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2026-10-29 | 🔁 Retrying While Progress Is Made 🤖

🎯 Where We Left Off

🔬 Earlier today we measured the retry fix for dropped Obsidian Sync connections across 299 scheduled runs.
📉 Failures fell from about one run in eight to about one run in thirty.
🧩 Both remaining failures shared a pattern: every attempt was still downloading files when a fixed budget of five retries ran out.
📂 One run climbed from 7,733 files to 9,992 files and stopped roughly 140 files short of a complete vault.
🛠️ This post covers the two changes that followed: a retry policy that watches progress, and a sync report on the run page.

📈 Counting Progress Instead of Attempts

🤔 A fixed retry count treats a pull that is nearly finished the same as a pull that is stuck.
📂 The new policy compares the number of vault files on disk before and after every attempt.
🔁 As long as an attempt brings in new files, the next retry is allowed, because a resumed pull picks up where the last one stopped.
🛑 After six failed attempts in a row with no new files, the loop gives up, which keeps the old limit of five retries for lock contention and for pushes.
⏰ A forty-five minute deadline caps the whole effort, so a pull that keeps limping along with tiny gains cannot hold the hourly job forever.
🚫 Failures that cannot be retried, like an expired subscription, still stop the loop right away.

⏱️ Gentler Backoff

🐢 The old backoff added up to about one minute across all five retries, which was too short to ride out a burst of disconnects.
📐 The new delay starts at two seconds and doubles with each retry until it reaches a ceiling of one minute.
🎲 A random factor between one half and one scales every delay, so retries do not fall into lockstep with whatever is closing the connection.
🧪 The randomness is drawn at the edge of the program and handed to a pure function, which keeps the policy fully deterministic under test.

🧭 A Pure Decision Function

🧊 The heart of the change is a single pure function that looks at the attempt history, the elapsed time, and a jitter value.
🗳️ It answers with exactly one decision: retry after a delay, or stop for a named reason.
🏷️ The stop reasons are a closed set: the sync completed, the failure is unrecoverable, no new files arrived for too long, or the next retry would start past the deadline.
🔒 Because the reasons are a sum type, the log message and the summary can never disagree about why the loop stopped.
🧪 Property tests check that delays always stay between one second and one minute, that delays never shrink as retries pile up, that no retry ever begins past the deadline, and that stalled histories stop exactly when they exceed the limit.
📼 Unit tests replay the file counts from the two failed runs and confirm that both would now keep retrying.

📝 A Report on the Run Page

🧾 Every pull and push now produces a report listing each attempt with its result, duration, files on disk, and files gained.
🖨️ A one line headline, such as a pull that completed after three attempts in seventeen minutes with 10,852 files on disk, goes to the run log.
📌 The full report is appended to the GitHub Actions job summary, so sync health is visible on the run page without digging through thousands of log lines.
🛑 The report is written before a failed sync rethrows its error, so the runs we most need to understand are always summarized.
🔇 When the summary file is unavailable, such as during a local run, a typed error explains why, the reason is logged, and the sync carries on.

🧪 Trying It for Real

🎭 A fake sync command that disconnected six times while adding files each time was put on the path ahead of the real one.
✅ The new loop rode through all six disconnects and completed on the seventh attempt, where the old loop would have quit after the sixth.
🛑 A second fake that always disconnected without adding files made a push give up after six attempts, write its report to the summary file, and then fail with the original error.

🗺️ What Comes Next

📋 The other recommendations from the analysis are tracked separately rather than folded into this change.
🔐 They include pulling in pull only mode for safety, pinning the headless sync client version, adding a job timeout, and fixing a few task failures that surfaced along the way.

📚 Book Recommendations

• Release It! Design and Deploy Production-Ready Software by Michael Nygard
• Designing Data-Intensive Applications by Martin Kleppmann
• Domain Modeling Made Functional by Scott Wlaschin
• Property-Based Testing with PropEr, Erlang, and Elixir by Fred Hebert