feat(core): record overflow as a compaction reason

packages/client/src/effect/api/api.ts

@@ -1174,7 +1174,7 @@ export type SessionLogOutput =
             | undefined
           readonly data: {
             readonly sessionID: Session.ID
-            readonly reason: "auto" | "manual"
+            readonly reason: "auto" | "manual" | "overflow"
             readonly recent: string
             readonly inputID?: SessionMessage.ID | undefined
           }
@@ -1193,7 +1193,7 @@ export type SessionLogOutput =
             | undefined
           readonly data: {
             readonly sessionID: Session.ID
-            readonly reason: "auto" | "manual"
+            readonly reason: "auto" | "manual" | "overflow"
             readonly model?: Model.Ref | undefined
             readonly providerState?: SessionMessage.ProviderState | undefined
             readonly providerContext?:
@@ -1237,7 +1237,7 @@ export type SessionLogOutput =
             | undefined
           readonly data: {
             readonly sessionID: Session.ID
-            readonly reason: "auto" | "manual"
+            readonly reason: "auto" | "manual" | "overflow"
             readonly error: { readonly type: string; readonly message: string; readonly status?: number | undefined }
             readonly inputID?: SessionMessage.ID | undefined
             readonly cost?: (number & Brand.Brand<"Money.USD">) | undefined

packages/client/src/promise/generated/types.ts

@@ -141,7 +141,7 @@ export type SessionMessageCompactionRunning = {
   metadata?: { [x: string]: JsonValue }
   time: { created: number }
   status: "running"
-  reason: "auto" | "manual"
+  reason: "auto" | "manual" | "overflow"
   summary: string
   recent: string
 }
@@ -534,7 +534,7 @@ export type SessionMessageCompactionFailed = {
   metadata?: { [x: string]: JsonValue }
   time: { created: number }
   status: "failed"
-  reason: "auto" | "manual"
+  reason: "auto" | "manual" | "overflow"
   error: SessionStructuredError
   cost?: MoneyUSD
   tokens?: TokenUsageInfo
@@ -788,7 +788,7 @@ export type SessionCompactionStarted = {
   type: "session.compaction.started"
   durable: { aggregateID: string; seq: number; version: 1 }
   location?: LocationRef
-  data: { sessionID: string; reason: "auto" | "manual"; recent: string; inputID?: string }
+  data: { sessionID: string; reason: "auto" | "manual" | "overflow"; recent: string; inputID?: string }
 }
 
 export type SessionCompactionFailed = {
@@ -800,7 +800,7 @@ export type SessionCompactionFailed = {
   location?: LocationRef
   data: {
     sessionID: string
-    reason: "auto" | "manual"
+    reason: "auto" | "manual" | "overflow"
     error: SessionStructuredError
     inputID?: string
     cost?: MoneyUSD
@@ -1776,7 +1776,7 @@ export type SessionMessageCompactionCompleted = {
   metadata?: { [x: string]: JsonValue }
   time: { created: number }
   status: "completed"
-  reason: "auto" | "manual"
+  reason: "auto" | "manual" | "overflow"
   model?: ModelRef
   providerState?: SessionMessageProviderState
   summary: string
@@ -1795,7 +1795,7 @@ export type SessionCompactionEnded = {
   location?: LocationRef
   data: {
     sessionID: string
-    reason: "auto" | "manual"
+    reason: "auto" | "manual" | "overflow"
     model?: ModelRef
     providerState?: SessionMessageProviderState1
     providerContext?: SessionProviderContext
@@ -3226,7 +3226,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "running"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly summary: string
               readonly recent: string
             }
@@ -3236,7 +3236,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "completed"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string }
               readonly providerState?: { readonly [x: string]: JsonValue }
               readonly summary: string
@@ -3267,7 +3267,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "failed"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly error: { readonly type: string; readonly message: string; readonly status?: number }
               readonly cost?: number
               readonly tokens?: {
@@ -3543,7 +3543,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "running"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly summary: string
               readonly recent: string
             }
@@ -3553,7 +3553,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "completed"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string }
               readonly providerState?: { readonly [x: string]: JsonValue }
               readonly summary: string
@@ -3584,7 +3584,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "failed"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly error: { readonly type: string; readonly message: string; readonly status?: number }
               readonly cost?: number
               readonly tokens?: {
@@ -3860,7 +3860,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "running"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly summary: string
               readonly recent: string
             }
@@ -3870,7 +3870,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "completed"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string }
               readonly providerState?: { readonly [x: string]: JsonValue }
               readonly summary: string
@@ -3901,7 +3901,7 @@ export type SessionImportInput = {
               readonly metadata?: { readonly [x: string]: JsonValue }
               readonly time: { readonly created: number }
               readonly status: "failed"
-              readonly reason: "auto" | "manual"
+              readonly reason: "auto" | "manual" | "overflow"
               readonly error: { readonly type: string; readonly message: string; readonly status?: number }
               readonly cost?: number
               readonly tokens?: {

packages/core/src/session/compaction.ts

@@ -376,7 +376,11 @@ export const layer = Layer.effect(
       const context = trigger.context
       // The runner opened the manual compaction's message when it delivered the `/compact` item.
       if (trigger.reason !== "manual") {
-        yield* bus.publish(SessionEvent.Compaction.Started, { sessionID: context.session.id, reason: "auto", recent })
+        yield* bus.publish(SessionEvent.Compaction.Started, {
+          sessionID: context.session.id,
+          reason: trigger.reason,
+          recent,
+        })
       }
       if (prepared.event.result) return yield* fromHook(context, prepared.event.result, recent)
 
