diff --git a/README.md b/README.md
index 88f0def..07d95b1 100644
--- a/README.md
+++ b/README.md
@@ -50,12 +50,13 @@ npm run build
 
 The build runs type-aware linting, scheduler regression tests, TypeScript checking, and the Rollup bundle. Test plugin builds in a dedicated Obsidian vault before using them with personal notes.
 
-## 1.6.0
+## 1.8.0
 
-- Fix external source audits that omit development-only type packages.
-- Prevent rapid retry loops after failed periodic sync attempts.
-- Correct project-heading precedence when project grouping is enabled.
-- Add type-aware linting and scheduler regression tests to the build.
+- Prevent repeated Things log sections in daily notes after changing the configured Section heading.
+- Mark newly synced Things log sections so future syncs can replace them even if the visible heading changes again.
+- Consolidate legacy duplicate generated Things sections on resync when they contain the same Things task IDs.
+- Keep review-calendar task counts working after generated section heading changes.
+- Keep the settings tab compatible with public Obsidian 1.12.x while deferring the 1.13-only `getSettingDefinitions()` API.
 
 ## 1.7.0
 
@@ -64,6 +65,13 @@ The build runs type-aware linting, scheduler regression tests, TypeScript checki
 - Keep Obsidian and Papa Parse declarations available to external source audits through registry-resolvable production dependencies.
 - Restore strict unsafe-value linting and add frontmatter parsing regression tests.
 
+## 1.6.0
+
+- Fix external source audits that omit development-only type packages.
+- Prevent rapid retry loops after failed periodic sync attempts.
+- Correct project-heading precedence when project grouping is enabled.
+- Add type-aware linting and scheduler regression tests to the build.
+
 ## Publishing
 
 For an Obsidian community plugin release, each GitHub release must include:
@@ -74,6 +82,7 @@ For an Obsidian community plugin release, each GitHub release must include:
 
 The release tag must match the `version` in `manifest.json`.
 Attach these files directly to the release; do not attach `versions.json` or a zip file.
+Release descriptions are read from `RELEASE_NOTES.md`.
 
 For a new release:
 
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
new file mode 100644
index 0000000..409ba77
--- /dev/null
+++ b/RELEASE_NOTES.md
@@ -0,0 +1,7 @@
+# Things Toolkit 1.8.0
+
+- Prevent repeated Things log sections in daily notes after changing the configured Section heading.
+- Mark newly synced Things log sections so future syncs can replace them even if the visible heading changes again.
+- Consolidate legacy duplicate generated Things sections on resync when they contain the same Things task IDs.
+- Keep review-calendar task counts working after generated section heading changes.
+- Keep the settings tab compatible with public Obsidian 1.12.x while deferring the 1.13-only `getSettingDefinitions()` API.
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 69dbb02..5b586f6 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -32,8 +32,8 @@ export default tseslint.config(
       "@typescript-eslint/no-explicit-any": "warn",
 
