From 46d9555daf098b906f9b6b30112795035bb900fe Mon Sep 17 00:00:00 2001
From: Daniel Nouri <daniel.nouri@gmail.com>
Date: Thu, 12 Feb 2026 22:20:49 +0100
Subject: [PATCH 1/3] test: add thinking whitespace normalization coverage

---
 test/pi-coding-agent-render-test.el | 105 ++++++++++++++++++++++++----
 1 file changed, 93 insertions(+), 12 deletions(-)

diff --git a/test/pi-coding-agent-render-test.el b/test/pi-coding-agent-render-test.el
index 8be3227..322fb92 100644
--- a/test/pi-coding-agent-render-test.el
+++ b/test/pi-coding-agent-render-test.el
@@ -147,6 +147,70 @@ Models may send \\n\\n before thinking content too."
     ;; Thinking start should appear directly after header, no blank line
     (should (string-match-p "Assistant\n=+\n>" (buffer-string)))))
 
+(ert-deftest pi-coding-agent-test-thinking-empty-lifecycle-no-visible-blockquote ()
+  "Empty thinking start/end should not leave a visible blank blockquote."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (pi-coding-agent--display-agent-start)
+    (pi-coding-agent--display-thinking-start)
+    (pi-coding-agent--display-thinking-end "")
+    (goto-char (point-min))
+    (should-not (re-search-forward "^>\\s-*$" nil t))))
+
+(ert-deftest pi-coding-agent-test-thinking-leading-trailing-newlines-normalized ()
+  "Thinking boundaries should not render extra empty blockquote lines."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (pi-coding-agent--display-agent-start)
+    (pi-coding-agent--display-thinking-start)
+    (pi-coding-agent--display-thinking-delta "\n\nSingle thought.\n\n")
+    (pi-coding-agent--display-thinking-end "")
+    (goto-char (point-min))
+    (should (re-search-forward "^> Single thought\\.$" nil t))
+    (goto-char (point-min))
+    (should-not (re-search-forward "^>\\s-*$" nil t))))
+
+(ert-deftest pi-coding-agent-test-thinking-paragraph-spacing-no-runaway-blank-lines ()
+  "Thinking paragraphs keep a single readable separator, not multiple blanks."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (pi-coding-agent--display-agent-start)
+    (pi-coding-agent--display-thinking-start)
+    (pi-coding-agent--display-thinking-delta
+     "First paragraph.\n\n\n\nSecond paragraph.")
+    (pi-coding-agent--display-thinking-end "")
+    (goto-char (point-min))
+    (should-not (re-search-forward "^>\\s-*$\n>\\s-*$" nil t))
+    (should (string-match-p "> First paragraph\\.\n>\\s-*\n> Second paragraph\\."
+                            (buffer-string)))))
+
+(ert-deftest pi-coding-agent-test-thinking-interleaved-with-tool-has-stable-spacing ()
+  "Interleaving thinking and tool events keeps one blank line separation."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (pi-coding-agent--handle-display-event '(:type "agent_start"))
+    (pi-coding-agent--handle-display-event
+     '(:type "message_start" :message (:role "assistant")))
+    (pi-coding-agent--handle-display-event
+     '(:type "message_update"
+       :assistantMessageEvent (:type "thinking_start")))
+    (pi-coding-agent--handle-display-event
+     '(:type "message_update"
+       :assistantMessageEvent (:type "toolcall_start" :contentIndex 0)
+       :message (:role "assistant"
+                 :content [(:type "toolCall" :id "call_1" :name "read"
+                            :arguments (:path "/tmp/AGENTS.md"))])))
+    (pi-coding-agent--handle-display-event
+     '(:type "message_update"
+       :assistantMessageEvent (:type "thinking_delta"
+                               :delta "Reviewing docs")))
+    (pi-coding-agent--handle-display-event
+     '(:type "message_update"
+       :assistantMessageEvent (:type "thinking_end" :content "")))
+    (let ((text (buffer-string)))
+      (should (string-match-p "Reviewing docs\n\nread /tmp/AGENTS\\.md" text))
+      (should-not (string-match-p "Reviewing docs\n\n\n" text)))))
+
 (ert-deftest pi-coding-agent-test-spacing-blank-line-before-tool ()
   "Tool block is preceded by blank line when after text."
   (with-temp-buffer
@@ -2848,53 +2912,70 @@ Commands with embedded newlines should not have any lines deleted."
     (should (search-forward "> Second line." nil t))))
 
