Revert log sinks to service configuration

[javuto]

Revert log sinks to service configuration

Problem

Once a log sink was edited through the admin UI (source = "db"), there
was no way to roll it back to the values defined in the YAML/env/flags
service configuration without manually editing the database or the YAML
file and restarting. Operators who wanted to discard their UI edits and
return to the seeded config had no self-service path.

Solution

Add a "Revert" button on each edited sink row that flips source back
to "service", then re-syncs the config from the current service
configuration during the next hot-reload — no restart, no YAML editing,
no backend access needed.

How it works

1. Operator clicks "Revert" on a sink row with source = "db".
   A confirm dialog explains the config will be re-synced from the
   YAML/flags on the next Apply.

2. API: POST /api/v1/log-sinks/{id}/revert calls
   LogSinksManager.RevertToService(id) which sets source = "service"
   on the row. The config blob is not changed here — only the source
   flag. The sync happens in the TLS process which has access to the
   resolved service parameters.

3. Operator clicks "Apply changes" — queues a reload-log-sinks
   service command to osctrl-tls.

4. TLS hot-reload: the ActionReloadLogSinks handler now calls
   Seed(flagParams, ...) before BuildExportersForEnvironments. Since
   the reverted row now has source = "service", seedRow's sync step
   overwrites the config with the current service-config values
   (flags, env vars, or YAML). The exporters are then rebuilt from the
   freshly synced rows and atomically swapped in.

5. Seed sinks (source = "service") do not show the Revert button
   — there is nothing to revert. The existing seedRow sync keeps
   them up to date on every boot and reload.

Changes

Backend

pkg/logsinks/logsinks.go:

• New RevertToService(id uint) error method: flips source from
  "db" to "service". No-op if already "service" or legacy
  "yaml". Returns ErrSinkNotFound for missing rows.

cmd/tls/main.go — ActionReloadLogSinks handler:

• Added sinksMgr.Seed(flagParams, ...) call before
  BuildExportersForEnvironments so reverted rows get their config
  re-synced from the current service configuration during the reload.
  Previously the reload only read existing DB rows without re-seeding.

cmd/api/handlers/log_sinks.go:

• New LogSinksRevertHandler — POST /api/v1/log-sinks/{id}/revert.
  Admin-only, audit-logged. Returns the updated row (secrets redacted).

cmd/api/main.go:

• Registered the revert route alongside the other log-sinks CRUD
  routes, gated by serviceConfigEnabled.

Frontend

frontend/src/api/log-sinks.ts:

• New revertLogSink(id) function.

frontend/src/features/log-sinks/LogSinksPage.tsx:

• revertMutation (useMutation) calling revertLogSink.
• "Revert" button in the table row action cell, shown only when
  source === 'db'. Styled as a muted secondary action
  (text-[color:var(--text-2)] hover:bg-[color:var(--bg-2)]) to
  distinguish it from Edit (primary) and Delete (danger).
• Confirm dialog: "Revert '{name}' to service config? The config will
  be re-synced from the YAML/flags on the next Apply."
• Tooltip: "Reset this sink back to the service configuration values.
  Takes effect on the next Apply."

Tests

pkg/logsinks/logsinks_test.go — TestRevertToService:

• Creates a sink (source defaults to "db"), reverts it, verifies
  source is now "service". Verifies revert is idempotent (no-op on
  already-service rows). Verifies missing row returns
  ErrSinkNotFound.

frontend/src/features/log-sinks/LogSinksPage.test.tsx — two new tests:

• "shows a Revert button for edited sinks and calls revertLogSink" —
  seeds a source: 'db' row, finds the Revert button, clicks it
  (with confirm mocked), verifies revertLogSink was called with
  the right ID.
• "does not show a Revert button for seed sinks" — seeds a
  source: 'service' row, verifies no Revert button is rendered.

Validation

• Go: 44 packages pass, 0 failures.
• Frontend: 242 tests pass (2 new), type check clean.
• All existing log-sinks tests continue to pass unchanged.

Files

Modified (6 files):

• pkg/logsinks/logsinks.go — RevertToService method
• pkg/logsinks/logsinks_test.go — revert test
• cmd/tls/main.go — re-seed during reload
• cmd/api/handlers/log_sinks.go — revert handler
• cmd/api/main.go — route registration
• frontend/src/api/log-sinks.ts — revertLogSink function
• frontend/src/features/log-sinks/LogSinksPage.tsx — revert button
• frontend/src/features/log-sinks/LogSinksPage.test.tsx — 2 tests