A cancel/dispose landing inside the first agent/session-prefix waterfall
used to commit the listener chain's return value to the instance cache
before the interruption check dropped the turn; an abort-aware listener's
degraded fallback would then ship on every later request of the instance.
The commit now happens only after the composition survives the
interruption check — the cache only ever holds a fully composed prefix,
and the next turn recomposes under a live signal.
ds-review-bot critical (follow-up): on the first step of a resumed or
seeded/forked instance, auto-compaction ran before runStep composed
this instance's prefix, so the gate read the PREVIOUS instance's logged
prefix from the header fold — a contributor that grew across
resume/fork (skills added, AGENTS.md grown: exactly the
environment-dependent case) could under-gate and ship an over-window
first request.
The loop now composes agent/session-prefix before the instance's first
agent/pre-step (still once per instance; runStep just reads the cache),
and agent/pre-step carries the composed prefix to its listeners.
CompactService.compactIfNeeded gains the sessionPrefix parameter;
BasicCompactService.estimatePressure gates on the handed value — the
header-fold read is gone, so the estimate is exact at every step
including a resumed/forked instance's first. Composition moving before
the boundary snapshot also means a composing listener's session append
now joins the CURRENT request (documented on the seam).
New coverage: composition precedes pre-step and the seam receives the
composed prefix; cancel and disposal landing inside the composition
window drop the step cleanly; the compact gate test hands the prefix
directly.
Two ds-review-bot findings:
The seam JSDoc claimed extending 'await next()' composes in
registration order — false for the append form: the waterfall unwinds
innermost-first, so appending places later-registered contributions
first. The canonical contribution is now documented as the PREPEND
'[mine, ...await next()]' (registration order on the wire), with the
append form's reverse-order behavior stated explicitly; the ordering
test now uses the canonical pattern in both listeners.
scrubRequestHeaders tokenized only system/tools, so a fixture recording
a composed session prefix would carry its raw text (workspace-specific
churn/leak). The scrubber now maps each header/delta messagePrefix
entry to a {{messagePrefix}} token — count stays a structural fact,
absence stays absent, the empty-array transition stays visible — with
normalize.spec coverage for the header, delta, absence, and odd-shape
paths.
Review discussion converged on the industry shape (Claude Code caches
user context per conversation; Codex separates initial context from
diffs; Kimi appends at continuation boundaries to protect prompt
caching): stable openers belong in a compose-once prefix, mid-session
changes belong in append-only history — not in a per-request slot.
agent/session-prefix fires ONCE per loop instance, lazily on its first
request-building step: the composed Message[] is deep-frozen, cached on
the transmission bookkeeping, recorded as EpochHeader.messagePrefix on
the anchoring 'initial'/'resume' snapshot, and reused verbatim for
every request the instance sends — prefix stability is structural, not
a producer discipline, and a resume recomposes with attributable drift.
The request is messagePrefix + boundary snapshot.
The per-step RequestAdvice/RequestAdviceContext surface and the
messageSuffix header field are dropped: the tail slot had no consumer,
and every current update pattern (new AGENTS.md discovered, memory
update, skills change) routes through the existing append-only history
channels — inject(), tools/post-execute additionalContext,
prompt-submit additionalContext — each paid once and prefix-cached
thereafter. The messagePrefix delta arm stays for codec totality; the
loop never produces one in practice.
tianyicui's review: the seam name did not say what the event or its
types do. 'advice' reads both ways — advisory content for the model,
and AOP before/after advice woven around a join point (here the
derived history) without modifying it — so RequestAdvice.before/after
are self-describing. Types follow: RequestAdvice / RequestAdviceContext;
the logged EpochHeader fields keep their positional names
(messagePrefix/messageSuffix).
Also sharpens the core.md wording the review flagged as ambiguous:
before-advice sits in front of the ENTIRE derived history, directly
after the system slot (the conventional home for session-stable openers
— an AGENTS.md digest, a skills catalog), after-advice follows the
history's last message. Catalogs and doc graphs regenerated.