 (ert-deftest pi-coding-agent-test-agent-end-clears-thinking-marker-buffer ()
-  "agent_end should detach thinking marker from the chat buffer."
+  "agent_end should detach thinking markers and clear thinking stream state."
   (with-temp-buffer
     (pi-coding-agent-chat-mode)
     (pi-coding-agent--display-agent-start)
     (pi-coding-agent--display-thinking-start)
-    (let ((marker pi-coding-agent--thinking-marker))
+    (let ((marker pi-coding-agent--thinking-marker)
+          (start-marker pi-coding-agent--thinking-start-marker))
+      (should (stringp pi-coding-agent--thinking-raw))
       (pi-coding-agent--display-agent-end)
       (should-not pi-coding-agent--thinking-marker)
-      (should-not (marker-buffer marker)))))
+      (should-not pi-coding-agent--thinking-start-marker)
+      (should-not pi-coding-agent--thinking-raw)
+      (should-not (marker-buffer marker))
+      (should-not (marker-buffer start-marker)))))
 
 (ert-deftest pi-coding-agent-test-message-start-clears-previous-thinking-marker ()
-  "message_start should detach leftover thinking marker from prior message."
+  "message_start should clear stale thinking markers and stream state."
   (with-temp-buffer
     (pi-coding-agent-chat-mode)
     (pi-coding-agent--display-agent-start)
     (pi-coding-agent--display-thinking-start)
-    (let ((marker pi-coding-agent--thinking-marker))
+    (let ((marker pi-coding-agent--thinking-marker)
+          (start-marker pi-coding-agent--thinking-start-marker))
       (pi-coding-agent--handle-display-event
        '(:type "message_start" :message (:role "assistant")))
       (should-not pi-coding-agent--thinking-marker)
-      (should-not (marker-buffer marker)))))
+      (should-not pi-coding-agent--thinking-start-marker)
+      (should-not pi-coding-agent--thinking-raw)
+      (should-not (marker-buffer marker))
+      (should-not (marker-buffer start-marker)))))
 
 (ert-deftest pi-coding-agent-test-message-start-user-clears-previous-thinking-marker ()
-  "message_start for user should also detach leftover thinking marker."
+  "message_start for user should also clear stale thinking state."
   (with-temp-buffer
     (pi-coding-agent-chat-mode)
     (pi-coding-agent--display-agent-start)
     (pi-coding-agent--display-thinking-start)
-    (let ((marker pi-coding-agent--thinking-marker))
+    (let ((marker pi-coding-agent--thinking-marker)
+          (start-marker pi-coding-agent--thinking-start-marker))
       (pi-coding-agent--handle-display-event
        '(:type "message_start"
          :message (:role "user" :content [(:type "text" :text "hi")])) )
       (should-not pi-coding-agent--thinking-marker)
-      (should-not (marker-buffer marker)))))
+      (should-not pi-coding-agent--thinking-start-marker)
+      (should-not pi-coding-agent--thinking-raw)
+      (should-not (marker-buffer marker))
+      (should-not (marker-buffer start-marker)))))
 
 (ert-deftest pi-coding-agent-test-message-start-custom-clears-previous-thinking-marker ()
-  "message_start for custom messages should clear stale thinking marker."
+  "message_start for custom messages should clear stale thinking state."
   (with-temp-buffer
     (pi-coding-agent-chat-mode)
     (pi-coding-agent--display-agent-start)
     (pi-coding-agent--display-thinking-start)
-    (let ((marker pi-coding-agent--thinking-marker))
+    (let ((marker pi-coding-agent--thinking-marker)
+          (start-marker pi-coding-agent--thinking-start-marker))
       (pi-coding-agent--handle-display-event
        '(:type "message_start"
          :message (:role "custom" :display t :content "done")))
       (should-not pi-coding-agent--thinking-marker)
-      (should-not (marker-buffer marker)))))
+      (should-not pi-coding-agent--thinking-start-marker)
+      (should-not pi-coding-agent--thinking-raw)
+      (should-not (marker-buffer marker))
+      (should-not (marker-buffer start-marker)))))
 
 (ert-deftest pi-coding-agent-test-blockquote-has-wrap-prefix ()
   "Blockquotes have wrap-prefix for continuation lines after font-lock."