       /*
-       * PluginSettingTab.display() is required for the declared Obsidian 1.12
-       * minimum; the replacement settings API was introduced in 1.13.
+       * PluginSettingTab.display() is still required for public Obsidian 1.12.x.
+       * getSettingDefinitions() is available in 1.13, which is not public yet.
        */
       "@typescript-eslint/no-deprecated": "off",
       "obsidianmd/ui/sentence-case": [
diff --git a/manifest.json b/manifest.json
index c88a6fc..d39dcab 100644
--- a/manifest.json
+++ b/manifest.json
@@ -2,9 +2,9 @@
   "id": "things-toolkit",
   "name": "Things Toolkit",
   "description": "Sync Things3 completions into daily notes with review stats and privacy-aware macOS access.",
-  "version": "1.7.1",
+  "version": "1.8.0",
   "author": "yangcht",
   "authorUrl": "https://github.com/yangcht",
   "isDesktopOnly": false,
   "minAppVersion": "1.12.0"
-}
\ No newline at end of file
+}
diff --git a/package-lock.json b/package-lock.json
index 18028a4..07166c1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "obsidian-things-toolkit-plugin",
-  "version": "1.7.1",
+  "version": "1.8.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "obsidian-things-toolkit-plugin",
-      "version": "1.7.1",
+      "version": "1.8.0",
       "license": "MIT",
       "dependencies": {
         "@types/papaparse": "5.3.1",
diff --git a/package.json b/package.json
index 0fe7cc5..68228ae 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "obsidian-things-toolkit-plugin",
-  "version": "1.7.1",
+  "version": "1.8.0",
   "type": "module",
   "description": "Sync Things3 completions into Obsidian daily notes with review stats",
   "author": "yangcht",
@@ -13,8 +13,8 @@
     "test:typecheck": "tsc --noEmit -p tsconfig.test.json",
     "build": "npm run lint && npm test && npm run typecheck && npm run test:typecheck && rollup -c",
     "build:nolint": "rollup -c",
-    "release:create": "npm run build && VERSION=$(node -p \"require('./manifest.json').version\") && gh release create \"$VERSION\" main.js manifest.json styles.css --title \"$VERSION\" --notes \"Release $VERSION\"",
-    "release:upload": "npm run build && VERSION=$(node -p \"require('./manifest.json').version\") && (gh release delete-asset \"$VERSION\" versions.json -y >/dev/null 2>&1 || true) && gh release upload \"$VERSION\" main.js manifest.json styles.css --clobber",
+    "release:create": "npm run build && VERSION=$(node -p \"require('./manifest.json').version\") && gh release create \"$VERSION\" main.js manifest.json styles.css --title \"$VERSION\" --notes-file RELEASE_NOTES.md",
+    "release:upload": "npm run build && VERSION=$(node -p \"require('./manifest.json').version\") && gh release edit \"$VERSION\" --notes-file RELEASE_NOTES.md && (gh release delete-asset \"$VERSION\" versions.json -y >/dev/null 2>&1 || true) && gh release upload \"$VERSION\" main.js manifest.json styles.css --clobber",
     "test:watch": "npm test -- --watch"
   },
   "dependencies": {
diff --git a/src/index.ts b/src/index.ts
index 6782426..0a44c85 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -41,7 +41,6 @@ import {
 import {
   countThingsTasksInSection,
   groupBy,
-  isMacOS,
   updateSection,
 } from "./textUtils";
 
@@ -153,7 +152,7 @@ export default class ThingsToolkitPlugin extends Plugin {
   }
 
   isSyncSupported(): boolean {
-    return Platform.isDesktopApp && isMacOS();
+    return Platform.isDesktopApp && Platform.isMacOS;
   }
 