@@ -614,13 +618,12 @@ export const layer = Layer.effect(
     ): Effect.fn.Return<Outcome> {
       const context = trigger.context
       const sessionID = context.session.id
-      const reason = trigger.reason === "manual" ? "manual" : "auto"
       const usage = spent.get(sessionID)
 
       if ("error" in outcome) {
         yield* bus.publish(SessionEvent.Compaction.Failed, {
           sessionID,
-          reason,
+          reason: trigger.reason,
           inputID: trigger.reason === "manual" ? trigger.inputID : undefined,
           error: outcome.error,
           ...usage,
@@ -632,7 +635,7 @@ export const layer = Layer.effect(
         SessionEvent.Compaction.Ended,
         {
           sessionID,
-          reason,
+          reason: trigger.reason,
           model: context.model.ref,
           providerState: outcome.providerState,
           providerContext: outcome.providerContext,

packages/core/test/session-runner.test.ts

@@ -3234,11 +3234,14 @@ describe("SessionRunnerLLM", () => {
     expect(userTexts(s.requests[1]).at(-1)).toContain("## Objective")
     expect(userTexts(s.requests[2])[0]).toContain("<summary>\n## Objective\n- Recover overflow\n</summary>")
     expect(yield* s.context).toMatchObject([
-      { type: "compaction", summary: "## Objective\n- Recover overflow" },
+      { type: "compaction", reason: "overflow", summary: "## Objective\n- Recover overflow" },
       { type: "assistant", finish: "stop" },
     ])
     yield* replaySessionProjection(sessionID)
-    expect(yield* s.context).toMatchObject([{ type: "compaction" }, { type: "assistant", finish: "stop" }])
+    expect(yield* s.context).toMatchObject([
+      { type: "compaction", reason: "overflow" },
+      { type: "assistant", finish: "stop" },
+    ])
   })
 
   scenario("refreshes preparation after overflow compaction without promoting new input", function* (s) {
@@ -3476,13 +3479,13 @@ describe("SessionRunnerLLM", () => {
       expect.objectContaining({
         type: "compaction",
         status: "failed",
-        reason: "auto",
+        reason: "overflow",
         error: { type: "provider.error", message: "summary unavailable" },
       }),
     )
     expect(context.slice(-3)).toMatchObject([
       Expected.user("Continue"),
-      { type: "compaction", status: "failed", reason: "auto" },
+      { type: "compaction", status: "failed", reason: "overflow" },
       { type: "assistant", finish: "error", error: { message: "prompt too long" } },
     ])
   })
@@ -3509,7 +3512,7 @@ describe("SessionRunnerLLM", () => {
       expect.objectContaining({
         type: "compaction",
         status: "failed",
-        reason: "auto",
+        reason: "overflow",
         error: { type: "compaction.interrupted", message: "Compaction was interrupted" },
       }),
     )

packages/schema/src/session-event.ts

@@ -588,7 +588,7 @@ export namespace Compaction {
     ...options,
     schema: {
       ...Base,
-      reason: Schema.Literals(["auto", "manual"]),
+      reason: SessionMessage.CompactionRunning.fields.reason,
       recent: Schema.String,
       inputID: SessionMessage.ID.pipe(optional),
     },

packages/schema/src/session-message.ts

@@ -237,6 +237,9 @@ export const Assistant = Schema.Struct({
 
 const CompactionBase = { type: Schema.tag("compaction"), ...Base }
 
+/** `overflow`: the provider rejected the request as too long, before our own size check called for it. */
+const CompactionReason = Schema.Literals(["auto", "manual", "overflow"])
+
 /** Usage of the compaction request itself, not the size of the resulting context. */
 const CompactionUsage = {
   cost: Money.USD.pipe(optional),
@@ -247,7 +250,7 @@ export interface CompactionRunning extends Schema.Schema.Type<typeof CompactionR
 export const CompactionRunning = Schema.Struct({
   ...CompactionBase,
   status: Schema.tag("running"),
-  reason: Schema.Literals(["auto", "manual"]),
+  reason: CompactionReason,
   summary: Schema.String,
   recent: Schema.String,
 }).annotate({ identifier: "Session.Message.Compaction.Running" })
@@ -256,7 +259,7 @@ export interface CompactionCompleted extends Schema.Schema.Type<typeof Compactio
 export const CompactionCompleted = Schema.Struct({
   ...CompactionBase,
   status: Schema.tag("completed"),
-  reason: Schema.Literals(["auto", "manual"]),
+  reason: CompactionReason,
   model: Model.Ref.pipe(optional),
   providerState: ProviderState.pipe(optional),
   summary: Schema.String,
@@ -269,7 +272,7 @@ export interface CompactionFailed extends Schema.Schema.Type<typeof CompactionFa
 export const CompactionFailed = Schema.Struct({
   ...CompactionBase,
   status: Schema.tag("failed"),
-  reason: Schema.Literals(["auto", "manual"]),
+  reason: CompactionReason,
   error: SessionError.Error,
   ...CompactionUsage,
 }).annotate({ identifier: "Session.Message.Compaction.Failed" })

packages/tui/src/routes/session/index.tsx

@@ -2052,6 +2052,9 @@ function CompactionMessage(props: { message: Extract<SessionMessageInfo, { type:
               ? "Provider compaction"
               : "Compaction"}
           </text>
+          <Show when={props.message.reason === "overflow"}>
+            <text fg={color()}>· context overflow</text>
+          </Show>
           <Show when={cancelled()}>
             <text fg={color()}>· cancelled</text>
           </Show>