From 83f07e8d18444e4ae29d1f8c7533b490e99dd3ef Mon Sep 17 00:00:00 2001
From: Daniel Nouri <daniel.nouri@gmail.com>
Date: Thu, 12 Feb 2026 22:21:02 +0100
Subject: [PATCH 2/3] fix: normalize thinking block whitespace while streaming

---
 pi-coding-agent-render.el | 106 ++++++++++++++++++++++++++++++++------
 pi-coding-agent-ui.el     |   8 +++
 2 files changed, 97 insertions(+), 17 deletions(-)

diff --git a/pi-coding-agent-render.el b/pi-coding-agent-render.el
index 1f72423..9f51e3d 100644
--- a/pi-coding-agent-render.el
+++ b/pi-coding-agent-render.el
@@ -193,11 +193,65 @@ tool headers do not move the thinking insertion point."
       (marker-position pi-coding-agent--thinking-marker)
     (marker-position pi-coding-agent--streaming-marker)))
 
+(defun pi-coding-agent--thinking-normalize-text (text)
+  "Normalize streaming thinking TEXT for stable markdown rendering.
+Removes boundary whitespace and collapses internal blank-line runs to
+at most one empty paragraph separator."
+  (let ((trimmed (string-trim (or text ""))))
+    (if (string-empty-p trimmed)
+        ""
+      (replace-regexp-in-string
+       "\n\\(?:[ \t]*\n\\)\\{2,\\}" "\n\n" trimmed))))
+
+(defun pi-coding-agent--thinking-blockquote-text (text)
+  "Convert normalized thinking TEXT to markdown blockquote lines."
+  (if (string-empty-p text)
+      ""
+    (concat "> " (replace-regexp-in-string "\n" "\n> " text))))
+
+(defun pi-coding-agent--render-thinking-content ()
+  "Render normalized accumulated thinking content in place.
+Returns non-nil when meaningful content remains after normalization."
+  (when (and (markerp pi-coding-agent--thinking-start-marker)
+             (markerp pi-coding-agent--thinking-marker)
+             (marker-position pi-coding-agent--thinking-start-marker)
+             (marker-position pi-coding-agent--thinking-marker))
+    (let* ((start (marker-position pi-coding-agent--thinking-start-marker))
+           (end (marker-position pi-coding-agent--thinking-marker))
+           (normalized (pi-coding-agent--thinking-normalize-text
+                        pi-coding-agent--thinking-raw))
+           (rendered (pi-coding-agent--thinking-blockquote-text normalized)))
+      (when (<= start end)
+        (goto-char start)
+        (delete-region start end)
+        (insert rendered)
+        (set-marker pi-coding-agent--thinking-marker (point)))
+      (not (string-empty-p normalized)))))
+
+(defun pi-coding-agent--ensure-thinking-separator ()
+  "Ensure exactly one blank line separator at point.
+Normalizes any existing newline run to two newlines."
+  (let ((start (point))
+        (scan (point))
+        (newline-count 0))
+    (while (eq (char-after scan) ?\n)
+      (setq newline-count (1+ newline-count))
+      (setq scan (1+ scan)))
+    (cond
+     ((< newline-count 2)
+      (insert (make-string (- 2 newline-count) ?\n)))
+     ((> newline-count 2)
+      (delete-region (+ start 2) (+ start newline-count))))))
+
 (defun pi-coding-agent--clear-thinking-marker ()
-  "Detach and clear `pi-coding-agent--thinking-marker'."
+  "Detach and clear thinking markers and raw streaming state."
   (when (markerp pi-coding-agent--thinking-marker)
     (set-marker pi-coding-agent--thinking-marker nil))
-  (setq pi-coding-agent--thinking-marker nil))
+  (when (markerp pi-coding-agent--thinking-start-marker)
+    (set-marker pi-coding-agent--thinking-start-marker nil))
+  (setq pi-coding-agent--thinking-marker nil
+        pi-coding-agent--thinking-start-marker nil
+        pi-coding-agent--thinking-raw nil))
 
