Tianyi Cui
e6fad266a6
Define the in-file RFC contract in docs/rfc/README.md § The file format: the header block (`# RFC: <title>` plus a dateless Status enum cross-checked against the lifecycle folder), the per-lifecycle body skeleton (a Problem opener everywhere; Proposal/Alternatives considered/ Acceptance criteria/Risks in proposed/; present-tense Decision/ Consequences with proposal-era headings banned in implemented/; the frozen proposal shape in rejected/), and a mandatory Alternatives considered section with a date-fenced grandfather comment for pre-format RFCs whose alternatives are not reconstructible from the record. Enforce it with a new doc-sync gate, scripts/verify-rfc-format.ts, and normalize all 112 RFCs to it: ~15 Status-line spellings collapse to the enum, 29 Context openers become Problem, the 39 legacy-format XXX debt markers are resolved and banned from reappearing, proposal-era sections in implemented RFCs are rewritten to shipped reality (including the web/fs/subagent seam RFCs' migration plans and test checklists, closing the doc-tiers deferred-work item on the web seam), every RFC gains an Alternatives considered section or the grandfather comment, and the bilingual pair is re-mirrored and re-recorded. Move the generated index tables out of README.md into a fully generated docs/rfc/INDEX.md — gen-rfc-index now writes the whole file, and verify-rfc-classification checks its freshness and rejects index-shaped rows in the curated README — which makes room for the format contract to live in the README front door instead of a separate FORMAT.md. The decision record, and the first RFC written in the new format, is docs/rfc/implemented/process/2026-07-05-uniform-rfc-format.md.
27 lines
1.8 KiB
Markdown
27 lines
1.8 KiB
Markdown
# RFC: Event-sourced sessions with derived message history
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Status: implemented
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## Problem
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The MVP requires strict event-based tracing with fully replayable sessions (严格的基于事件的trace、logging系统，session完全可回放).
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## Decision
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A `Session` is an append-only log of typed `SessionEvent`s — the single source of truth. The LLM message history is *derived* from the log (`deriveMessages()`); raw stream chunks are logged for token-level replay fidelity while the assembled `assistant/message` event is authoritative for derivation. Replay/fork = seed a new session with an existing log.
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Appends are synchronous (the hot path never blocks on I/O); `session/event` is a sync notification; persistence plugins buffer write-behind and drain at the awaited `session/flush` checkpoint fired at every turn end.
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Ordering contract: the loop appends to the session *before* emitting the corresponding Cordis event, and the `agent/step-result` waterfall runs before the `assistant/message` append so the log records what tool dispatch actually used (post-review fix; regression-tested).
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## Alternatives considered
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**A mutable message array with events fired as notifications** — simpler, but state and log can diverge; with event-sourcing the log IS the state, so divergence is structurally impossible.
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## Consequences
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- Replay, trace, and telemetry are structurally guaranteed, not bolted on.
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- Persistence stays a plugin concern; the in-memory store ships in dsh-session.
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- The event vocabulary is merge-extensible (plugins add e.g. compaction events); [session persistence](2026-06-14-session-persistence.md) froze its shape once the log became durable.
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- Derivation cost grows with log length — compaction (future plugin) is the intended mitigation, not log mutation.
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