id: design: session header + segment checkpoint event kind

Design the durable encoding for checkpointed live sessions — the input everything else in the #2034 family depends on.

Why

#2034 investigation (doc: doc/2026-10-29T10-45-00Z_investigation_ephemeral_live_data_retention/) concluded on a two-tier model: durable facts stay on the per-author signed hash chain (ChainExt), keystroke/cursor/input traffic moves to an ephemeral per-session stream authenticated by a session header + per-session MAC key, closed by intermittent segment checkpoints. Nothing in the tree defines what a session header or a checkpoint is.

Scope

Define SessionHeader and SegmentCheckpoint records and a new ChainExt.kind (session.checkpoint), with canonical-CBOR encoding and golden test vectors, verified the same way as any other signed event (pkgs/id/src/chain.rs:282-342).
Decide the open question from the investigation: is a checkpoint an ordinary graph event, or a parallel signed artifact in the artifact.rs shape referenced from the graph? State the trade-off and pick one.
Decide the session-header MAC key scheme: committed in the header vs derived per session from a long-term key; behaviour on key rotation mid-session.
Specify segment policy defaults (N events / T seconds, plus emission on commit/blur/disconnect) and whether it is world-configurable like WorldLimits (pkgs/id/src/world/mod.rs:59-99).
Specify how checkpoints interact with fork proofs and the waiting pool (pkgs/id/src/event_store/mod.rs:12-22, waiting.rs) so a later compaction cannot break after resolution.
Peer countersignature (peer_signature) variant: which classes must require it (id: investigate: match-result attestation — mutual concession, witness adjudication, offline play #2037/id: investigate: match audit — netcode log format, replay validation, and cheating signals #2038 consume this).

Acceptance

A design doc under doc/ linked from this issue with the record shapes, encoding, verifier walk, and the decisions above.
Wire fields and a verifier algorithm concrete enough that the PoC issue can be built from it without further design.
No permanent feature built here — this is design only.

Refs #2034, #2056.

CODE-1108

🤖 Agent note · picked up

Agent: repo queue worker, lane D (repo-queue-worker-shift-d)
Session / ID: queue task 3461 (triage, fleet-monitor safety-net), claimed 2026-11-01T08:05Z
Task: Triage id: design: session header + segment checkpoint event kind #2240: re-verify the design claims against current main, decide the design route and any gating follow-ups.
Expectation: claim-by-claim verdict posted on this issue this shift; the design production routed as one follow-up packet with the PoC explicitly gated behind it.

🤖 Agent note · triaged — CONFIRMED; design production routed as one packet (task 5240), PoC explicitly gated

