feat(realtime): conversation compaction (summarize-then-drop) + OpenAI item.delete/truncate/clear (#10446)

* feat(realtime): add pipeline.compaction config + resolution

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* refactor(realtime): extract itemID helper, reuse in item.retrieve

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* test(realtime): drop duplicate Ginkgo bootstrap, fold specs into openai suite

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): implement conversation.item.delete

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): implement input_audio_buffer.clear

Add a handler for the input_audio_buffer.clear client event that discards
a partially-captured utterance (raw PCM + buffered Opus frames) via a
unit-tested clearInputAudio helper, then acks with input_audio_buffer.cleared.

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): implement conversation.item.truncate (text)

Clears both .Text and .Transcript of the assistant content part at
contentIndex so barge-in truncation also works for audio turns whose
spoken words live in .Transcript.

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): add Conversation.Memory + pair-safe compactionCut

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix(realtime): compactionCut returns 0 for keep<=0 (no-cap sentinel, avoids panic)

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* style(realtime): gofmt compaction test helper closures

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): inject rolling memory into the prompt + summary builders

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): server-side summarize-then-drop compactor

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* test(realtime): unit-test prefixMatches eviction-safety predicate

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat(realtime): resolve summarizer model + schedule compaction per turn

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* docs(realtime): document conversation compaction + new item events

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix(realtime): resolve summary model inside compaction goroutine (lazy, off-path)

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* refactor(realtime): reuse reasoning.ExtractReasoningComplete for summary stripping

Replace the bespoke <think> regex in the compactor with the shared
pkg/reasoning extractor (via spokenReasoningConfig), matching the rest of
the realtime path and covering all reasoning tag families, not just <think>.

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix(config): register pipeline.compaction fields in meta registry

TestAllFieldsHaveRegistryEntries requires every ModelConfig field to have
a UI/meta registry entry; add the four pipeline.compaction.* leaves so they
render with proper labels/descriptions instead of the reflection fallback.

Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>

docs/content/features/openai-realtime.md

@@ -68,6 +68,33 @@ pipeline:
 
 This is applied only to the realtime session's copy of the LLM config, so it does not affect other users of the same model. Leave it unset to use the LLM model config's own reasoning settings.
 
+### Conversation compaction (long sessions on CPU)
+
+By default a realtime session feeds only the last `max_history_items` turns to the LLM; older turns are dropped and forgotten. On CPU, long calls also grow expensive as the prompt fills with verbatim history. Enable `compaction` to instead fold older turns into a rolling summary, so long calls stay cheap without losing earlier context.
+
+Compaction works with two numbers:
+
+- **`max_history_items`** is the *live window* — the recent turns kept verbatim in the prompt.
+- **`compaction.trigger_items`** is the *high-water mark* — let the buffer grow to here, then summarize the overflow (everything above `max_history_items`) into a rolling memory and evict it. It must be greater than `max_history_items`; if it is not, it is clamped up.
+
+The gap between the two controls how often summarization runs: a summary call fires roughly every `(trigger_items - max_history_items)` turns (here, about every 6 turns).
+
+```yaml
+pipeline:
+  max_history_items: 6        # live window — recent turns kept verbatim
+  compaction:
+    enabled: true
+    trigger_items: 12         # summarize overflow back down to max_history_items
+    summary_model: ""         # optional: a small model for the summary (CPU); default = pipeline LLM
+    max_summary_tokens: 512
+```
+
+{{% notice tip %}}
+On CPU, set `summary_model` to a small, fast model so compaction never competes with the conversation LLM for compute. Left empty, the pipeline's own LLM produces the summary.
+{{% /notice %}}
+
+Clients can also manage history directly via the now-supported `conversation.item.delete`, `conversation.item.truncate`, and `input_audio_buffer.clear` realtime events.
+
 ## Transports
 
 The Realtime API supports two transports: **WebSocket** and **WebRTC**.