[log] Add debug logging to difc/sink_server_ids

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Summary

Adds a debug logger (logSink) to internal/difc/sink_server_ids.go using the project's standard logger.New("difc:sink_server_ids") pattern. This file configures which backend server IDs receive DIFC tag snapshot enrichment in RPC JSONL logs, and previously had no debug visibility.

Changes

File modified: internal/difc/sink_server_ids.go

• Added logger import and var logSink = logger.New("difc:sink_server_ids") declaration
• SetSinkServerIDs: logs input count on entry, logs when config is cleared, logs skipped duplicate IDs, logs final normalized IDs and count after sorting
• IsSinkServerID: logs when a match is found (called frequently, so only logs on positive match to minimize noise)

Logging calls added (5 total)

Location	Message	Purpose
SetSinkServerIDs entry	Setting sink server IDs: input_count=N	Trace configuration calls
SetSinkServerIDs empty case	No sink server IDs provided, clearing configuration	Visible config reset
SetSinkServerIDs loop	Skipping duplicate sink server ID: %s	Debug dedup logic
SetSinkServerIDs end	Sink server IDs configured: count=N, ids=[...]	Final state confirmation
IsSinkServerID match	Sink server ID match: serverID=%s	Trace positive lookups

Logger naming convention

Follows pkg:filename convention: "difc:sink_server_ids" for internal/difc/sink_server_ids.go.

Testing

Enable with DEBUG=difc:* ./awmg --config config.toml to see all difc debug logs including the new sink server ID logs.

Generated by Go Logger Enhancement · ◷

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Pull request overview

Adds standard debug logging to DIFC sink server ID configuration/lookup to improve observability of which backend server IDs get DIFC tag snapshot enrichment in RPC JSONL logs.

Changes:

• Introduces a logSink debug logger using logger.New("difc:sink_server_ids").
• Adds debug logs in SetSinkServerIDs for input size, clears, dedup behavior, and final normalized configuration.
• Adds a debug log in IsSinkServerID on positive matches to trace lookups when enabled.

Comments suppressed due to low confidence (2)

internal/difc/sink_server_ids.go:49

• This final configuration log runs while sinkServerIDsMu is still held (due to the deferred unlock). Since logging performs formatting + I/O when enabled, it’s better to assign sinkServerIDs under lock, release the lock, and then log the configured IDs/count to minimize time spent in the critical section.

	sort.Strings(normalized)
	sinkServerIDs = normalized
	logSink.Printf("Sink server IDs configured: count=%d, ids=%v", len(normalized), normalized)
}

internal/difc/sink_server_ids.go:60

• IsSinkServerID performs debug logging while still holding sinkServerIDsMu.RLock(). When DEBUG is enabled, this adds formatting + I/O into the locked section and can delay writers (SetSinkServerIDs) unnecessarily. Consider checking for a match under lock, unlocking, then logging/returning based on the result to keep the lock hold time minimal.

	for _, sinkServerID := range sinkServerIDs {
		if serverID == sinkServerID {
			logSink.Printf("Sink server ID match: serverID=%s", serverID)
			return true
		}

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