 (defun pi-coding-agent--display-thinking-start ()
   "Insert opening marker for thinking block (blockquote)."
@@ -207,30 +261,43 @@ tool headers do not move the thinking insertion point."
       (pi-coding-agent--with-scroll-preservation
         (save-excursion
           (goto-char (marker-position pi-coding-agent--streaming-marker))
-          (insert "> ")
           ;; Track thinking insertion separately so it stays anchored even if
           ;; other block types (tool headers) interleave in the same message.
           ;; Keep insertion-type nil so inserts at this exact point happen
           ;; after the marker (we then advance it explicitly per delta).
           (pi-coding-agent--clear-thinking-marker)
-          (setq pi-coding-agent--thinking-marker (copy-marker (point) nil)))))))
+          (setq pi-coding-agent--thinking-raw "")
+          (let ((start (point)))
+            (insert "> ")
+            (setq pi-coding-agent--thinking-start-marker
+                  (copy-marker start nil))
+            (setq pi-coding-agent--thinking-marker
+                  (copy-marker (point) nil))))))))
 
 (defun pi-coding-agent--display-thinking-delta (delta)
   "Display streaming thinking DELTA in the current thinking block.
-Transforms newlines to include blockquote prefix.
+Normalizes boundary and paragraph whitespace while streaming.
 Inhibits modification hooks to prevent expensive jit-lock fontification
 on each delta - fontification happens at message end instead."
   (when (and delta pi-coding-agent--streaming-marker)
     (let ((inhibit-read-only t)
-          (inhibit-modification-hooks t)
-          ;; Transform newlines to include blockquote prefix on next line
-          (transformed (replace-regexp-in-string "\n" "\n> " delta)))
-      (pi-coding-agent--with-scroll-preservation
-        (save-excursion
-          (goto-char (pi-coding-agent--thinking-insert-position))
-          (insert transformed)
-          (when pi-coding-agent--thinking-marker
-            (set-marker pi-coding-agent--thinking-marker (point))))))))
+          (inhibit-modification-hooks t))
+      (if (and pi-coding-agent--thinking-start-marker
+               pi-coding-agent--thinking-marker)
+          (progn
+            (setq pi-coding-agent--thinking-raw
+                  (concat (or pi-coding-agent--thinking-raw "") delta))
+            (pi-coding-agent--with-scroll-preservation
+              (save-excursion
+                (pi-coding-agent--render-thinking-content))))
+        ;; Fallback for malformed event streams that skip thinking_start.
+        (let ((transformed (replace-regexp-in-string "\n" "\n> " delta)))
+          (pi-coding-agent--with-scroll-preservation
+            (save-excursion
+              (goto-char (pi-coding-agent--thinking-insert-position))
+              (insert transformed)
+              (when pi-coding-agent--thinking-marker
+                (set-marker pi-coding-agent--thinking-marker (point))))))))))
 
 (defun pi-coding-agent--display-thinking-end (_content)
   "End thinking block (blockquote).
@@ -240,9 +307,14 @@ CONTENT is ignored - we use what was already streamed."
     (let ((inhibit-read-only t))
       (pi-coding-agent--with-scroll-preservation
         (save-excursion
-          (goto-char (pi-coding-agent--thinking-insert-position))
-          ;; End blockquote with blank line
-          (insert "\n\n")
+          (if (and pi-coding-agent--thinking-start-marker
+                   pi-coding-agent--thinking-marker)
+              (when (pi-coding-agent--render-thinking-content)
+                (goto-char (pi-coding-agent--thinking-insert-position))
+                (pi-coding-agent--ensure-thinking-separator))
+            ;; Fallback for malformed event streams that skip thinking_start.
+            (goto-char (pi-coding-agent--thinking-insert-position))
+            (pi-coding-agent--ensure-thinking-separator))
           (pi-coding-agent--clear-thinking-marker))))))
 
