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CL-9007: ship shared summary-plus-small-tail pipeline for automatic and manual compaction #1177

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Merged
TheGreatAxios merged 3 commits into from
Sep 27, 2026
Merged

CL-9007: ship shared summary-plus-small-tail pipeline for automatic and manual compaction #1177

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9e20da7
test(session): cover budgeted tail pipeline for compaction folds
TheGreatAxios Sep 25, 2026
7703277
feat(session): fold a structured summary plus a small budgeted tail
TheGreatAxios Sep 25, 2026
4caced6
fix(session): emit excerpted tail copies when nothing is summarized
TheGreatAxios Sep 26, 2026
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94 changes: 92 additions & 2 deletions src/context-compactor.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,9 @@ function hasConsecutiveSameRole(turns: ConversationTurn[]): boolean {
describe("createPruningCompactor", () => {
test("returns turns unchanged when under the keep threshold", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 5,
summaryMaxChars: 500,
});
Expand All @@ -78,16 +81,28 @@ describe("createPruningCompactor", () => {
// compactorNoOpFloor accordingly breaks that guarantee silently.
const keepRecentTurns = 3;
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns,
summaryMaxChars: 500,
});
const floor = compactorNoOpFloor(keepRecentTurns);

// Bodies exceed the pinned tail budget, so past-floor always has a folded
// region while at-floor still no-ops on the count check alone.
const body = (i: number): string => `body ${i} ` + "x".repeat(100);
const atFloor = Array.from({ length: floor }, (_, i) =>
makeTurn({ role: i % 2 === 0 ? "user" : "assistant" }),
makeTurn({
role: i % 2 === 0 ? "user" : "assistant",
content: [{ type: "text", text: body(i) }],
}),
);
const pastFloor = Array.from({ length: floor + 1 }, (_, i) =>
makeTurn({ role: i % 2 === 0 ? "user" : "assistant" }),
makeTurn({
role: i % 2 === 0 ? "user" : "assistant",
content: [{ type: "text", text: body(i) }],
}),
);

expect(
Expand All @@ -100,6 +115,9 @@ describe("createPruningCompactor", () => {

test("compacts old turns and preserves recent ones", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
summaryMaxChars: 500,
});
Expand Down Expand Up @@ -150,6 +168,9 @@ describe("createPruningCompactor", () => {

test("preserves tool_call and tool_result blocks in recent turns", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
summaryMaxChars: 500,
});
Expand Down Expand Up @@ -183,6 +204,9 @@ describe("createPruningCompactor", () => {
describe("createPruningCompactor — initiating task preservation", () => {
test("keeps the initiating task verbatim even when it is far outside the recent window", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
maxAnchorTurns: 1,
summaryMaxChars: 500,
Expand Down Expand Up @@ -232,6 +256,9 @@ describe("createPruningCompactor — initiating task preservation", () => {

test("emits the compaction summary as a user turn, never system", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a one-token tail budget — only the mandatory floor stays
// live, so this tiny fixture still folds the same older region.
compactionShape: { tailBudgetTokens: 1 },
keepRecentTurns: 1,
summaryMaxChars: 500,
});
Expand All @@ -247,6 +274,9 @@ describe("createPruningCompactor — initiating task preservation", () => {

test("never emits consecutive same-role turns, even with adjacent user anchors", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a one-token tail budget — only the mandatory floor stays
// live, so this tiny fixture still folds the same older region.
compactionShape: { tailBudgetTokens: 1 },
keepRecentTurns: 2,
summaryMaxChars: 500,
});
Expand All @@ -270,6 +300,9 @@ describe("createPruningCompactor — initiating task preservation", () => {

test("keeps alternating roles when a tool_result user turn abuts a plain user turn", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
maxAnchorTurns: 3,
summaryMaxChars: 500,
Expand Down Expand Up @@ -338,6 +371,9 @@ describe("createPruningCompactor — image aging", () => {

test("strips image bytes from an anchored (aged) turn but keeps its text", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
maxAnchorTurns: 1,
summaryMaxChars: 500,
Expand Down Expand Up @@ -405,6 +441,9 @@ describe("createPruningCompactor — image aging", () => {

test("keeps an image intact when its turn is still within the recent window", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 3,
summaryMaxChars: 500,
});
Expand Down Expand Up @@ -437,6 +476,9 @@ describe("createPruningCompactor — image aging", () => {
// With few turns, full pruning is a no-op, but images outside keepRecentTurns
// must still spill so they are not resent as base64 forever.
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
summaryMaxChars: 500,
});
Expand Down Expand Up @@ -478,6 +520,9 @@ describe("createPruningCompactor — image aging", () => {