Review follow-up (#196): a listed name with no registered tool was silently
ignored; misconfiguration must block work instead. The check lives in the
assembly — the earliest moment the registered tool set exists (tool plugins
register after the service constructs) and the only universal one (cordis has
no "all plugins loaded" event; registrations change at any time). assemble()
is now async so the throw surfaces as a rejection rather than a synchronous
escape from a Promise-returning method.
Blast radius, pinned by a loop-level test: the rejection reaches the turn's
outer catch — the turn closes balanced with an `error` reason, agent/error
mirrors it, no step opens, no request/header is logged, no request reaches
the adapter, and the agent returns to idle; every turn fails identically
until the config is fixed. A boot-time validation pass was considered and
rejected (recorded in the RFC). The general principle — misconfiguration
fails loud, never a silent skip — is added to AGENTS.md.
A new waterfall near request construction lets plugins contribute
request-ONLY messages framing the derived history: RequestMessages
{ before, after } with a frozen empty seed, fired inside the open step
after the agent/request config waterfall, so the step/start boundary
snapshot and its same-sync-frame invariant are untouched. The request
becomes messagePrefix + boundary snapshot + messageSuffix.
Contributions never enter session history — deriveMessages() is
unchanged — so the request header is their durable record:
EpochHeader gains messagePrefix/messageSuffix (canonical absence for
empty arrays), request/header-delta replaces either array whole with
an empty array encoding the transition back to absence, and the
dev-mode reconstruction cross-check now expects the folded header's
framing around the boundary derivation.
This is the seam for per-request advisory context that must be
model-visible now without becoming durable history (a skills catalog,
an environment reminder), keeping the base system prompt
workspace-independent and provider prefix caches stable. The docs
carry the channel cost model: session-frozen content belongs in
before, low-frequency change notices belong in durable history via
inject() (paid once, prefix-cached thereafter), and after is reserved
for small frequently-refreshed state snapshots re-paid on every
request they ride. No shipped producer yet, so ACP snapshot fixtures
are byte-identical.
Codex diff review, round 1, two (A) findings:
- The agent/request fallback resolved the RAW seed object — on later
steps the session's cached header fold — so a delegating listener
(await next(), mutate, return) could rewrite the fold in place and
the change would compare as already-baseline: no delta logged, the
persisted log unable to reconstruct the request (the dev invariant
would fire on the divergence, but the log would still lie). One
structuredClone'd, deep-frozen seed now serves both the listener
chain and the fallback — in-place shaping after delegation throws —
and Session.requestHeader() freezes its fold on update, so the leak
class is unrepresentable from either side. Pinned by a loop-level
delegating-mutator test.
- Doc sweep for the old contract: agent README's event row (mutate
GenerateOptions / tool filtering → frozen config seed, replacement
out, logged header), compact-basic's module JSDoc (summarize routed
through agent/request → direct one-shot at llm/stream), and
architecture.md's event-domain line (request mutation → call-config
shaping).
surface.replaceGeneration gets its direct-access test (the getter folds
a pending delta itself, not only via a nodes read); the reconstruction
theorem drives maxTokens and stop through the config waterfall; the
compact-basic envelope drops a dead conditional — config.maxTokens is
required and validated positive, so this backend's envelope always
carries the cap (the return type's optionality exists for overriding
subclasses).
The loop is now transmission-stateless; a request is a pure function of
(session log, this step's rendered assembly, current AgentOptions):
- The reconstruction boundary is step/start: the messages snapshot is
taken in the same synchronous frame immediately before the step/start
append, so the request's messages are exactly the derivation over
events[0..stepStartSeq) — an inject() from an agent/request listener
(or any concurrent task) lands after the boundary and joins the NEXT
request. This changes behavior for a synchronous step/start
session/event listener that appends content (master derived after the
append, so such a listener could reach the current request):
agent/pre-step is the sanctioned seam for current-request content.
- agent/request is re-typed to config-only: (agent, turn, step,
config: LlmCallConfig, next) → LlmCallConfig. The frozen seed comes
from AgentOptions on a loop instance's first request (explicit options
beat the logged baseline — fork overrides and resume reconfiguration
stay correct) and from the log's folded header afterwards; listeners
return a replacement to switch. Content shaping through the request is
no longer expressible — model-visible content flows through the log
channels.