 (defun pi-coding-agent--display-agent-end ()
diff --git a/pi-coding-agent-ui.el b/pi-coding-agent-ui.el
index 30099d6..bb72393 100644
--- a/pi-coding-agent-ui.el
+++ b/pi-coding-agent-ui.el
@@ -559,6 +559,14 @@ Unlike `pi-coding-agent--streaming-marker', this marker stays anchored
 in thinking text when other content blocks (for example, tool headers)
 interleave during streaming.")
 
+(defvar-local pi-coding-agent--thinking-start-marker nil
+  "Marker for the start of the current thinking block.
+Used to rewrite thinking content in place after whitespace normalization.")
+
+(defvar-local pi-coding-agent--thinking-raw nil
+  "Accumulated raw thinking deltas for the current thinking block.
+Normalized and re-rendered incrementally to avoid excess whitespace.")
+
 (defvar-local pi-coding-agent--line-parse-state 'line-start
   "Parsing state for current line during streaming.
 Values:

From 483f81d2e698458ded7395968aad1acc96edc209 Mon Sep 17 00:00:00 2001
From: Daniel Nouri <daniel.nouri@gmail.com>
Date: Thu, 12 Feb 2026 22:37:20 +0100
Subject: [PATCH 3/3] fix: harden thinking streaming normalization and state
 reset

---
 pi-coding-agent-menu.el             |  9 ++++
 pi-coding-agent-render.el           | 41 ++++++++++-------
 pi-coding-agent-ui.el               |  4 +-
 test/pi-coding-agent-menu-test.el   |  6 +++
 test/pi-coding-agent-render-test.el | 69 ++++++++++++++++-------------
 5 files changed, 79 insertions(+), 50 deletions(-)

diff --git a/pi-coding-agent-menu.el b/pi-coding-agent-menu.el
index 81e457d..ee91994 100644
--- a/pi-coding-agent-menu.el
+++ b/pi-coding-agent-menu.el
@@ -207,6 +207,12 @@ Prefers session name over first message when available."
 (defun pi-coding-agent--reset-session-state ()
   "Reset all session-specific state for a new session.
 Call this when starting a new session to ensure no stale state persists."
+  (dolist (marker (list pi-coding-agent--message-start-marker
+                        pi-coding-agent--streaming-marker
+                        pi-coding-agent--thinking-marker
+                        pi-coding-agent--thinking-start-marker))
+    (when (markerp marker)
+      (set-marker marker nil)))
   (setq pi-coding-agent--session-name nil
         pi-coding-agent--cached-stats nil
         pi-coding-agent--assistant-header-shown nil
@@ -214,6 +220,9 @@ Call this when starting a new session to ensure no stale state persists."
         pi-coding-agent--extension-status nil
         pi-coding-agent--in-code-block nil
         pi-coding-agent--in-thinking-block nil
+        pi-coding-agent--thinking-marker nil
+        pi-coding-agent--thinking-start-marker nil
+        pi-coding-agent--thinking-raw nil
         pi-coding-agent--line-parse-state 'line-start
         pi-coding-agent--pending-tool-overlay nil)
   ;; Use accessors for cross-module state
diff --git a/pi-coding-agent-render.el b/pi-coding-agent-render.el
index 9f51e3d..d222c71 100644
--- a/pi-coding-agent-render.el
+++ b/pi-coding-agent-render.el
@@ -195,13 +195,19 @@ tool headers do not move the thinking insertion point."
 
