feat(session): default JSONL writes to packed rows

This commit is contained in:
Tianyi Cui
2026-07-26 23:44:52 +08:00
parent cad2af4741
commit 4ff496c65c
47 changed files with 521 additions and 251 deletions
@@ -15,7 +15,7 @@ The JSONL durable session-persistence backend — a concrete `SessionPersistence
```
- The first logical line is the immutable `SessionHeader` tagged `{ type: 'session', version, id, cwd?, createdAt, parentSession?, seedLength?, delegationDepth }`. `delegationDepth` is required on disk and is `0` for a top-level session; a missing or invalid value rejects the log. Every subsequent logical line is one storage record; `assistant/chunk` events are never dropped, and `seq` stays contiguous across the decoded log (`events[i].seq === i`).
- A storage record is a `SessionEvent` JSON verbatim, or — written only under `packChunks` — a **packed chunk row** (`text-chunks` / `reasoning-chunks` / `tool-call-chunks`; bare slash-less tags like the header's `session`, so row tags cannot be confused with event types): one line holding a run of ≥3 consecutive same-block `assistant/chunk` delta events, `seq0`/`time0` plus per-member `dt` gaps reconstructing every member's `seq`/`time` exactly. The lossless codec lives in `@deepseek-ai/dsh-session` (`packChunkRuns`/`decodeStorageRecord`) and whitelists exact shapes — anything unrecognized stores verbatim. Reading is layout-blind: `load` always decodes rows, so packed, unpacked, and mixed files load identically.
- A storage record is a `SessionEvent` JSON verbatim, or — for an eligible run when `packChunks` is enabled — a **packed chunk row** (`text-chunks` / `reasoning-chunks` / `tool-call-chunks`; bare slash-less tags like the header's `session`, so row tags cannot be confused with event types): one line holding a run of ≥3 consecutive same-block `assistant/chunk` delta events, `seq0`/`time0` plus per-member `dt` gaps reconstructing every member's `seq`/`time` exactly. The lossless codec lives in `@deepseek-ai/dsh-session` (`packChunkRuns`/`decodeStorageRecord`) and whitelists exact shapes — anything unrecognized stores verbatim. Reading is layout-blind: `load` always decodes rows, so packed, unpacked, and mixed files load identically.
- The project directory keeps the normalized cwd readable for navigation and is bounded for filesystem component limits. Separator replacement and truncation are intentionally lossy, so cwd strings that normalize alike share a project directory; session ids still select distinct session directories. On a case-insensitive filesystem, identity validation accepts an alternate path spelling only when filesystem canonicalization resolves both spellings to the same transcript. The configured root remains deployment-controlled: it may be project-local, shared, temporary, or centralized. The [project-session directory decision](../../../.agents/notes/implemented/architecture/2026-07-24-project-session-directories.md) records this tradeoff.
- Session ids are unvalidated branded strings, so they are injectively escaped to a single safe path segment before use (no traversal, no collision). The resulting directory is reserved for additional session-owned artifacts; discovery reads only the fixed transcript filename.
@@ -24,7 +24,7 @@ The JSONL durable session-persistence backend — a concrete `SessionPersistence
| Key | Type | Notes |
|---|---|---|
| `root` | `string` (required) | Root directory for all session files. **No default** — a `process.cwd()` default would scatter files as the process's cwd changes (bash calls, subprocesses). An existing root must be a readable directory; an absent root is created on first materialization. |
| `packChunks` | `boolean` (default `false`) | Write delta-chunk runs as packed rows (~60% smaller logical logs measured on a real coding session). Off, the written logical layout is byte-identical to the pre-packing format; reading packed rows works regardless of this switch. Off by default while the snapshot goldens stay one-event-per-line — recording with packing on rewrites every fixture `session.jsonl`. |
| `packChunks` | `boolean` (default `true`) | Write eligible delta-chunk runs as packed rows (~60% smaller logical logs measured on a real coding session). Set `false` for one-event-per-line diagnostics; reading packed rows works regardless of this write-side switch. |
| `compression` | `'zstd' \| 'none'` | Defaults to `'zstd'`; `'none'` retains newline-delimited UTF-8 text. |
`locate(meta)` returns `{ kind: 'jsonl', path }` for the fixed transcript inside the resolved project/session directories. It performs no filesystem I/O: the target can be returned before the directory or file exists, and an existing file contains only the last flushed prefix.