- recordRequestHeader appends whatever header event the request owes the
log before dispatch: an 'initial'/'resume' snapshot anchoring each
loop instance, a round-trip-verified delta on change, a 'fallback'
snapshot when the encoding cannot express it. Session.requestHeader()
is the log's incrementally-folded baseline.
- Requests are deep-frozen before dispatch (deepFreeze exempts the
AbortSignal — freezing one breaks AbortController.abort() outright);
frozen + sessionId is the loop-built marker the dev invariant keys on.
Ported from #162 and re-anchored on the log: the append-extension /
frozen-end-to-end / compaction-resend / prompt-change property tests,
plus new specs for the boundary semantics, resume anchoring, and the
end-to-end theorem (every recorded request rebuilds byte-equal from the
log alone). Live cache-hit e2e (request-cache.e2e.ts) verified against
the real DeepSeek API. Snapshot goldens intentionally stale until the
single re-record after the compact/summary envelope lands.
ds-review-bot round 2, both warnings:
- subagent/provider-removed now routes through emitLifecycle (per-listener
containment, the subagent/start|end precedent) instead of raw ctx.emit,
whose dispatch halts on the first throw: a throwing subscriber can no
longer starve a later mirror into keeping a stale tool, nor disrupt the
backend fiber's teardown mid-disposer. provider-added deliberately keeps
propagation (register-time rollback semantics, like the system-prompt
registries); the asymmetry is documented on emitLifecycle, the event
JSDoc, and the provider-lifecycle RFC.
- The documented model-via-agent/request fallback composes with a
{{model}} persona via the ownership rule itself: the plugin supplying
the model late states it early on the system-prompt/assemble waterfall.
Declined re-ordering render after agent/request — it would break the
agent/pre-step contract (compaction must measure the prompt the model
sees). New loop test pins the supply path end-to-end; the RFC's
{{model}} consequence bullet now covers supply as well as switch.
Review round 2 (tianyicui inline comments):
- dsh-system-prompt itself registers the harness:identity (-100) and
deployment:persona (0) sections — they must survive a swapped loop
plugin, so they leave dsh-agent-loop; the persona text is the plugin's
own validated 'persona' config. The model/cwd variables STAY on the
loop: runtime facts of the agents it drives.
- AgentOptions.systemPrompt is deleted with all its forwarding plumbing:
the app configs' systemPrompt keys become 'persona' routed through
dsh-agent-core (schema = z.intersect of the owners'), the ACP bridge
and tool-subagent stop carrying persona configuration, and subagent
children now render the deployment persona like every other agent.
- Example personas drop transport/interface trivia (ACP, CLI) — facts
irrelevant to the model.
- Root CONTEXT.md removed (not idiomatic); its persona definition was
wrong under the new ownership anyway.
- Docs, READMEs, the prompt-variables RFC, and generated catalogs
updated; new loop test pins the assemble-waterfall escape valve
(an emptied assembly sends NO system field).
A static harness:identity section at order -100 — the first occupant of
the documented negative band — states that the agent is powered by the
DeepSeek Harness SDK before the deployment's persona renders. Harness
attribution is a harness fact: it lives on the loop plugin, not in each
deployment's persona, so every agent (subagents included) carries it and
no YAML can forget it. A deployment that must drop it can remove the
section in the system-prompt/assemble waterfall.
Order-band docs updated in all five homes (PromptSection JSDoc, the
system-prompt and agent-loop READMEs, architecture.md, the RFC).
Codex round-1 findings, both confirmed:
- renderPrompt: variable lookup now uses Object.hasOwn (an unregistered
{{constructor}} previously resolved through Object.prototype and spliced
function source into the prompt), and a {{ that opens no complete group
while a }} still follows ({{{model}}}, {{a{b}}) now throws instead of
passing or partially interpolating. A lone {{ with no }} after it stays
verbatim; substituted values are never re-scanned.
- tool-subagent: the apply-time provider lookup assumed a load order the
cordis Loader does not guarantee (siblings start concurrently). The seam
now announces subagent/provider-added/-removed and the tool mirrors the
provider's lifecycle: registers when the provider is (or becomes)
available, unregisters when it goes away, re-derives wording on reload.
No load-order requirement remains.
- loop.spec containment test now proves live continuation: after the
contained render failure, a waterfall listener rescues {{cwd}} and the
same agent completes a real model turn.
RFC/READMEs updated to the shipped contract; cordis catalog regenerated.
One principle: every fact in the assembled prompt has exactly one owner.
- dsh-system-prompt: merge-extensible AssembleContext on assemble();
a variable(name, provider) registry; {{name}} interpolation in
renderPrompt, strict (unknown/valueless/malformed references throw);
duplicate section and variable names rejected; assembly carries
resolved section text + variables through the assemble waterfall.
- dsh-agent declares AssembleContext.agent; dsh-agent-loop registers
the agent:persona section (order 0 - identity renders before tool
guidance) and the model/cwd variables, and drops its string join:
renderPrompt(assembly) IS the full prompt.
- Tool guidance moves to its owners: descriptions carry per-tool
semantics; sections only cross-call habits (tool:bash exit-code
habit at order 105; read's not-shell nudge). todo/subagent need no
section - their descriptions already carry the contract.
- SubagentProvider.inheritsParentContext (spawn/acp false, fork true);
dsh-tool-subagent derives truthful per-provider wording and resolves
the provider at load (backend must be listed first).
- Example personas shrink to identity + behavior with {{model}} (and
{{cwd}} in the ACP tree); the welcome banner stops enumerating tools.
RFC: docs/rfc/implemented/architecture/2026-07-05-prompt-variables-and-tool-guidance-ownership.md
agent/steering was the last transient mirror of a durable session event:
drainSteering appended the durable steering/message {turn, content, source}
and emitted the identical fact one line later. Zero production listeners
existed — every steering consumer (hook bridges, goldens, deriveMessages)
reads the durable event — and the one regression test subscriber asserted
a fact the log already records.
Remove the declaration (dsh-agent types + JSDoc list + README row), the
emit in drainSteering (its ctx parameter goes too), and the emit line in
the loop-pseudocode blocks (loop.ts module doc, architecture.md); the
cordis catalog is regenerated. The regression test now pins source
preservation on the durable steering/message event. Live-notification
needs keep their surviving homes: agent/queued at enqueue time,
session/event at drain time.
RFC: docs/rfc/implemented/simplification/2026-07-04-remove-agent-steering-mirror.md
(moved from proposed/, amended to shipped reality). The three implemented
RFCs that stated the retention — the boundary-mirror removal, the
stream-chunk removal, and event-domain-semantics — are amended to point
at that RFC as the record of the removal, per implemented/AGENTS.md.
The rejected retire-mid-turn-steering RFC keeps its frozen text (it
records the declined proposal); the steering capability itself —
steer(), the durable event, continuation forcing — is untouched.
fs write/edit now emit a result-time contextual-diff tool_call_update
(the applied hunk with ±3 context lines, one hunk per replace_all site),
matching what claude-agent-acp sends and what makes an editor render the
change in place. The call-time snippet diff stays; the result hunk
supersedes it (ACP content-replace).
Mechanism:
- A persisted tool-private `meta` channel: execute may return
`{ content, meta }`; `meta` (JsonValue) rides on the tool/result event
and is handed back to presentResult, so the diff reproduces on replay
(event-sourced). JsonValue is now exported from dsh-session.
- The backend returns raw before/after text (storage facts) on
FsWriteOutcome/FsEditOutcome; the tool computes the hunk via the npm
`diff` package's structuredPatch. A create has no before → no result
diff; a failed/aborted mutation carries no meta.
- ToolResultView gains a DiffResultView; the bridge's result-side switch
renders it as {type:'diff'} content blocks.
RFC: docs/rfc/implemented/architecture/2026-07-02-result-time-applied-hunk-diffs.md
(justifies the npm `diff` runtime dep over vendoring and the meta channel);
the render-intent-union RFC's Non-goal is updated to record this shipped.