   getSelectedReviewDate(): string {
diff --git a/src/logbookSection.ts b/src/logbookSection.ts
new file mode 100644
index 0000000..404bd3b
--- /dev/null
+++ b/src/logbookSection.ts
@@ -0,0 +1,404 @@
+export function getHeadingLevel(line = ""): number | null {
+  const heading = line.match(/^(#{1,6})\s+\S/);
+  return heading ? heading[1].length : null;
+}
+
+export const LOGBOOK_SECTION_START_MARKER =
+  "<!-- things-toolkit-logbook:start -->";
+export const LOGBOOK_SECTION_END_MARKER =
+  "<!-- things-toolkit-logbook:end -->";
+
+const THINGS_TASK_LINE_REGEX =
+  /^- \[[ xXcC]\] .*things:\/\/\/show\?id=([^\s)]+)/;
+
+export interface SectionRange {
+  startLine: number;
+  endLine: number;
+  taskIds: Set<string>;
+}
+
+export interface SectionContentUpdate {
+  contents: string;
+  didChange: boolean;
+}
+
+export interface LogbookSectionUpdate extends SectionContentUpdate {
+  managedSection: string;
+  rangesToUpdate: SectionRange[];
+  replacementRange: SectionRange | null;
+}
+
+export function updateSectionContents(
+  fileContents: string,
+  heading: string,
+  sectionContents: string
+): SectionContentUpdate {
+  const update = buildLogbookSectionUpdate(
+    fileContents,
+    heading,
+    sectionContents
+  );
+
+  return {
+    contents: update.contents,
+    didChange: update.didChange,
+  };
+}
+
+export function buildLogbookSectionUpdate(
+  fileContents: string,
+  heading: string,
+  sectionContents: string
+): LogbookSectionUpdate {
+  const headingLine = getLogbookHeadingLine(heading);
+  if (!getHeadingLevel(headingLine)) {
+    throw new Error(`Invalid logbook section heading: ${heading}`);
+  }
+
+  const managedSection = toManagedLogbookSection(sectionContents);
+  const fileLines = fileContents.split("\n");
+  const renderedTaskIds = extractThingsTaskIds(sectionContents.split("\n"));
+  const markedRanges = findMarkedLogbookSectionRanges(fileLines);
+  const exactHeadingRanges = findHeadingSectionRanges(fileLines, headingLine);
+  const legacyRanges = findGeneratedLogbookSectionRanges(fileLines).filter(
+    (range) => hasSharedTaskId(range.taskIds, renderedTaskIds)
+  );
+  const targetRange =
+    markedRanges[0] || exactHeadingRanges[0] || legacyRanges[0];
+
+  if (!targetRange) {
+    const nextContents = appendLogbookSection(fileContents, managedSection);
+    return {
+      contents: nextContents,
+      didChange: nextContents !== fileContents,
+      managedSection,
+      rangesToUpdate: [],
+      replacementRange: null,
+    };
+  }
+
+  const rangesToUpdate = normalizeSectionRanges([
+    ...markedRanges,
+    ...exactHeadingRanges,
+    ...legacyRanges,
+  ]);
+  const replacementRange =
+    rangesToUpdate.find((range) => isSameRange(range, targetRange)) ||
+    rangesToUpdate[0];
+  const nextContents = replaceSectionRanges(
+    fileLines,
+    rangesToUpdate,
+    replacementRange,
+    managedSection
+  );
+
+  return {
+    contents: nextContents,
+    didChange: nextContents !== fileContents,
+    managedSection,
+    rangesToUpdate,
+    replacementRange,
+  };
+}
+
+export function getSectionContents(
+  fileContents: string,
+  heading: string
+): string {
+  const headingLine = getLogbookHeadingLine(heading);
+  if (!getHeadingLevel(headingLine)) {
+    return "";
+  }
+
+  const fileLines = fileContents.split("\n");
+  const markedRange = findMarkedLogbookSectionRanges(fileLines)[0];
+  const exactRange = findHeadingSectionRanges(fileLines, headingLine)[0];
+  const legacyRange = findGeneratedLogbookSectionRanges(fileLines)[0];
+  const sectionRange = markedRange || exactRange || legacyRange;
+
+  return sectionRange ? getSectionRangeContents(fileLines, sectionRange) : "";