 (defun pi-coding-agent--thinking-normalize-text (text)
   "Normalize streaming thinking TEXT for stable markdown rendering.
-Removes boundary whitespace and collapses internal blank-line runs to
-at most one empty paragraph separator."
-  (let ((trimmed (string-trim (or text ""))))
-    (if (string-empty-p trimmed)
+Removes boundary blank lines and collapses internal blank-line runs to
+at most one empty paragraph separator while preserving indentation."
+  (let* ((source (or text ""))
+         (without-leading-blank-lines
+          (replace-regexp-in-string "\\`\\(?:[ \t]*\n\\)+" "" source))
+         (without-boundary-blank-lines
+          (replace-regexp-in-string "\\(?:\n[ \t]*\\)+\\'" ""
+                                    without-leading-blank-lines)))
+    (if (string-empty-p without-boundary-blank-lines)
         ""
       (replace-regexp-in-string
-       "\n\\(?:[ \t]*\n\\)\\{2,\\}" "\n\n" trimmed))))
+       "\n\\(?:[ \t]*\n\\)\\{2,\\}" "\n\n"
+       without-boundary-blank-lines))))
 
 (defun pi-coding-agent--thinking-blockquote-text (text)
   "Convert normalized thinking TEXT to markdown blockquote lines."
@@ -222,11 +228,14 @@ Returns non-nil when meaningful content remains after normalization."
                         pi-coding-agent--thinking-raw))
            (rendered (pi-coding-agent--thinking-blockquote-text normalized)))
       (when (<= start end)
-        (goto-char start)
-        (delete-region start end)
-        (insert rendered)
-        (set-marker pi-coding-agent--thinking-marker (point)))
-      (not (string-empty-p normalized)))))
+        (let ((existing (buffer-substring-no-properties start end)))
+          (unless (equal existing rendered)
+            (goto-char start)
+            (delete-region start end)
+            (insert rendered)
+            (set-marker pi-coding-agent--thinking-marker (point)))))
+      (and (<= start end)
+           (not (string-empty-p normalized))))))
 
 (defun pi-coding-agent--ensure-thinking-separator ()
   "Ensure exactly one blank line separator at point.
@@ -243,8 +252,8 @@ Normalizes any existing newline run to two newlines."
      ((> newline-count 2)
       (delete-region (+ start 2) (+ start newline-count))))))
 
-(defun pi-coding-agent--clear-thinking-marker ()
-  "Detach and clear thinking markers and raw streaming state."
+(defun pi-coding-agent--reset-thinking-state ()
+  "Detach and clear all thinking-stream state for the current turn."
   (when (markerp pi-coding-agent--thinking-marker)
     (set-marker pi-coding-agent--thinking-marker nil))
   (when (markerp pi-coding-agent--thinking-start-marker)
@@ -265,7 +274,7 @@ Normalizes any existing newline run to two newlines."
           ;; other block types (tool headers) interleave in the same message.
           ;; Keep insertion-type nil so inserts at this exact point happen
           ;; after the marker (we then advance it explicitly per delta).
-          (pi-coding-agent--clear-thinking-marker)
+          (pi-coding-agent--reset-thinking-state)
           (setq pi-coding-agent--thinking-raw "")
           (let ((start (point)))
             (insert "> ")
@@ -315,7 +324,7 @@ CONTENT is ignored - we use what was already streamed."
             ;; Fallback for malformed event streams that skip thinking_start.
             (goto-char (pi-coding-agent--thinking-insert-position))
             (pi-coding-agent--ensure-thinking-separator))
-          (pi-coding-agent--clear-thinking-marker))))))
+          (pi-coding-agent--reset-thinking-state))))))
 
 (defun pi-coding-agent--display-agent-end ()
   "Finalize agent turn: normalize whitespace, handle abort, process queue.
@@ -324,7 +333,7 @@ Note: status is set to `idle' by the event handler."
   (setq pi-coding-agent--local-user-message nil)
   (setq pi-coding-agent--streaming-tool-id nil)
   (setq pi-coding-agent--in-thinking-block nil)
-  (pi-coding-agent--clear-thinking-marker)
+  (pi-coding-agent--reset-thinking-state)
   (let ((was-aborted pi-coding-agent--aborted))
     (let ((inhibit-read-only t))
       (pi-coding-agent--tool-overlay-finalize 'pi-coding-agent-tool-block-error)
@@ -622,7 +631,7 @@ Updates buffer-local state and renders display updates."
             (role (plist-get message :role)))
        ;; A new message starts a fresh rendering context.
        (setq pi-coding-agent--in-thinking-block nil)
-       (pi-coding-agent--clear-thinking-marker)
+       (pi-coding-agent--reset-thinking-state)
        (pcase role
          ("user"
           ;; User message from pi - check if we displayed it locally
diff --git a/pi-coding-agent-ui.el b/pi-coding-agent-ui.el
index bb72393..ddc19de 100644
--- a/pi-coding-agent-ui.el
+++ b/pi-coding-agent-ui.el
@@ -550,8 +550,8 @@ TYPE is :chat or :input.  Returns the buffer."
 Used to suppress ATX heading transforms inside code.")
 
