return coalesceClaudeCliToolMessages(messages);

}

// Compaction surface in Claude Code's JSONL: `/compact` writes a

// `type: "summary"` entry whose `summary` field holds the condensed text,

// and an associated `type: "system", subtype: "compact_boundary"` entry

// whose `compactMetadata` carries `trigger`/`preTokens`. After a boundary,

// only post-compaction `user`/`assistant` turns are written as individual

// entries; pre-compaction context lives in the summary. This shape mirrors

// what Claude Code itself sends to the model after compaction (summary plus

// recent turns), per the upstream session-management docs.

type ClaudeCliCompactBoundaryEntry = {

type: "system";

subtype?: unknown;

};

export type ClaudeCliFallbackSeed = {

/**

* The most recent compaction summary, if the session has been `/compact`-ed

* at any point. Sourced from the latest `type: "summary"` entry, falling

* back to the latest `compact_boundary` content when no explicit summary

* is present (older Claude Code builds).

*/

summaryText?: string;

/**

* User/assistant turns after the most recent compact boundary, or all

* turns when the session has never been compacted. Tool-result turns are

* coalesced into adjacent assistant turns the same way

* `readClaudeCliSessionMessages` does, so consumers can format them like

* a regular transcript.

*/

recentTurns: TranscriptLikeMessage[];

};

}

function extractCompactBoundaryFallbackText(entry: ClaudeCliProjectEntry): string | undefined {

// When `/compact` is invoked, Claude Code writes a separate summary entry

// — but on older builds the boundary's `content` ("Conversation compacted")

// is the only signal that compaction happened. Prefer the explicit summary

// when both exist; this fallback gives a non-empty hint when only the

// boundary is present so the seed at least labels the gap honestly.

const content = (entry as ClaudeCliCompactBoundaryEntry).content;

return typeof content === "string" && content.trim() ? content.trim() : undefined;

}

return undefined;

}

// Pair each compact_boundary with the summary entry that preceded it

// since the previous boundary, so a later compaction whose summary is

// missing (e.g. crash mid-write) does not silently keep an older

// compaction's summary alive (#72069 Codex P2). Walk shape:

// - explicit `summary` entry queues into `pendingSummary` until the

// next boundary "consumes" it.

// - `compact_boundary` flushes the pending summary into `lastSummary`,

// refreshes `lastBoundaryFallback` from the boundary's content, and

// drops the windowed turns and tool registry.

// - everything after the latest boundary forms the recent-window the

// fallback runner will replay alongside the summary.

let pendingSummary: string | undefined;

let lastSummary: string | undefined;

let lastBoundaryFallback: string | undefined;

const explicitSummary = extractSummaryText(parsed);

if (explicitSummary) {

// Queue the summary; the next boundary will pair it with itself.

// Multiple summaries between boundaries (rare) take the last one,

// matching how Claude Code's resume picks the most recent summary.

pendingSummary = explicitSummary;

continue;

}

if (isCompactBoundary(parsed)) {

lastSummary = pendingSummary; // may be undefined if no preceding summary

lastSummary = pendingSummary;

pendingSummary = undefined;

lastBoundaryFallback = extractCompactBoundaryFallbackText(parsed) ?? lastBoundaryFallback;

// Drop turns that lived before this boundary — they are now

// represented by the summary, and replaying them would double-count

// their tokens against the fallback model's budget.

windowedTurns = [];

// Reset tool-name registry too: tool ids before a compact boundary

// are no longer visible to the post-boundary turns.

toolNameRegistry.clear();

continue;

}

}

const recentTurns = coalesceClaudeCliToolMessages(windowedTurns);

// Honor a `/compact` summary that was written but never followed by a

// boundary marker (older Claude Code build, or graceful-degrade case).

// `pendingSummary` then carries the latest such summary into the result.

const resolvedSummaryText = lastSummary ?? pendingSummary ?? lastBoundaryFallback;

if (!resolvedSummaryText && recentTurns.length === 0) {

return undefined;