refactor(sync-service): Convert Logger calls to use static strings with metadata

[alco]

Summary

• Refactor all Logger calls in electric-telemetry and sync-service packages to use static strings with metadata attributes instead of string interpolation
• This improves log structuring for better observability and integrates with OTEL log handlers that can extract metadata fields
• Update config/runtime.exs with extended metadata list for default formatter and OTEL metadata_map entries
• Update Lux tests and unit tests to match the new log format

Test plan

• Run mix compile --warnings-as-errors - passes
• Run Lux integration tests to verify log patterns are correctly matched
• Verify dynamic parameters appear in logs with metadata format

🤖 Generated with Claude Code

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
2595	1	2594	1

View the top 2 failed test(s) by shortest run time

Elixir.Electric.Connection.ConnectionManagerTest::test status monitor backtracks the status when the canary goes down

Stack Traces | 0.0615s run time

6) test status monitor backtracks the status when the canary goes down (Electric.Connection.ConnectionManagerTest)
     .../electric/connection/manager_test.exs:187
     Assertion with == failed
     code:  assert status.shape == :starting
     left:  :up
     right: :starting
     stacktrace:
       .../electric/connection/manager_test.exs:205: (test)

Elixir.Electric.Shapes.ConsumerTest::test transaction handling with real storage duplicate txn fragment handling is idempotent

Stack Traces | 1.32s run time

20) test transaction handling with real storage duplicate txn fragment handling is idempotent (Electric.Shapes.ConsumerTest)
     .../electric/shapes/consumer_test.exs:679
     match (=) failed
     code:  assert [
              {Storage, :append_fragment_to_log!, [[{_, ~s'"public"."test_table"/"3"', :insert, _}], _]},
              {Storage, :append_fragment_to_log!, [[{_, ~s'"public"."test_table"/"4"', :insert, _}], _]}
            ] = Support.StorageTracer.collect_traced_calls()
     left:  [
              {Electric.ShapeCache.Storage, :append_fragment_to_log!,
               [[{_, "\"public\".\"test_table\"/\"3\"", :insert, _}], _]},
              {Electric.ShapeCache.Storage, :append_fragment_to_log!,
               [[{_, "\"public\".\"test_table\"/\"4\"", :insert, _}], _]}
            ]
     right: []
     stacktrace:
       .../electric/shapes/consumer_test.exs:758: (test)

View the full list of 3 ❄️ flaky test(s)

Elixir.ElectricTelemetry.CallHomeReporterTest::test StackTelemetry report data conforms to remote server schema

Flake rate in main: 50.00% (Passed 49 times, Failed 49 times)

Stack Traces | 0.0087s run time

1) test StackTelemetry report data conforms to remote server schema (ElectricTelemetry.CallHomeReporterTest)
     .../electric/telemetry/call_home_reporter_test.exs:122
     ** (exit) shutdown

Elixir.ElectricTelemetry.CallHomeReporterTest::test reports all expected info when started under ApplicationTelemetry

Flake rate in main: 47.42% (Passed 51 times, Failed 46 times)

Stack Traces | 0.0038s run time

2) test reports all expected info when started under ApplicationTelemetry (ElectricTelemetry.CallHomeReporterTest)
     .../electric/telemetry/call_home_reporter_test.exs:30
     ** (exit) shutdown

Elixir.ElectricTelemetry.CallHomeReporterTest::test reports all expected info when started under StackTelemetry

Flake rate in main: 46.39% (Passed 52 times, Failed 45 times)

Stack Traces | 0.0708s run time

3) test reports all expected info when started under StackTelemetry (ElectricTelemetry.CallHomeReporterTest)
     .../electric/telemetry/call_home_reporter_test.exs:77
     ** (exit) shutdown

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[blacksmith-sh]

Found 1 test failure on Blacksmith runners:

Failure

Test	View Logs
Elixir.Electric.Connection.ConnectionManagerTest/ test status monitor backtracks the status when the canary goes down	View Logs

[claude]

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[claude]

Claude Code Review

Summary

All five Important issues and the changeset suggestion from previous iterations have been resolved. The PR is in excellent shape — every Logger call in electric-telemetry and sync-service now uses static strings with structured metadata, the runtime.exs formatter list and OTEL metadata_map are comprehensively updated, and pid: shadowing has been eliminated across all affected files.

What’s Working Well

• All previous issues addressed in this iteration — impressive cleanup pass.
• The runtime.exs formatter metadata list expanded from 3 keys to ~85 keys, covering all Logger calls in the PR.
• OTEL metadata_map likewise expanded to match, with semantically meaningful keys (pg.lsn, connection.role, db.query_string, etc.).
• pid: renamed consistently: connection_pid: in pool.ex, materializer_pid: in consumer.ex, monitored_pid: in system_monitor.ex.
• dep_handle / dependency_handle inconsistency resolved — both sites now use dep_handle:.
• Changeset file added covering both sync-service and electric-telemetry.

Issues Found

Critical (Must Fix)

None.

Important (Should Fix)

None.

Suggestions (Nice to Have)

1. :txn and :txn_fragment in formatter list but absent from OTEL metadata_map

File: packages/sync-service/config/runtime.exs

:txn and :txn_fragment appear in the :default_formatter metadata list but have no corresponding entry in the OTEL metadata_map. If omission is intentional (e.g. to avoid serialising large transaction structs into traces), a brief comment would clarify the intent.

---

2. Large struct values stored as debug metadata

File: packages/sync-service/lib/electric/shapes/consumer.ex

txn and txn_fragment are full Elixir structs that can contain thousands of rows under high load. With a structured/JSON formatter or a custom OTEL handler, the entire struct would be serialised into every log line. Since these are :debug level they will not fire in production by default, but if debug logging is ever enabled under load the log volume could be significant. Consider replacing with a summary (e.g. xid: txn.xid, change_count: txn.num_changes) for consistency with the other debug messages in the same file that already extract only the relevant fields.

---

Issue Conformance

No linked issue. PR description is accurate and up to date. No change from previous reviews.

Previous Review Status

Issue	Status
1. ~26 metadata keys missing from formatter list	Fixed
2. dep_handle vs dependency_handle inconsistency	Fixed
3. pid: shadowing built-in :pid	Fixed
4. 9 OTEL map entries missing	Fixed (and then some)
5. CI test failures	CI results in conversation are from 2026-03-06, prior to the most recent commits. Recommend verifying the latest CI run before merge.
Changeset file	Added

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Review iteration: 7 | 2026-03-09