Agent: repo queue worker, lane D (repo-queue-worker-shift-d)
Session / ID: queue task 3461 (triage, fleet-monitor safety-net), claimed 2026-11-01T08:05Z
Claims re-verified against main d85e4098cf113ec7c3add1a74c0c03fd9840d429 (gh api contents + code search, 2026-11-01):
- ✅ The id: investigate: ephemeral live data vs the chained event graph — retention and intermittent signing #2034 investigation doc exists (doc/2026-10-29T10-45-00Z_investigation_ephemeral_live_data_retention/); its §5 sketches SessionHeader / SegmentCheckpoint / LiveFrame and leans graph-event, but its §9 explicitly leaves the deciding questions open "for the synthesis issue" — that synthesis is this issue. The design work is real and un-done.
- ✅ Nothing in the tree defines these records: code search for SegmentCheckpoint and session.checkpoint matches only the investigation doc — no definition in pkgs/id or anywhere else.
- ✅ The extension pattern the design must use exists: pkgs/id/src/chain.rs — ChainExt carries a free-form kind: String with kind-specific payload validation (tag/document/removal kinds) in validate(), and sign() at :282 as cited.
- ✅ WorldLimits confirmed at pkgs/id/src/world/mod.rs:59-99; event_store/mod.rs describes the forks/waiting tables as cited; pkgs/id/src/artifact.rs exists (the parallel-artifact alternative is a real in-tree shape).
- ⚠️ One stale citation: the waiting pool is event_store/waiting_rows.rs on current main — there is no waiting.rs. Filename only; the substance is unchanged.
- Family state: id: investigate: ephemeral live data vs the chained event graph — retention and intermittent signing #2034 closed, id: investigate: match-result attestation — mutual concession, witness adjudication, offline play #2037 closed, id: investigate: match audit — netcode log format, replay validation, and cheating signals #2038 closed (investigations whose conclusions consume the peer_signature decision), epic: ID platform expansion — apps, comms, currency, hosting, boards (2026-10-28 directive, LIST 6–15) #2056 open (epic; its program rule bars building the PoC into the permanent feature before a review round).
Design route DECIDED: one follow-up packet produces the design doc (investigation follow-on 1 — this issue's own deliverable). The packet pins that the doc must decide, with trade-offs stated, all five questions the issue scopes: (1) graph event vs parallel artifact.rs-shape artifact; (2) MAC key committed vs derived, plus mid-session rotation behaviour (§6's "rotation = new session header" settled or replaced); (3) segment policy defaults (N events / T seconds, emission on commit/blur/disconnect) and WorldLimits-configurability; (4) fork-proof / waiting-pool interaction so compaction cannot break after resolution; (5) the peer_signature required-classes table for id: investigate: match-result attestation — mutual concession, witness adjudication, offline play #2037/id: investigate: match audit — netcode log format, replay validation, and cheating signals #2038. Encoding + golden vectors are required as spec; no code, per the issue's own acceptance.
Gate recorded: the PoC (follow-on 2) is not enqueued and must not start until this design lands and gets its review round (epic: ID platform expansion — apps, comms, currency, hosting, boards (2026-10-28 directive, LIST 6–15) #2056 program rule). Downstream follow-ons 3–6 route only after that.
Routing: packet packets/task3461-2240-session-checkpoint-design.json, enqueued as queue task 5240. This issue stays open until the design doc lands.

🤖 Agent note · parked

Agent: queue worker (repo-worker-code), OpenChamber scheduled lane
Session / ID: task 5240
Found via: queue claim · verified fresh GitHub state
Task: Parked because issue id: design: session header + segment checkpoint event kind #2240 is assigned to dezren39 and canonical PR design(id): #2240 session checkpoint encoding #3867 remains OPEN, non-draft, authored and assigned to dezren39; no PR contents, branch, or saved worktree were inspected.
Expectation: effort/xs; resume only after explicit Drew release/handoff or PR design(id): #2240 session checkpoint encoding #3867 reaches a disposition, then revalidate metadata before acting.
Links: issue id: design: session header + segment checkpoint event kind #2240 · PR design(id): #2240 session checkpoint encoding #3867 · worktree reference /home/user/git/fleet/5240 (untouched)

🤖 Agent note · picked up for metadata-only ownership revalidation

Agent: queue worker (repo-worker-code), OpenChamber scheduled lane
Session / ID: OpenCode session ses_e5e6382f632ffeoXT3muAxJr0w · queue task 5240
Found via: atomic queue claim; resumed from parked ownership checkpoint
Fresh metadata: id: design: session header + segment checkpoint event kind #2240 OPEN and assigned to dezren39; sole matching PR design(id): #2240 session checkpoint encoding #3867 OPEN, non-draft, authored and assigned to dezren39.
Action: no PR content/checks, branch, or worktree inspected or touched.
Next: park pending PR disposition or explicit ownership release.

🤖 Agent note · parked — Drew-owned PR remains open

Agent: queue worker (repo-worker-code), OpenChamber scheduled lane
Session / ID: OpenCode session ses_e5e6382f632ffeoXT3muAxJr0w · queue task 5240
Evidence: id: design: session header + segment checkpoint event kind #2240 is OPEN and assigned to dezren39; sole matching PR design(id): #2240 session checkpoint encoding #3867 is OPEN, non-draft, authored/assigned to dezren39 on design/id-2240.
Disposition: parked until 2026-11-02T14:23:13Z. No PR contents/checks, branch, or saved worktree inspected or touched. Existing labels reflect parked state: work/assigned, queue/parked, status/parked.
Resume condition: explicit Drew release/handoff or PR design(id): #2240 session checkpoint encoding #3867 disposition; then revalidate before resuming.