test("records the number of turns aged out in the transform record", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
maxAnchorTurns: 1,
summaryMaxChars: 500,
Expand Down Expand Up @@ -540,6 +585,9 @@ describe("createPruningCompactor — error anchoring (CL-6906)", () => {
...padding(8, "after"),
];
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 6,
maxAnchorTurns: 8,
summaryMaxChars: 2000,
Expand Down Expand Up @@ -587,6 +635,9 @@ describe("createPruningCompactor — error anchoring (CL-6906)", () => {
...padding(8, "after"),
];
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 6,
maxAnchorTurns: 8,
summaryMaxChars: 2000,
Expand Down Expand Up @@ -648,6 +699,9 @@ describe("createPruningCompactor — error anchoring (CL-6906)", () => {
...padding(8, "after"),
];
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 6,
maxAnchorTurns: 8,
summaryMaxChars: 2000,
Expand Down Expand Up @@ -734,6 +788,9 @@ describe("createPruningCompactor — maxAnchorTurns caps pairing pulls (CL-6906)

const maxAnchorTurns = 4;
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 6,
maxAnchorTurns,
summaryMaxChars: 2000,
Expand All @@ -755,6 +812,9 @@ describe("createPruningCompactor — summarize receives the workflow context (CL
let capturedCtx: unknown = "not called";
const workflowCtx = { workflow: { name: "build", stepIndex: 2, total: 7 } };
const compactor = createPruningCompactor({
// CL-9007: pin a one-token tail budget — only the mandatory floor stays
// live, so this tiny fixture still folds the same older region.
compactionShape: { tailBudgetTokens: 1 },
keepRecentTurns: 1,
summaryMaxChars: 500,
summaryContext: () => workflowCtx,
Expand All @@ -776,6 +836,9 @@ describe("createPruningCompactor — summarize receives the workflow context (CL
describe("createPruningCompactor — operator extra instructions", () => {
test("stores extra instructions on the compact record", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
summaryMaxChars: 500,
summaryContext: () => ({ extraInstructions: "keep the auth discussion" }),
Expand All @@ -799,6 +862,9 @@ describe("createPruningCompactor — operator extra instructions", () => {
makeTurn({ role: "user", content: [{ type: "text", text: "recent" }] }),
];
const written = await createPruningCompactor({
// CL-9007: pin a one-token tail budget — only the mandatory floor stays
// live, so this tiny fixture still folds the same older region.
compactionShape: { tailBudgetTokens: 1 },
keepRecentTurns: 1,
summaryMaxChars: 500,
summaryContext: () => ({ extraInstructions: "keep the auth discussion" }),
Expand All @@ -812,6 +878,9 @@ describe("createPruningCompactor — operator extra instructions", () => {

let captured: { extraInstructions?: string } | undefined;
const next = await createPruningCompactor({
// CL-9007: pin a one-token tail budget — only the mandatory floor stays
// live, so this tiny fixture still folds the same older region.
compactionShape: { tailBudgetTokens: 1 },
keepRecentTurns: 1,
summaryMaxChars: 500,
summaryContext: () => {
Expand Down Expand Up @@ -860,6 +929,9 @@ describe("createPruningCompactor — consolidated handoff (CL-7521)", () => {

test("second apply replaces the prior summary instead of accumulating", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
summaryMaxChars: 500,
});
Expand All @@ -880,6 +952,9 @@ describe("createPruningCompactor — consolidated handoff (CL-7521)", () => {

test("second apply keeps the initiating task as its own user turn", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
maxAnchorTurns: 1,
summaryMaxChars: 500,
Expand Down Expand Up @@ -941,6 +1016,9 @@ describe("createPruningCompactor — consolidated handoff (CL-7521)", () => {

test("harness spacer is stamped with the reserved producer id and a visible sentinel", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
summaryMaxChars: 500,
});
Expand Down Expand Up @@ -983,6 +1061,9 @@ describe("createPruningCompactor — consolidated handoff (CL-7521)", () => {

test("empty-fold keep-set returns the input unchanged", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
maxAnchorTurns: 8,
summaryMaxChars: 500,
Expand Down Expand Up @@ -1028,6 +1109,9 @@ describe("createPruningCompactor — consolidated handoff (CL-7521)", () => {
},
});
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 2,
summaryMaxChars: 500,
summarize,
Expand Down Expand Up @@ -1248,6 +1332,9 @@ describe("buildLLMTurnSummary", () => {
describe("buildTurnSummary via createPruningCompactor", () => {
test("summarizes tool_call and tool_result blocks in compacted turns", async () => {
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
summaryMaxChars: 2000,
});
Expand Down Expand Up @@ -1319,6 +1406,9 @@ describe("buildTurnSummary via createPruningCompactor", () => {
test("a truncated lying spine aborts instead of shipping", async () => {
const maxChars = 20;
const compactor = createPruningCompactor({
// CL-9007: pin a tiny tail budget so the fold covers the same older
// region the old keepRecentTurns cut folded.
compactionShape: { tailBudgetTokens: 10 },
keepRecentTurns: 1,
summaryMaxChars: maxChars,
});
Expand Down
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