+}
+
+export function countThingsTasksInSection(
+  fileContents: string,
+  heading: string
+): number {
+  const sectionContents = getSectionContents(fileContents, heading);
+  if (!sectionContents) {
+    return 0;
+  }
+
+  return extractThingsTaskIds(sectionContents.split("\n")).size;
+}
+
+export function getAppendText(
+  fileContents: string,
+  managedSection: string
+): string {
+  if (!fileContents) {
+    return managedSection;
+  }
+
+  const separator = fileContents.endsWith("\n\n")
+    ? ""
+    : fileContents.endsWith("\n")
+      ? "\n"
+      : "\n\n";
+  return `${separator}${managedSection}`;
+}
+
+export function isSameRange(left: SectionRange, right: SectionRange): boolean {
+  return left.startLine === right.startLine && left.endLine === right.endLine;
+}
+
+function getLogbookHeadingLine(heading: string): string {
+  return (
+    heading
+      .split("\n")
+      .map((line) => line.trim())
+      .find((line) => getHeadingLevel(line) !== null) || heading.trim()
+  );
+}
+
+function toManagedLogbookSection(sectionContents: string): string {
+  const trimmedSectionContents = sectionContents.trimEnd();
+  if (
+    trimmedSectionContents.startsWith(LOGBOOK_SECTION_START_MARKER) &&
+    trimmedSectionContents.endsWith(LOGBOOK_SECTION_END_MARKER)
+  ) {
+    return trimmedSectionContents;
+  }
+
+  return [
+    LOGBOOK_SECTION_START_MARKER,
+    trimmedSectionContents,
+    LOGBOOK_SECTION_END_MARKER,
+  ].join("\n");
+}
+
+function appendLogbookSection(
+  fileContents: string,
+  managedSection: string
+): string {
+  return `${fileContents}${getAppendText(fileContents, managedSection)}`;
+}
+
+function findMarkedLogbookSectionRanges(fileLines: string[]): SectionRange[] {
+  const ranges: SectionRange[] = [];
+
+  for (let i = 0; i < fileLines.length; i++) {
+    if (fileLines[i].trim() !== LOGBOOK_SECTION_START_MARKER) {
+      continue;
+    }
+
+    const endMarkerLine = fileLines.findIndex(
+      (line, index) =>
+        index > i && line.trim() === LOGBOOK_SECTION_END_MARKER
+    );
+
+    if (endMarkerLine === -1) {
+      continue;
+    }
+
+    ranges.push(createSectionRange(fileLines, i, endMarkerLine + 1));
+    i = endMarkerLine;
+  }
+
+  return ranges;
+}
+
+function findHeadingSectionRanges(
+  fileLines: string[],
+  headingLine: string
+): SectionRange[] {
+  const ranges: SectionRange[] = [];
+
+  for (let i = 0; i < fileLines.length; i++) {
+    if (fileLines[i].trim() !== headingLine) {
+      continue;
+    }
+
+    const headingLevel = getHeadingLevel(fileLines[i]);
+    if (!headingLevel) {
+      continue;
+    }
+
+    ranges.push(
+      createSectionRange(
+        fileLines,
+        i,
+        findSectionEndLine(fileLines, i, headingLevel)
+      )
+    );
+  }
+
+  return ranges;
+}
+
+function findGeneratedLogbookSectionRanges(fileLines: string[]): SectionRange[] {
+  const ranges: SectionRange[] = [];
+
+  for (let i = 0; i < fileLines.length; i++) {
+    const headingLevel = getHeadingLevel(fileLines[i]);
+    if (!headingLevel) {
+      continue;
+    }
+
+    const endLine = findSectionEndLine(fileLines, i, headingLevel);
+    const sectionLines = fileLines.slice(i, endLine);
+    if (isGeneratedLogbookSection(sectionLines, headingLevel)) {
+      ranges.push(createSectionRange(fileLines, i, endLine));
+    }
+  }
+
+  return removeContainedRanges(ranges);
+}
+
+function findSectionEndLine(
+  fileLines: string[],
+  startLine: number,
+  headingLevel: number
+): number {
+  for (let i = startLine + 1; i < fileLines.length; i++) {
+    const currentHeadingLevel = getHeadingLevel(fileLines[i]);