 (defvar-local pi-coding-agent--in-thinking-block nil
-  "Non-nil when streaming inside a thinking block.
-Used to add blockquote prefix to each line.")
+  "Non-nil while processing a thinking block for the current message.
+Used for lifecycle resets when new messages or turns begin.")
 
 (defvar-local pi-coding-agent--thinking-marker nil
   "Marker for insertion point inside the current thinking block.
diff --git a/test/pi-coding-agent-menu-test.el b/test/pi-coding-agent-menu-test.el
index a992f51..9169f7c 100644
--- a/test/pi-coding-agent-menu-test.el
+++ b/test/pi-coding-agent-menu-test.el
@@ -71,6 +71,9 @@
           pi-coding-agent--extension-status '(("ext1" . "status"))
           pi-coding-agent--message-start-marker (point-marker)
           pi-coding-agent--streaming-marker (point-marker)
+          pi-coding-agent--thinking-marker (point-marker)
+          pi-coding-agent--thinking-start-marker (point-marker)
+          pi-coding-agent--thinking-raw "pending"
           pi-coding-agent--in-code-block t
           pi-coding-agent--in-thinking-block t
           pi-coding-agent--line-parse-state 'code-fence
@@ -90,6 +93,9 @@
     (should (null pi-coding-agent--extension-status))
     (should (null pi-coding-agent--message-start-marker))
     (should (null pi-coding-agent--streaming-marker))
+    (should (null pi-coding-agent--thinking-marker))
+    (should (null pi-coding-agent--thinking-start-marker))
+    (should (null pi-coding-agent--thinking-raw))
     (should (null pi-coding-agent--in-code-block))
     (should (null pi-coding-agent--in-thinking-block))
     (should (eq pi-coding-agent--line-parse-state 'line-start))
diff --git a/test/pi-coding-agent-render-test.el b/test/pi-coding-agent-render-test.el
index 322fb92..eb525d1 100644
--- a/test/pi-coding-agent-render-test.el
+++ b/test/pi-coding-agent-render-test.el
@@ -170,6 +170,29 @@ Models may send \\n\\n before thinking content too."
     (goto-char (point-min))
     (should-not (re-search-forward "^>\\s-*$" nil t))))
 
+(ert-deftest pi-coding-agent-test-thinking-normalization-preserves-first-line-indentation ()
+  "Normalization should trim blank boundaries without stripping indentation."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (pi-coding-agent--display-agent-start)
+    (pi-coding-agent--display-thinking-start)
+    (pi-coding-agent--display-thinking-delta "\n\n  indented thought")
+    (pi-coding-agent--display-thinking-end "")
+    (should (string-match-p "^>   indented thought" (buffer-string)))))
+
+(ert-deftest pi-coding-agent-test-thinking-whitespace-only-delta-does-not-rewrite-buffer ()
+  "Adding ignorable trailing whitespace should not rewrite rendered thinking."
+  (with-temp-buffer
+    (pi-coding-agent-chat-mode)
+    (pi-coding-agent--display-agent-start)
+    (pi-coding-agent--display-thinking-start)
+    (pi-coding-agent--display-thinking-delta "Stable")
+    (let ((before (buffer-string))
+          (before-tick (buffer-chars-modified-tick)))
+      (pi-coding-agent--display-thinking-delta "\n")
+      (should (equal before (buffer-string)))
+      (should (= before-tick (buffer-chars-modified-tick))))))
+
 (ert-deftest pi-coding-agent-test-thinking-paragraph-spacing-no-runaway-blank-lines ()
   "Thinking paragraphs keep a single readable separator, not multiple blanks."
   (with-temp-buffer
@@ -2927,55 +2950,37 @@ Commands with embedded newlines should not have any lines deleted."
       (should-not (marker-buffer marker))
       (should-not (marker-buffer start-marker)))))
 
