Deduplicate tool names with empty results in call summary

[PratikDhanave]

When ToolResultStrategy collapses an old tool-call group, DefaultToolCallFormatter lists each distinct tool name once. The deduplication guard keyed off the groupedResults map:

if _, ok := groupedResults[functionCall.name]; !ok {
    orderedNames = append(orderedNames, functionCall.name)
}
...
if result != "" {
    groupedResults[functionCall.name] = append(groupedResults[functionCall.name], result)
}

But groupedResults is only written when a result is non-empty. So repeated calls to the same tool whose results are empty — an empty-string result, or an orphaned call with no matching result content — never register the name in the map, and each call re-appends the name to orderedNames. The summary then emits the same name: line twice:

[Tool Calls]
notify:
notify:

This directly contradicts the formatter’s stated design (the doc comment promises "deduplication ... for repeated tool names"). Empty/absent results are realistic for tool-heavy conversations — e.g. parallel calls to a fire-and-forget tool (notify, log) that returns an empty string — which is exactly the input this formatter receives when collapsing old groups.

Fix

Track seen names in a dedicated set so deduplication is independent of whether a result is present:

seenNames := make(map[string]bool)
...
if !seenNames[functionCall.name] {
    seenNames[functionCall.name] = true
    orderedNames = append(orderedNames, functionCall.name)
}

Test

TestDefaultToolCallFormatter_DedupsRepeatedNamesWithEmptyResults formats a group with two parallel calls to the same tool, both with empty results, and asserts the name is listed once. It fails on the old code ("[Tool Calls]\nnotify:\nnotify:") and passes with the fix.

[Copilot]

Pull request overview

Fixes a bug in the compaction tool-call summary formatter where repeated tool calls with empty/absent results could cause the same tool name to be emitted multiple times, despite the formatter’s intended deduplication behavior.

Changes:

• Deduplicate tool names using a dedicated seenNames set, independent of whether any non-empty results were recorded.
• Add a regression test ensuring repeated tool calls with empty results only emit the tool name once.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
agent/compaction/toolresult.go	Uses a separate seenNames map to ensure tool-name deduplication works even when results are empty/missing.
agent/compaction/compaction_test.go	Adds a targeted test covering the empty-result deduplication regression case.

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