+    if (currentHeadingLevel && currentHeadingLevel <= headingLevel) {
+      return i;
+    }
+  }
+
+  return fileLines.length;
+}
+
+function createSectionRange(
+  fileLines: string[],
+  startLine: number,
+  endLine: number
+): SectionRange {
+  return {
+    startLine,
+    endLine,
+    taskIds: extractThingsTaskIds(fileLines.slice(startLine, endLine)),
+  };
+}
+
+function isGeneratedLogbookSection(
+  sectionLines: string[],
+  headingLevel: number
+): boolean {
+  const taskIds = extractThingsTaskIds(sectionLines);
+  if (taskIds.size === 0) {
+    return false;
+  }
+
+  return sectionLines.slice(1).every((line) => {
+    if (!line.trim()) {
+      return true;
+    }
+
+    const currentHeadingLevel = getHeadingLevel(line);
+    if (currentHeadingLevel) {
+      return currentHeadingLevel > headingLevel;
+    }
+
+    return THINGS_TASK_LINE_REGEX.test(line) || isIndentedLine(line);
+  });
+}
+
+function isIndentedLine(line: string): boolean {
+  return line.startsWith("\t") || line.startsWith(" ");
+}
+
+function extractThingsTaskIds(lines: string[]): Set<string> {
+  const taskIds = new Set<string>();
+
+  lines.forEach((line) => {
+    const taskMatch = line.match(THINGS_TASK_LINE_REGEX);
+    if (taskMatch?.[1]) {
+      taskIds.add(taskMatch[1]);
+    }
+  });
+
+  return taskIds;
+}
+
+function hasSharedTaskId(left: Set<string>, right: Set<string>): boolean {
+  if (left.size === 0 || right.size === 0) {
+    return false;
+  }
+
+  for (const taskId of left) {
+    if (right.has(taskId)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+function normalizeSectionRanges(ranges: SectionRange[]): SectionRange[] {
+  return [...ranges]
+    .sort(
+      (left, right) =>
+        left.startLine - right.startLine || right.endLine - left.endLine
+    )
+    .reduce<SectionRange[]>((acc, range) => {
+      const previousRange = acc[acc.length - 1];
+      if (!previousRange || range.startLine >= previousRange.endLine) {
+        acc.push(range);
+        return acc;
+      }
+
+      if (range.endLine > previousRange.endLine) {
+        previousRange.endLine = range.endLine;
+      }
+
+      return acc;
+    }, []);
+}
+
+function removeContainedRanges(ranges: SectionRange[]): SectionRange[] {
+  return ranges.filter(
+    (range) =>
+      !ranges.some(
+        (otherRange) =>
+          otherRange.startLine < range.startLine &&
+          range.endLine <= otherRange.endLine
+      )
+  );
+}
+
+function replaceSectionRanges(
+  fileLines: string[],
+  ranges: SectionRange[],
+  replacementRange: SectionRange,
+  managedSection: string
+): string {
+  const nextLines: string[] = [];
+  let cursor = 0;
+
+  ranges.forEach((range) => {
+    nextLines.push(...fileLines.slice(cursor, range.startLine));
+
+    if (isSameRange(range, replacementRange)) {
+      nextLines.push(...managedSection.split("\n"));
+    }
+
+    cursor = range.endLine;
+  });
+
+  nextLines.push(...fileLines.slice(cursor));
+  return nextLines.join("\n");
+}
+
+function getSectionRangeContents(
+  fileLines: string[],
+  range: SectionRange
+): string {
+  const isMarkedRange =
+    fileLines[range.startLine]?.trim() === LOGBOOK_SECTION_START_MARKER &&
+    fileLines[range.endLine - 1]?.trim() === LOGBOOK_SECTION_END_MARKER;
+  const startLine = isMarkedRange ? range.startLine + 1 : range.startLine;
+  const endLine = isMarkedRange ? range.endLine - 1 : range.endLine;
+
+  return fileLines.slice(startLine, endLine).join("\n");
+}
diff --git a/src/textUtils.ts b/src/textUtils.ts
index bfb0c83..7e87411 100644
--- a/src/textUtils.ts
+++ b/src/textUtils.ts
@@ -1,12 +1,18 @@
-import { Platform } from "obsidian";
 import type { App, TFile } from "obsidian";
 
 import { getEditorForFile } from "./fileUtils";
+import {
+  buildLogbookSectionUpdate,
+  getAppendText,
+  isSameRange,
+  type SectionRange,
+} from "./logbookSection";
 
-export function getHeadingLevel(line = ""): number | null {
-  const heading = line.match(/^(#{1,6})\s+\S/);
-  return heading ? heading[1].length : null;
-}
+export {
+  countThingsTasksInSection,
+  getHeadingLevel,
+  updateSectionContents,
+} from "./logbookSection";
 
 export function toHeading(
   title: string,
@@ -37,139 +43,78 @@ export function groupBy<T>(
   }, {} as Record<string | number, T[]>);
 }
 
-export function isMacOS(): boolean {
-  return Platform.isMacOS;
-}
-
 export async function updateSection(
   app: App,
   file: TFile,
   heading: string,
   sectionContents: string
 ): Promise<boolean> {
-  const headingLevel = getHeadingLevel(heading);
-  if (!headingLevel) {
-    throw new Error(`Invalid logbook section heading: ${heading}`);
-  }
-
   const { vault } = app;
   const fileContents = await vault.read(file);
-  const fileLines = fileContents.split("\n");
+  const update = buildLogbookSectionUpdate(
+    fileContents,
+    heading,
+    sectionContents
+  );
 
-  let logbookSectionLineNum = -1;
-  let nextSectionLineNum = -1;
-
-  for (let i = 0; i < fileLines.length; i++) {
-    if (fileLines[i].trim() === heading) {
-      logbookSectionLineNum = i;
-    } else if (logbookSectionLineNum !== -1) {
-      const currLevel = getHeadingLevel(fileLines[i]);
-      if (currLevel && currLevel <= headingLevel) {
-        nextSectionLineNum = i;
-        break;
-      }
-    }
+  if (!update.didChange) {
+    return false;
   }
 
   const editor = getEditorForFile(app, file);
   if (editor) {
-    if (logbookSectionLineNum !== -1) {
-      const currentSection = fileLines
-        .slice(
-          logbookSectionLineNum,
-          nextSectionLineNum !== -1 ? nextSectionLineNum : fileLines.length
-        )
-        .join("\n")
-        .trimEnd();
-
-      if (currentSection === sectionContents.trimEnd()) {
-        return false;
-      }
-
-      const from = { line: logbookSectionLineNum, ch: 0 };
-      const to =
-        nextSectionLineNum !== -1
-          ? { line: nextSectionLineNum, ch: 0 }
-          : { line: fileLines.length, ch: 0 };
-
-      editor.replaceRange(`${sectionContents}\n`, from, to);
+    const fileLines = fileContents.split("\n");
+    if (update.rangesToUpdate.length === 0) {
+      const to = getEditorEndPosition(fileLines);
+      editor.replaceRange(
+        getAppendText(fileContents, update.managedSection),
+        to,
+        to
+      );
       return true;
     }
 
-    const pos = { line: fileLines.length, ch: 0 };
-    editor.replaceRange(`\n\n${sectionContents}`, pos, pos);
+    [...update.rangesToUpdate]
+      .sort((left, right) => right.startLine - left.startLine)
+      .forEach((range) => {
+        const replacementText =
+          update.replacementRange && isSameRange(range, update.replacementRange)
+            ? getReplacementText(fileLines, range, update.managedSection)
+            : "";
+        editor.replaceRange(
+          replacementText,
+          { line: range.startLine, ch: 0 },
+          getEditorRangeEndPosition(fileLines, range)
+        );
+      });
     return true;
   }
 
-  if (logbookSectionLineNum !== -1) {
-    const prefix = fileLines.slice(0, logbookSectionLineNum);
-    const suffix =
-      nextSectionLineNum !== -1 ? fileLines.slice(nextSectionLineNum) : [];
-    const currentSection = fileLines
-      .slice(
-        logbookSectionLineNum,
-        nextSectionLineNum !== -1 ? nextSectionLineNum : fileLines.length
-      )
-      .join("\n")
-      .trimEnd();
-
-    if (currentSection === sectionContents.trimEnd()) {
-      return false;
-    }
-
-    await vault.process(file, () =>
-      [...prefix, sectionContents, ...suffix].join("\n")
-    );
-    return true;
-  }
-
-  await vault.process(file, () => [...fileLines, "", sectionContents].join("\n"));
+  await vault.process(file, () => update.contents);
   return true;
 }
 
-export function getSectionContents(
-  fileContents: string,
-  heading: string
+function getReplacementText(
+  fileLines: string[],
+  range: SectionRange,
+  managedSection: string
 ): string {
-  const headingLevel = getHeadingLevel(heading);
-  if (!headingLevel) {
-    return "";
-  }
-
-  const fileLines = fileContents.split("\n");
-  let sectionLineNum = -1;
-  let nextSectionLineNum = fileLines.length;
-
-  for (let i = 0; i < fileLines.length; i++) {
-    if (fileLines[i].trim() === heading) {
-      sectionLineNum = i;
-    } else if (sectionLineNum !== -1) {
-      const currLevel = getHeadingLevel(fileLines[i]);
-      if (currLevel && currLevel <= headingLevel) {
-        nextSectionLineNum = i;
-        break;
-      }
-    }
-  }
-
-  if (sectionLineNum === -1) {
-    return "";
-  }
-
-  return fileLines.slice(sectionLineNum, nextSectionLineNum).join("\n");
+  const suffix = range.endLine < fileLines.length ? "\n" : "";
+  return `${managedSection}${suffix}`;
 }
 
-export function countThingsTasksInSection(
-  fileContents: string,
-  heading: string
-): number {
-  const sectionContents = getSectionContents(fileContents, heading);
-  if (!sectionContents) {
-    return 0;
+function getEditorEndPosition(fileLines: string[]): { line: number; ch: number } {
+  const lastLine = Math.max(0, fileLines.length - 1);
+  return { line: lastLine, ch: fileLines[lastLine].length };
+}
+
+function getEditorRangeEndPosition(
+  fileLines: string[],
+  range: SectionRange
+): { line: number; ch: number } {
+  if (range.endLine < fileLines.length) {
+    return { line: range.endLine, ch: 0 };
   }
 
-  return sectionContents
-    .split("\n")
-    .filter((line) => /^- \[[ xXcC]\] .*things:\/\/\/show\?id=/.test(line))
-    .length;
-}
\ No newline at end of file
+  return getEditorEndPosition(fileLines);
+}
diff --git a/test/textUtils.test.ts b/test/textUtils.test.ts
new file mode 100644
index 0000000..dcde1ad
--- /dev/null
+++ b/test/textUtils.test.ts
@@ -0,0 +1,186 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  countThingsTasksInSection,
+  LOGBOOK_SECTION_END_MARKER,
+  LOGBOOK_SECTION_START_MARKER,
+  updateSectionContents,
+} from "../src/logbookSection";
+
+const currentSection = [
+  "### Things Daily Log",
+  "",
+  "#### Mindful",
+  "- [x] [Task A](things:///show?id=task-a) #things/mind",
+  "\t## Daily summary",
+  "\t-",
+  "",
+  "#### Body",
+  "- [x] [Task B](things:///show?id=task-b) #things/life",
+].join("\n");
+
+const oldSection = [
+  "### Daily_Things3",
+  "",
+  "#### Mindful",
+  "- [x] [Task A](things:///show?id=task-a) #things/mind",
+  "\t## Daily summary",
+  "\t-",
+  "",
+  "#### Body",
+  "- [x] [Task B](things:///show?id=task-b) #things/life",
+].join("\n");
+
+const defaultSection = [
+  "## Things",
+  "### Mindful",
+  "- [x] [Task A](things:///show?id=task-a) #things/mind",
+  "\t## Daily summary",
+  "\t-",
+  "### Body",
+  "- [x] [Task B](things:///show?id=task-b) #things/life",
+].join("\n");
+
+test("marks a newly appended logbook section", () => {
+  const result = updateSectionContents("# Journal", "### Things Daily Log", currentSection);
+
+  assert.equal(result.didChange, true);
+  assert.equal(
+    result.contents,
+    [
+      "# Journal",
+      "",
+      LOGBOOK_SECTION_START_MARKER,
+      currentSection,
+      LOGBOOK_SECTION_END_MARKER,
+    ].join("\n")
+  );
+});
+
+test("replaces an existing marked logbook section after a heading rename", () => {
+  const fileContents = [
+    "# Journal",
+    "",
+    LOGBOOK_SECTION_START_MARKER,
+    oldSection,
+    LOGBOOK_SECTION_END_MARKER,
+    "",
+    "Personal note",
+  ].join("\n");
+
+  const result = updateSectionContents(
+    fileContents,
+    "### Things Daily Log",
+    currentSection
+  );
+
+  assert.equal(result.didChange, true);
+  assert.match(result.contents, /### Things Daily Log/);
+  assert.doesNotMatch(result.contents, /### Daily_Things3/);
+  assert.match(result.contents, /Personal note/);
+  assert.equal(countOccurrences(result.contents, "things:///show?id=task-a"), 1);
+});
+
+test("leaves an unchanged marked logbook section untouched", () => {
+  const fileContents = [
+    "# Journal",
+    "",
+    LOGBOOK_SECTION_START_MARKER,
+    currentSection,
+    LOGBOOK_SECTION_END_MARKER,
+  ].join("\n");
+
+  const result = updateSectionContents(
+    fileContents,
+    "### Things Daily Log",
+    currentSection
+  );
+
+  assert.equal(result.didChange, false);
+  assert.equal(result.contents, fileContents);
+});
+
+test("consolidates unmarked legacy duplicate logbook sections", () => {
+  const fileContents = [
+    "# Journal",
+    "",
+    "## Things3",
+    "#_things3",
+    "",
+    currentSection,
+    "",
+    oldSection,
+    "",
+    defaultSection,
+    "",
+    "## Notes",
+    "Keep this.",
+  ].join("\n");
+
+  const result = updateSectionContents(
+    fileContents,
+    "### Things Daily Log",
+    currentSection
+  );
+
+  assert.equal(result.didChange, true);
+  assert.match(result.contents, /## Things3/);
+  assert.match(result.contents, /#_things3/);
+  assert.match(result.contents, /### Things Daily Log/);
+  assert.doesNotMatch(result.contents, /### Daily_Things3/);
+  assert.doesNotMatch(result.contents, /\n## Things\n### Mindful/);
+  assert.match(result.contents, /## Notes\nKeep this\./);
+  assert.equal(countOccurrences(result.contents, "things:///show?id=task-a"), 1);
+  assert.equal(countOccurrences(result.contents, "things:///show?id=task-b"), 1);
+});
+
+test("uses a legacy generated section as the rename target when the new heading is absent", () => {
+  const fileContents = ["# Journal", "", oldSection].join("\n");
+
+  const result = updateSectionContents(
+    fileContents,
+    "### Things Daily Log",
+    currentSection
+  );
+
+  assert.equal(result.didChange, true);
+  assert.match(result.contents, /### Things Daily Log/);
+  assert.doesNotMatch(result.contents, /### Daily_Things3/);
+  assert.equal(countOccurrences(result.contents, "things:///show?id=task-a"), 1);
+});
+
+test("does not treat user prose with a Things link as a generated section", () => {
+  const fileContents = [
+    "# Journal",
+    "",
+    "## Related Things",
+    "Remember why this task mattered.",
+    "- [x] [Task A](things:///show?id=task-a)",
+  ].join("\n");
+
+  const result = updateSectionContents(
+    fileContents,
+    "### Things Daily Log",
+    currentSection
+  );
+
+  assert.equal(result.didChange, true);
+  assert.match(result.contents, /## Related Things/);
+  assert.match(result.contents, /Remember why this task mattered\./);
+  assert.equal(countOccurrences(result.contents, "things:///show?id=task-a"), 2);
+});
+
+test("counts tasks in the marked logbook section after a heading rename", () => {
+  const fileContents = [
+    LOGBOOK_SECTION_START_MARKER,
+    oldSection,
+    LOGBOOK_SECTION_END_MARKER,
+  ].join("\n");
+
+  assert.equal(countThingsTasksInSection(fileContents, "### Things Daily Log"), 2);
+});
+
+function countOccurrences(text: string, pattern: string): number {
+  return text.split(pattern).length - 1;
+}
diff --git a/versions.json b/versions.json
index 7081ef4..4b44d55 100644
--- a/versions.json
+++ b/versions.json
@@ -15,5 +15,6 @@
   "1.6.7": "1.13.1",
   "1.6.8": "1.12.0",
   "1.7.0": "1.12.0",
-  "1.7.1": "1.12.0"
-}
\ No newline at end of file
+  "1.7.1": "1.12.0",
+  "1.8.0": "1.12.0"
+}