-(ert-deftest pi-coding-agent-test-message-start-clears-previous-thinking-marker ()
-  "message_start should clear stale thinking markers and stream state."
+(defun pi-coding-agent-test--assert-message-start-clears-thinking-state (event)
+  "Assert that message_start EVENT clears all thinking-stream state."
   (with-temp-buffer
     (pi-coding-agent-chat-mode)
     (pi-coding-agent--display-agent-start)
     (pi-coding-agent--display-thinking-start)
     (let ((marker pi-coding-agent--thinking-marker)
           (start-marker pi-coding-agent--thinking-start-marker))
-      (pi-coding-agent--handle-display-event
-       '(:type "message_start" :message (:role "assistant")))
+      (pi-coding-agent--handle-display-event event)
       (should-not pi-coding-agent--thinking-marker)
       (should-not pi-coding-agent--thinking-start-marker)
       (should-not pi-coding-agent--thinking-raw)
       (should-not (marker-buffer marker))
       (should-not (marker-buffer start-marker)))))
 
+(ert-deftest pi-coding-agent-test-message-start-clears-previous-thinking-marker ()
+  "message_start should clear stale thinking markers and stream state."
+  (pi-coding-agent-test--assert-message-start-clears-thinking-state
+   '(:type "message_start" :message (:role "assistant"))))
+
 (ert-deftest pi-coding-agent-test-message-start-user-clears-previous-thinking-marker ()
   "message_start for user should also clear stale thinking state."
-  (with-temp-buffer
-    (pi-coding-agent-chat-mode)
-    (pi-coding-agent--display-agent-start)
-    (pi-coding-agent--display-thinking-start)
-    (let ((marker pi-coding-agent--thinking-marker)
-          (start-marker pi-coding-agent--thinking-start-marker))
-      (pi-coding-agent--handle-display-event
-       '(:type "message_start"
-         :message (:role "user" :content [(:type "text" :text "hi")])) )
-      (should-not pi-coding-agent--thinking-marker)
-      (should-not pi-coding-agent--thinking-start-marker)
-      (should-not pi-coding-agent--thinking-raw)
-      (should-not (marker-buffer marker))
-      (should-not (marker-buffer start-marker)))))
+  (pi-coding-agent-test--assert-message-start-clears-thinking-state
+   '(:type "message_start"
+     :message (:role "user" :content [(:type "text" :text "hi")]))))
 
 (ert-deftest pi-coding-agent-test-message-start-custom-clears-previous-thinking-marker ()
   "message_start for custom messages should clear stale thinking state."
-  (with-temp-buffer
-    (pi-coding-agent-chat-mode)
-    (pi-coding-agent--display-agent-start)
-    (pi-coding-agent--display-thinking-start)
-    (let ((marker pi-coding-agent--thinking-marker)
-          (start-marker pi-coding-agent--thinking-start-marker))
-      (pi-coding-agent--handle-display-event
-       '(:type "message_start"
-         :message (:role "custom" :display t :content "done")))
-      (should-not pi-coding-agent--thinking-marker)
-      (should-not pi-coding-agent--thinking-start-marker)
-      (should-not pi-coding-agent--thinking-raw)
-      (should-not (marker-buffer marker))
-      (should-not (marker-buffer start-marker)))))
+  (pi-coding-agent-test--assert-message-start-clears-thinking-state
+   '(:type "message_start"
+     :message (:role "custom" :display t :content "done"))))
 
 (ert-deftest pi-coding-agent-test-blockquote-has-wrap-prefix ()
   "Blockquotes have wrap-prefix for continuation lines after font-lock."