🤖 Agent note · picked up

Agent: queue worker (repo-worker-code), lane B shift
Session / ID: task 5240 (resume)
Found via: queue claim
Task: Resuming task 5240 for issue id: design: session header + segment checkpoint event kind #2240: fresh check shows no held / user/owned / do-not-merge / do-not-auto-edit labels on issue id: design: session header + segment checkpoint event kind #2240 or PR design(id): #2240 session checkpoint encoding #3867, so the earlier "Drew-owned" park (authorship/assignee based) does not hold — hard stops are labels. I have reviewed PR design(id): #2240 session checkpoint encoding #3867's design doc against the packet's five pinned decisions, record shapes, verifier walk, and encoding spec; requesting Codex re-review on the current head, then merging if clean.
Expectation: effort/s — done when PR design(id): #2240 session checkpoint encoding #3867 is merged and linked from issue id: design: session header + segment checkpoint event kind #2240 (the PoC stays gated on the epic: ID platform expansion — apps, comms, currency, hosting, boards (2026-10-28 directive, LIST 6–15) #2056 review round; issue id: design: session header + segment checkpoint event kind #2240's design deliverable completes, implementation follow-ons are separate).
Links: PR design(id): #2240 session checkpoint encoding #3867, branch design/id-2240

docs: define keyless vs MAC-authenticated verification for #2240 segm…

design(id): #2240 session checkpoint encoding (#3867)

🤖 Agent note · done

Agent: queue worker (repo-worker-code), lane B shift
Session / ID: task 5240
Found via: queue claim (resume)
Task: Design deliverable for issue id: design: session header + segment checkpoint event kind #2240 landed — PR design(id): #2240 session checkpoint encoding #3867 squash-merged as 2dcbb4ee, adding doc/2026-11-01_design_id2240.md.
Expectation: done — issue id: design: session header + segment checkpoint event kind #2240 closes with this note; the id: PoC: intermittent-signature live stream for collaborative editing #2241 PoC remains gated on the epic: ID platform expansion — apps, comms, currency, hosting, boards (2026-10-28 directive, LIST 6–15) #2056 review round and is NOT started by this task.
Links: PR design(id): #2240 session checkpoint encoding #3867 (merged, final head 047786e1e), design doc doc/2026-11-01_design_id2240.md
Review record: the doc decides all five pinned questions with trade-offs (graph events over a parallel artifact chain; fresh per-session MAC key with a signed commitment and rotation-by-new-session; 256-frame/2-second boundaries with WorldLimits ceilings pinned in the signed header; fork/waiting/compaction via protected prune_behind_cut roots; the peer_signature required-classes table), gives concrete SessionHeader/SegmentCheckpoint wire shapes, the exact MAC/root formulas, and an 8-step verifier walk. Golden vectors are specified as a freeze-list with the exact hash formulas (implementation step 1 of the doc's phased plan produces the literal vectors with the typed schema). Codex review: clean on the original head, one P2 on re-review (no keyless verification path for retained segment bodies) — fixed in 047786e1e by splitting keyless root/replay verification from MAC-authenticated verification plus a post-close key-disclosure path, replied on the thread, re-review clean. Earlier "Drew-owned" parks on task 5240 were the known authorship misread: no held/user/owned/do-not-* labels exist on issue id: design: session header + segment checkpoint event kind #2240 or PR design(id): #2240 session checkpoint encoding #3867.

Navigation Menu

Repository navigation

id: design: session header + segment checkpoint event kind #2240

Why

Scope

Acceptance

82 remaining items

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

id: design: session header + segment checkpoint event kind #2240

Description

Why

Scope

Acceptance

Activity

developing-today commented on Oct 29, 2026

dezren39 commented on Nov 1, 2026

dezren39 commented on Nov 1, 2026

82 remaining items

dezren39 commented on Nov 2, 2026

dezren39 commented on Nov 2, 2026

dezren39 commented on Nov 2, 2026

dezren39 commented on Nov 2, 2026

dezren39 commented on Nov 2, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions