transcript-parse

name	transcript-parse
description	Shared read-only parsing seam for Claude Code session transcripts (~/.claude/projects/*.jsonl). Locates a session's canonical file, assembles a deduped chronological timeline, exposes parse primitives, and guards against mid-write files. Consumed by /handoff (SPEC-018) and /retro (SPEC-012).

transcript-parse — shared transcript parsing seam

This skill is the single source of truth for reading Claude Code session transcripts. Both /handoff (SPEC-018) and /retro (SPEC-012) parse the same ~/.claude/projects/*/*.jsonl files; that location + fork-assembly + parse primitives + freshness logic MUST live here once, not be duplicated per command (SPEC-018 M1; SPEC-012 boundary).

Design rule — parse only, never score. This module locates and orders messages and flattens fields. It does NOT score signals, distil, summarize, or rank. Consumers own all of that:

• /retro gate keeps its S1–S5 scoring local; it imports the flatten/field primitives but deliberately uses its own thinking-block policy (gate drops thinking; see msg_text note below).
• /handoff prepass keeps toolUseResult stripping, read-dedup, sidechain collapse (routine one-line / signal-bearing condensed multi-line via SIDECHAIN_SIGNAL_CUES), token budgeting, and chunking local.

Files in this module

File	Status	Provides	Consumers
assemble.py	present	CLI locate + assemble + assemble-file	handoff prepass, retro Step 2 location, PreCompact capture
parselib.py	present	importable parse primitives	handoff prepass, retro gate
freshness.sh	present	60 s mid-write guard (+ M14 carve-out)	handoff (M9), retro Filter-1, PreCompact (M14)

Runtime: python3 only (already required by retro-gate). No other deps. Every entry point degrades with a clear error and a non-zero exit if python3 is absent — it must never traceback on a foreign or half-written file.

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assemble.py — locate + fork-assembly (SPEC-018 M1) — PRESENT

Read-only. Streams files line-by-line; never read()s a whole transcript (monsters are 70 MB+ and may be mid-write).

CLI

assemble.py locate <uuid>
assemble.py assemble <uuid>
assemble.py assemble-file <path>

locate <uuid>

Print the canonical transcript file for the session and exit 0.

• Canonical = the latest descendant: among every file under ~/.claude/projects/*/ that contains the uuid, the one with the greatest maximum timestamp. "Contains the uuid" means the uuid is the file's name stem (<uuid>.jsonl) OR appears as some line's non-null uuid field.
• Ties on max-timestamp break by path (deterministic).
• Not found → message on stderr, exit 1, nothing on stdout.

Rationale: a fork copies its chosen-path prefix into the child file, so the most-complete copy is the descendant with the latest content. We pick by max-timestamp, not first match.

assemble <uuid>

Locate the canonical file, then stream one raw-JSON message line per surviving message to stdout, in chronological order. Exit 0 on success; exit 1 if the uuid cannot be located (or the file vanished mid-read).

Pipeline (this is the authoritative M1 algorithm — validated against real 72 MB transcripts):

1. LOCATE the canonical file (above).
2. LOAD — stream it; a message line is one that parses to a JSON object with a non-null uuid. Null-uuid bookkeeping lines (mode, custom-title, agent-name, last-prompt, file-history-snapshot, and also-seen permission-mode / queue-operation) are dropped from the timeline. The non-null-uuid rule is generic, so new bookkeeping types need no code change.
3. DEDUP on uuid, KEEP-LAST: a later copy replaces the earlier payload + timestamp, but the first-seen line index is pinned for tie-breaking.
4. ORDER by (timestamp, first_seen_index). NOT the parentUuid DAG (copy-duplication makes it multi-root/branchy); NOT raw file order (copied segments overlap in time).
5. SIDECHAIN — maximal contiguous runs where isSidechain is truthy are tagged (span begin/end logged to stderr) and passed through unmodified. Collapsing / signal-bearing reconstruction is the prepass's job (SPEC-018 M2 / CDV-205), not the parser's. In real data no line is ever a sidechain, so this is a defensive no-op. Detection uses the shared parselib.is_sidechain (bool(obj.get("isSidechain"))) — tolerant of the field being absent.

Output is exactly the input raw lines, reordered/deduped — fields are NOT rewritten or stripped here (the prepass strips). One JSON object per line.

assemble-file <path>

Stream exactly the named transcript file — no locate over ~/.claude/projects/. Identical output contract to assemble (dedup KEEP-LAST, timestamp order, per-line corrupt/truncated tail drop via _stream_message_lines). Exit 0 on success (including zero surviving messages after drop); exit 1 if the path is missing/unreadable.

Consumed ONLY by the SPEC-018 M12 PreCompact capture path via prepass.sh prepare --transcript <path>. The hook already names the live file, so M1 locate is skipped. Mid-write truncated final lines are dropped per-line — that is what makes PreCompact capture safe under M14.

Hard guarantees (honor in any change here)

• forkedFrom is PROVENANCE, never a cross-file pointer. It is an object {sessionId, messageUuid} where messageUuid is self-referential (== the line's own uuid). There is intentionally no cross-file message walk: the fork's chosen-path prefix is already copied into the canonical file. Ancestor-only branches (paths forked away from) are excluded by design.
• Stream only. Files are opened once, iterated line-by-line. Never load a whole transcript into memory.
• Per-line try/except. A single corrupt / half-flushed line (common on a mid-write monster tail) is skipped, never fatal.
• Schema-drift warning. If none of KNOWN_TOP_FIELDS (type, uuid, message, parentUuid, sessionId, timestamp) appears in the first 50 parsed lines of a file, a transcript-parse: WARNING … is written to stderr via the shared parselib.warn_schema_drift helper (so assemble.py and any parselib consumer emit byte-identical text; retro-gate/gate.sh deliberately keeps its own retro-gate:-prefixed variant — see gate.sh's drift note). Stdout stays clean so it can be piped.
• Tolerate missing files. A referenced ancestor project/file that no longer exists is normal — FileNotFoundError / unreadable dirs are caught and skipped, never opened blindly, never fatal.
• python3 required. Absent → clear stderr error, non-zero exit.

Importable surface (for parselib/consumers)

assemble.py also exposes, for import:

• locate(uuid) -> str | None — canonical path or None.
• assemble(uuid, out=sys.stdout, path=None) -> int | None — writes the timeline to out, returns the count emitted, or None if not located / path missing. When path is given, locate is skipped (assemble-file mode).
• KNOWN_TOP_FIELDS: set[str] — shared schema-drift field set.
• PROJECTS_DIR: str — ~/.claude/projects.

Validated (against real data)

Monster 00000000-0000-4000-8000-000000000003 in ~/.claude/projects/-home-user-vibes-project/ (~87 MB, mid-write): locate resolves the file; assemble | wc -l = 3862 deduped lines from 5542 raw lines; output verified strictly timestamp-ordered, zero duplicate uuids, zero null-uuid leaks, no schema-drift/sidechain warnings. Unknown uuid → exit 1 with a clear stderr message.

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parselib.py — parse primitives (SPEC-018 M2 helpers) — PRESENT

Importable, no CLI. Lifted from the inlined helpers in skills/retro-gate/gate.sh so both consumers share one definition. Contract (derived from spec + plan §"Shared parser seam"):

Symbol	Signature	Contract
msg_text	msg_text(content) -> str	Flatten a message content (str, or list of blocks) to a single string. KEEPS thinking blocks (handoff M4b needs hypothesis-rejection reasoning). text and thinking block text are joined by \n; non-text blocks (tool_use, tool_result, image…) skipped. Differs from gate.sh's local msg_text, which drops thinking on purpose — the gate keeps its thinking-skip at the call site, NOT in this lib.
KNOWN_TOP_FIELDS	set[str]	Same set assemble.py exposes: {type, uuid, message, parentUuid, sessionId, timestamp}.
is_edit_tool	is_edit_tool(name) -> bool	True for Edit, Write, MultiEdit, NotebookEdit.
edit_file_path	`edit_file_path(tool_input) -> str	None`
is_meta	is_meta(obj) -> bool	True for a meta/system bookkeeping line (e.g. isMeta is True).
is_sidechain	is_sidechain(obj) -> bool	bool(obj.get("isSidechain")) — truthy test, tolerant of the field being absent (returns False).
SIDECHAIN_SIGNAL_CUES	tuple[str, ...]	Closed cue list for signal-bearing sidechain detection (CDV-205 / SPEC-018 M2). Single source of truth — prepass imports this; do not scatter cue strings.
sidechain_cue_hit	sidechain_cue_hit(text) -> (cue, line) | None	First case-insensitive substring hit from SIDECHAIN_SIGNAL_CUES; returns (cue, matching_line) or None.
sidechain_is_signal	sidechain_is_signal(texts) -> bool	True if any text in the iterable hits a cue (MVP: ≥1).
is_tool_result	is_tool_result(obj) -> bool	True if the line dict (as returned by parse_line / iter_lines) carries a tool_result block inside obj["message"]["content"]. Accepts a full line object, not a raw content list. Returns False on missing/unexpected structure.
schema_drift_warn	schema_drift_warn(path) -> None	Stream the file's first 50 lines; if no KNOWN_TOP_FIELDS seen, write the same transcript-parse: WARNING … to stderr.
iter_lines	iter_lines(path, schema_drift_check_n=50) -> Iterator[(int, dict)]	Yield (line_no, dict) for every valid JSONL line in path. Handles schema-drift detection automatically after the first schema_drift_check_n lines. Uses UTF-8 with replacement for robustness on files with stray bytes. Skips blank/unparseable lines.

