Report config-remote-sync changes that were not written back

[ilyakuz-db]

Stacked on #6138 — review that first. Based on its branch so this diff shows only the reporting change; rebase onto main once #6138 merges.

Problem

config-remote-sync leaves a change unapplied when it cannot be attributed to a single source location. That is the right call — the command runs unattended, and a guessed location is worse than nothing. But every drop path is a log.Debugf, while the command still prints the full detected changeset and exits 0.

So a run that dropped an edit is indistinguishable from one that applied it, and the in-workspace UI reports "written back" for changes that were not. split/keyed_rename in this repo has been dropping two changes with no visible signal.

Solution

ResolveChanges returns the skipped changes alongside the resolved ones, and the caller reports them: a Not written back section in the text output, a skipped array in the JSON output (omitted when empty, so existing consumers are unaffected), a warn-level log line per drop, and a skipped_changes_count telemetry counter.

Only paths where a real user edit is discarded are counted. The OperationRemove-on-an-undefined-field path is deliberately excluded — a field absent from config has nothing to remove, so that drop is correct rather than a lost edit, and counting it would fire on ordinary runs.

Tests

split/keyed_rename already triggers the unpaired-rename path, so it gains the reporting assertions rather than a new directory — its golden previously showed two changes as detected with no indication they were dropped. It now asserts the text section, and a second run with -o json asserts the skipped array. No other golden changes.

[github-actions]

Approval status: pending

/acceptance/bundle/ - needs approval

4 files changed
Suggested: @pietern
Also eligible: @denik, @andrewnester, @anton-107, @janniklasrose, @lennartkats-db, @shreyas-goenka

/bundle/ - needs approval

5 files changed
Suggested: @pietern
Also eligible: @denik, @andrewnester, @anton-107, @janniklasrose, @lennartkats-db, @shreyas-goenka

/cmd/bundle/ - needs approval

Files: cmd/bundle/config_remote_sync.go
Suggested: @pietern
Also eligible: @denik, @andrewnester, @anton-107, @janniklasrose, @lennartkats-db, @shreyas-goenka

/libs/telemetry/ - needs approval

Files: libs/telemetry/protos/bundle_config_remote_sync.go
Eligible: @simonfaltum, @renaudhartert-db, @hectorcast-db, @parthban-db, @tanmay-db, @Divyansh-db, @tejaskochar-db, @mihaimitrea-db, @chrisst, @rauchy

_{Any maintainer (@andrewnester, @anton-107, @denik, @pietern, @shreyas-goenka, @simonfaltum, @renaudhartert-db, @janniklasrose, @lennartkats-db) can approve all areas.
See OWNERS for ownership rules.}

[eng-dev-ecosystem-bot]

Integration test report

Commit: 9fb79e3

Run: 30863374466

	Env	💚​RECOVERED	🙈​SKIP	✅​pass	🙈​skip	Time
💚​	aws linux	4	4	334	1079	5:22
💚​	aws windows	4	4	324	1081	10:03
💚​	azure linux	4	4	334	1078	5:18
💚​	azure windows	4	4	324	1080	7:22
💚​	gcp linux	1	5	333	1080	5:34
💚​	gcp windows	1	5	323	1082	9:30

8 interesting tests: 4 RECOVERED, 4 SKIP

	Test Name	aws linux	aws windows	azure linux	azure windows	gcp linux	gcp windows
💚​	TestAccept	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R
🙈​	TestAccept/bundle/invariant/no_drift	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
🙈​	TestAccept/bundle/resources/vector_search_endpoints/drift/recreated_same_name	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
🙈​	TestAccept/bundle/resources/vector_search_indexes/recreate/embedding_dimension	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
🙈​	TestAccept/ssh/connection	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
💚​	TestFetchRepositoryInfoAPI_FromRepo	💚​R	💚​R	💚​R	💚​R	🙈​S	🙈​S
💚​	TestFetchRepositoryInfoAPI_FromRepo/root	💚​R	💚​R	💚​R	💚​R
💚​	TestFetchRepositoryInfoAPI_FromRepo/subdir	💚​R	💚​R	💚​R	💚​R

Top 6 slowest tests (at least 2 minutes):

duration	env	testname
8:52	aws windows	TestAccept
8:21	gcp windows	TestAccept
6:20	azure windows	TestAccept
3:12	gcp linux	TestAccept
2:57	aws linux	TestAccept
2:54	azure linux	TestAccept