalScroll)
+            rendered = "\n".join(
+                str(child.content)
+                for child in transcript.children
+                if isinstance(child, Static)
+            )
             assert "[cancel_failed]" in rendered
             assert app.state == "cancelling"
             stream_gate.set()  # let stream finish for teardown

uv.lock

@@ -968,7 +968,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.8.2"
+version = "0.9.0"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },