Fix: Prevent duplicate sync markers when syncing to markdown file

[Copilot]

Problem

When syncing deeplinks to a markdown file multiple times, especially after deleting deeplinks from the app, the sync operation would append content to the existing file instead of overwriting it. This caused:

• Multiple <!-- End of Deepr Sync Data --> markers appearing in the file
• Orphaned deeplink data from previous syncs remaining in the file
• Duplicate headers and table structures
• Corrupted markdown file structure

Example of the bug:

After first sync with 3 deeplinks, then deleting 2 deeplinks and syncing again:

<!-- Headers and data from first sync -->
| Link1 | ... |
| Link2 | ... |  ⚠️ Deleted but still in file
| Link3 | ... |  ⚠️ Deleted but still in file
<!-- End of Deepr Sync Data -->

<!-- Headers and data from second sync (appended) -->
| Link1 | ... |
<!-- End of Deepr Sync Data -->  ⚠️ Duplicate marker

Root Cause

The ContentResolver.openOutputStream(Uri) method without a mode parameter opens the output stream in append mode by default. This caused each sync operation to add new content to the end of the existing file rather than replacing it.

Solution

Changed line 38 in SyncRepositoryImpl.kt to use the two-parameter version of openOutputStream() with the "wt" mode (write-truncate):

- context.contentResolver.openOutputStream(filePath.toUri())?.use {
+ context.contentResolver.openOutputStream(filePath.toUri(), "wt")?.use {

The "wt" mode explicitly truncates (clears) the file before writing, ensuring a clean write operation that completely replaces the file content on each sync.

Impact

• ✅ Minimal change: 1 line, 5 characters added
• ✅ No breaking changes or side effects
• ✅ Directly addresses the root cause
• ✅ Each sync now produces a clean file with current data only

Testing

To verify the fix:

1. Sync deeplinks to a markdown file
2. Delete some deeplinks from the app
3. Sync again
4. Verify the file contains only current deeplinks with exactly one <!-- End of Deepr Sync Data --> marker

Fixes the issue described in the original report where duplicate end markers were created between multiple sync operations.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• dl.google.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -Xmx2048m -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-8.13-bin/5xuhj0ry160q40clulazy9h7d/gradle-8.13/lib/gradle-daemon-main-8.13.jar -javaagent:/home/REDACTED/.gradle/wrapper/dists/gradle-8.13-bin/5xuhj0ry160q40clulazy9h7d/gradle-8.13/lib/agents/gradle-instrumentation-agent-8.13.jar org.gradle.launcher.daemon.bootstrap.GradleDaemon 8.13 (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>If you sync to .md then delete deeplink(s) and sync again, the link is not fully removed but...</issue_title>
<issue_description>It creates a new <!-- End of Deepr Sync Data --> and writes part of the deeplink between the now 2 <!-- End of Deepr Sync Data --></issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #121

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