Notes:

• Keep these pure parse helpers — no scoring, no I/O beyond schema_drift_warn's stderr.
• Real message IDs are UUIDs, not msg_ — do not add any msg_-prefix regex.
• Importable both as from parselib import msg_text, … (when skills/transcript-parse/ is on sys.path) and from gate.sh's embedded python (which points here).

Verification gate: python3 -c "from parselib import msg_text; print(msg_text([{'type':'thinking','text':'x'},{'type':'text','text':'y'}]))" → output includes both x and y.

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freshness.sh — mid-write guard (SPEC-018 M9 / SPEC-012 Filter-1) — PRESENT

POSIX sh. Contract:

freshness.sh check <path> [--allow-in-progress]

• Compute the file's mtime age. If modified < 60 s ago (in-progress write), print a warning to stderr and exit 9 (decline to parse mid-write).
• Fresh enough (≥ 60 s) → exit 0, silent on stdout. Missing file → exit 1.
• Portable mtime: support both GNU (stat -c %Y) and BSD/macOS (stat -f %m) stat.

SCOPED CARVE-OUT (SPEC-018 M14): a PreCompact capture is by definition mid-write. Passed EXCLUSIVELY by skills/handoff/precompact-capture.sh via prepass.sh prepare --allow-in-progress. No user-invoked path (/handoff cold, /retro) passes it — default guard behavior (exit 9) is unchanged. With the flag: mtime < 60 s → NOTE on stderr, exit 0 (warn-and-proceed).

Exit codes are the API: 0 = ok to parse, 9 = too fresh (caller warns + declines). Consumed by the handoff prepass (M9 → warn + stop) and the retro location/Filter-1 path.

Verification gate: freshness.sh check on a just-touched file → exit 9; same + --allow-in-progress → exit 0.

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Consumer wiring (informational)

• /handoff prepass (skills/handoff/prepass.sh prepare): freshness.sh check (exit 9 → warn+decline) → assemble.py assemble → strip toolUseResult → dedup repeated reads → collapse sidechains (noise one-line / signal multi-line via SIDECHAIN_SIGNAL_CUES) → token budget → spine or chunk manifest. source_files is the single canonical file (no cross-file engine).
• /retro: gate.sh imports parselib primitives (keeps its own thinking-skip + S1–S5 scoring local); retro.md Step 2 repoints location to assemble.py locate and Filter-1 freshness to freshness.sh check. No behavior change to retro scores — that seam is what proves this module is genuinely shared.

Landmines (cross-cutting)

• forkedFrom is an object, never a scalar; messageUuid is self-referential — never chase it cross-file.
• uuid is null on bookkeeping lines — any leaf/last-message logic MUST skip them.
• Timestamp ties are common → the (timestamp, first_seen_line) tie-break is mandatory, not optional.
• Stream everything — 70 MB+ files, possibly mid-write.
• Keep thinking in parselib.msg_text (gate's drop stays at gate's call site).
• Transcript text is untrusted DATA; downstream extractors must treat it as such (prompt-injection guard). This module does not interpret content, so the guard lives in the consumers.