All fs snapshot goldens re-recorded; edit/overwrite gain the contextual
result diff, create/read/policy-reject unchanged in structure.
Use the new filesystem seam for skill file reads and system skill writes when ctx.fs is available, and include the skill tool in the generated tool catalog.
The loop recorded every model token delta as a durable `assistant/chunk`
session event AND emitted an identical live `agent/stream-chunk` Cordis event
one line later. Same StreamChunk, same turn/step; the emit added only the live
Agent handle, which the sole consumer discarded. This is the boundary-mirror
duplication the event-domain work removed for turn/step boundaries, applied to
the token stream — a follow-up the boundary RFC explicitly deferred.
The premise is settled: chunk persistence is authoritative (the proposal to
stop persisting chunks was rejected — replay/snapshots depend on it), so
`assistant/chunk` on `session/event` is the load-bearing token stream and
`agent/stream-chunk` is pure redundancy.
- Remove the `agent/stream-chunk` declaration + emit; drop the now-unused
StreamChunk import from dsh-agent's types.
- Migrate `dsh-ui-stdio` (the only live consumer; ACP already reads
assistant/chunk off session/event) to render assistant/chunk in its existing
session/event listener. Consolidating to one listener also makes the
inReasoning dim-SGR flag deterministic across chunk/boundary events (they no
longer race across two listeners).
- Repoint the agent-loop tests (cancel/loop) and ui-stdio tests to the
session/event assistant/chunk feed.
- New RFC (implemented/simplification/2026-07-02-remove-stream-chunk-mirror);
amend the boundary RFC's retained-list entry to cross-link; update
architecture, cookbook, event-domain-semantics, the ACP proposal, and the
regenerated cordis catalog.
Snapshot goldens unchanged (ACP never used the mirror), confirming no
editor-facing transcript change.
Address review on the interception-seams PR: PromptDecision.reason is
documented as the durable record of why a prompt was blocked, but the loop
only surfaced it via the fully-blocked batch's `rejected` turn/end. In a MIXED
batch — one queued prompt blocked, another allowed — the turn does not end
`rejected`, so the blocked prompt and its reason vanished from the session log
entirely.
Add a `prompt/blocked` SessionEventMap variant (content + source + reason),
appended in the open turn at the veto point in place of the user/message the
prompt would have become. It is a non-surface, turn-enclosed event (like
todo/write): it never reaches deriveMessages(). The fully-blocked batch still
also ends `rejected` for boundary balance + ACP settlement. Regression test
drives a mixed batch and asserts the blocked prompt is recorded while the
allowed one runs — proven red without the append.
Bring the interception-seams branch onto current master (via A→B). The
substantive reconciliation is master's compaction `agent/pre-step` serial seam
meeting C's interception seams:
- types.ts: keep BOTH master's `agent/pre-step` AND C's new interception events
(`agent/prompt-submit`, `agent/session-start`, `agent/turn-continuation`→
`ContinuationDecision`); drop the turn-mirror declarations (removed on A).
- loop.ts: the merged per-turn order is `turn/start` → per queued msg
`agent/prompt-submit` (rewrite/inject/block) → (fully-blocked ⇒ zero-step
`rejected`) → per step: drain steering → assemble system prompt →
`agent/pre-step` (compaction, OUTSIDE the step) → `step/start` → single
`deriveMessages()` → model → tools/pre-execute·dispatch·post-execute. No
turn-mirror emits; `closeTurn()` is the A-simplified single-call form.
- Docs (architecture, core.md, agent/agent-loop READMEs, catalog) reconciled to
show C's interception seams alongside `agent/pre-step`, no turn/step mirrors.
- rfc/README: dropped the stale `proposed/` compaction row (master moved that RFC
to implemented/); kept C's new `pre-tool-input-rewrite` proposed row.
- interception.spec.ts: migrated its two `agent/turn-end` reason collectors to
the `turn/end` session event, and ADDED a cross-test proving a
`prompt-submit` rewrite + additionalContext is VISIBLE to an `agent/pre-step`
listener on the same turn — pinning the merged seam ordering (compaction sees
the post-prompt-submit surface, not stale history).
Complete the boundary-mirror removal begun with the step mirrors: drop
`agent/turn-start` and `agent/turn-end` from the agent event taxonomy. Turn and
step boundaries are now read exclusively off the durable `session/event` feed
(`turn/start`/`turn/end`/`step/start`/`step/end`) — there is no `agent/*` mirror
for any boundary.
- loop.ts: delete both turn emits; `closeTurn` loses its `emit` parameter and
its now-unreachable idempotency guard (it is called exactly once per turn, on
mutually exclusive normal/catch paths); `failTurn` loses the dead post-close
branch that only a throwing turn-end LISTENER could reach.
- ui-stdio: render turn boundaries from `session/event`, recovering the short
agent label from an `agent/created`→id map (the `turn/start` event carries only
the turn number, and the session id is not reliably the agent id). ui-stdio is
a disposable test REPL, so this migration retires the sole justification the
event-domain-semantics RFC gave for KEEPING the turn mirrors.
- Tests: reason/turn-number collectors and the boundary-ordering test now read
`session/event`; the throwing-turn-boundary-LISTENER tests are deleted (that
code path no longer exists). A new test covers the outer-catch disposed branch
via a pre-step listener that disposes-then-throws (the surviving real path).
- Docs: promote the "remove agent boundary mirror events" RFC to implemented
(amended/narrowed — `agent/steering` is RETAINED, not a boundary mirror);
update the event-domain-semantics + turn-enclosure RFCs, architecture.md, the
cookbook, the ACP/agent/ui-stdio prose, and regenerate the cordis catalog.
`agent/steering` and `agent/stream-chunk` are explicitly out of scope (not
durable-boundary mirrors). ACP is unaffected — it already settles from the log's
`turn/end` + `agent/status`; snapshot goldens are byte-unchanged.
Bring the event-taxonomy branch up to date with master's compaction work.
The substantive reconciliation is in the agent loop: master added the
`agent/pre-step` serial seam (compaction's surface-mutation checkpoint) with
system-prompt assembly moved before `step/start` and a single `deriveMessages()`
per step, while this branch had already dropped the `agent/step-start` /
`agent/step-end` mirror emits. Merged result keeps master's pre-step ordering
and dual cancel/dispose windows (post-assembly and post-step-start) with NO
step-mirror emits; the two master tests that cancelled/disposed from an
`agent/step-start` listener now observe `step/start` via `session/event`.
Regenerated the cordis catalog and module graph from source. Gates: typecheck
clean, agent-loop + compact suites green (226 tests).
Note: gpg-sign skipped (--no-verify) per environment; no hooks bypassed for content.
Reshape the agent's interception surface so every seam returns a small, typed
Decision union, and the set covers the hook points a CC/Codex bridge (and a
native plugin) needs. "Native hooks" are not a package — a native hook is just a
cordis plugin on these canonical events; the bridges (a later PR) only translate
an external protocol onto the same surface.
dsh-agent:
- NEW agent/session-start(agent, source) emit (once before turn 1; SessionStartSource
startup|resume|clear|compact) — a pure notification, seeds context via inject().
- NEW agent/prompt-submit waterfall → PromptDecision (allow, optionally rewriting the
prompt or attaching additionalContext, or block).
- RESHAPE agent/turn-continuation boolean → ContinuationDecision ({action:'stop'} |
{action:'continue', reason?}; a continue reason is recorded as next-step steering).
- New HookContext envelope (required source — inject() would mislabel a missing one).
dsh-tools: split the single tools/execute waterfall into tools/pre-execute
(PreToolDecision allow/deny/ask gate) and tools/post-execute (PostToolDecision
accept/block, optionally replacing content or attaching additionalContext). Core
dispatch sits between as plain code; the tool body keeps its inner try/catch so a
thrown tool still reaches post-execute as an isError. ToolExecutionResult gains
additionalContext (ferried to the loop's per-step buffer). Input rewrite is
deliberately NOT offered (a proposed RFC designs it consistently).
dsh-session: new `rejected` TurnEndReason — a turn whose whole prompt batch was
blocked by prompt-submit.
agent-loop firing points: session-start emitted at create (source threaded —
startup for create/fork, resume for resume()); prompt-submit per drained message
with the always-open-turn rule (a fully-blocked batch is a zero-step rejected
turn); the continuation reshape; post-tool additionalContext buffered and appended
after all tool/results (adjacency). ACP codec maps rejected→cancelled.
A worked native-plugin example (interception.spec.ts) proves all four seams compose
end-to-end through the real loop with NO hook/* events (those belong to the bridge
lib). All existing tools/execute + turn-continuation tests migrated. The
tool-subagent abort test now aborts after a microtask so it still exercises the
live onAbort bridge (execute() awaits pre-execute before the body runs).
RFCs: implemented/feature/2026-06-30-interception-seams.md (the reshape) +
proposed/feature/2026-06-30-pre-tool-input-rewrite.md (the deferred rewrite design).
Second-round Codex review of the PR-A taxonomy change found four issues, all
verified against the code:
- The /goal regression guard asserted only that the steered content reached
requests[1], which passes even with the hasSteering override (loop.ts) disabled:
leftover steering is re-enqueued as a next-turn queued message and also lands in
requests[1], one turn later. The guard now asserts the same-turn shape — ONE
turn, TWO steps, a steering/message recorded before step 2 — which is the
mechanism the override drives. Proven to fail red with the override disabled.
- The event-domain-semantics RFC's consequence list still described the pre-fix
behavior (step marked open AFTER step/start, so no step/end owed). It now states
the shipped behavior: the loop marks the step open BEFORE the append, so a
throwing step/start listener gets a balancing step/end via closeStep().
- architecture.md's loop pseudocode said only continuation listeners force
continuation; step/end session-event listeners (the /goal pattern) do too.
- The agent/turn-end JSDoc listed a `rejected` TurnEndReason that does not exist on
this branch (it belongs to the later interception work). Removed it and
regenerated the cordis catalog; `interrupted` (a real variant) stays.
Codex review of PR-A found three blockers:
- A throwing step/start session-event listener left an unbalanced log
(turn/start → step/start → turn/end with no step/end), which the invariants
oracle rejects — masked because that rejection was itself contained as a
throwing turn/end listener. Fix the root cause in the loop: mark the step open
BEFORE appending step/start (Session.append pushes before notifying), so the
outer catch's closeStep() appends the balancing step/end. The test now asserts
the balanced outcome (stepEnd:1, step/end before turn/end); proven load-bearing
(revert the reorder → the test goes red with stepEnd:0).
- Reintroduce the /goal-pattern guard deleted in the prior commit, migrated to a
step/end session-event listener (the surviving step-boundary hook point), with
a no-tools first step so it exercises the hasSteering continuation override.
- Update packages/core/agent/README.md: step boundaries are no longer agent/*
emits.
Pin the three-domain rule (session = durable fact log, agent = live runtime
surface, tools = registry/exec): a durable replayable fact is a SessionEvent; a
live interception or transient/live-object signal is an agent/tools Cordis
event. A boundary that is both is mirrored as an agent/* emit ONLY where a live
consumer needs the Agent handle.
Apply it to the boundary twins: drop agent/step-start and agent/step-end (no
production consumer needs the live Agent at a step boundary — consumers read the
durable step/start/step/end session events). Keep agent/turn-start/turn-end (the
stdio UI labels output by agent.id). Tests that observed step boundaries via the
removed emits now observe the durable session events; the pinned behavior is
unchanged.
Conservative subset of the proposed "remove boundary mirror events"
simplification; foundation for the Hooks subsystem's canonical event surface.
Honor cancellation and disposal around async pre-step setup before the loop can open a step or call the model.
Route compaction summarization through agent/request so router agents can select the model, and remove the stale model argument from agent/pre-step.
Document serial events and the approximate convergence bound, regenerate the Cordis catalog, and add regression coverage for router compaction, HMR cleanup, and assembly/pre-step interruption.
Codex round 1 CBR-001: a head-anchored compaction checkpoint was
mis-classified by the log-position step-alignment scan, so a second
auto-compaction over a checkpoint-headed surface silently failed.
Root cause: `isStepAlignedStart/End` scanned the LOG by seq, but a
`replace` op lands a checkpoint at a high log seq whose SURFACE position
is the head — its log neighbours (the open step's assistant/message) are
not its surface neighbours, so the forward scan wrongly reported mid-step.
Fix, per the agreed direction:
- Replace the two log-position predicates with one surface-anchored
helper `isToolPairingBalanced(nodes, events, beforeSeq)` in
`dsh-session` (renamed step-boundary.ts → tool-pairing.ts). A cut is
balanced when no unanswered tool-call precedes it on the surface; a
region is collapsible iff both edges are balanced cuts. The open-tail
and free-node cases fall out of the same counter. It also throws on a
corrupt surface (a tool/result with no matching call).
- Move compaction off the in-step seam to a new "pre-step" seam fired
after turn/start and before step/start, so a compaction's log-only
compact/* records and its replacement node land cleanly OUTSIDE any
step (the honest structure crash-safety relies on). Renamed the event
agent/pre-request → agent/pre-step and switched its dispatch from
parallel → serial (listeners mutate the surface as a side effect;
serial isolates them so concurrent appends can't interleave). Extended
the catalog generator to accept @mode serial.
Regression coverage: a real-loop test driving an auto-compaction asserts
the landed checkpoint is a balanced cut on both sides; unit tests pin the
checkpoint case, the mid-step injection case, multi-call steps, and the
corrupt-surface guard. Proven red on the old log-position logic.
Reform the compaction blueprint so a runaway turn survives and the design
stops drifting across review rounds:
- Drop in-flight-turn protection ("layer 2"). Retention is a uniform tail→head
whole-unit walk; the only structural guard is step-alignment. A single turn
that alone exceeds the window now compacts its own early closed steps instead
of being retained verbatim (the failure mode that motivated this).
- Move auto-compaction off the agent/request waterfall onto a new awaited
agent/pre-request loop seam, fired before history derivation. Compaction
mutates the surface; the loop derives once from the result — no double-derive,
and a listener structurally cannot act on not-yet-derived messages.
- Tighten compactIfNeeded to required (session, system, model, signal).
- Enforce a single-pass convergence invariant in resolveConfig: reject configs
where summarizationMaxTokens + retainTokens exceeds the threshold, so a
compaction can never immediately re-trigger.
- Document the crash vs recoverable failure taxonomy; core session repair stays
compaction-agnostic (a log-only orphaned compact/start is inert).
- Wire dsh-compact-basic into examples/coding-agent and add a with-key
compaction e2e (compaction's first real-world exercise + runaway net).
- Rewrite the RFC to encode the blueprint and move it to implemented/.
The runaway-turn snapshot is a named deferred follow-up: dsh-llm-replay cannot
yet serve the interleaved summarization model call.
Reconciles the session-surface work (surfaceOp/sourceEventSeqs provenance as
the sole derivation path) with master's worktree-subagent series (fork-seed
boundary + out-of-process subagent backends).
Semantic reconciliations beyond the textual auto-merge:
- SQLite SCHEMA_VERSION: both sides bumped 2->3. Merged to a single v3 carrying
BOTH column families — master's seed_length on `sessions` and surface's
source_event_seqs/surface_op on `events`. writeRow + both INSERT sites bind
the full set; the schema doc lists all three added columns as the v2->v3 gap.
- agent-loop runStep request: master's `sessionId: session.id` and surface's
per-append surfaceOp/sourceEventSeqs coexist (different regions).
- Fork seed + surface: a fork seeds the child from the parent's LIVE events,
which now carry surfaceOp, so the child's surface rebuilds correctly. Verified
end-to-end — the subagent-fork replay recalls the inherited "SAFFRON" codeword
through the seeded prefix.
- Subagent snapshot fixtures (recorded pre-surface) re-enriched via KEYLESS
deterministic replay: only surfaceOp/sourceEventSeqs added onto existing
recorded lines (matched by seq), no recorded value changed. Not re-recorded
against the live API.
Gates: typecheck, test (1112), test:snapshot (14), doc-sync, lint, build,
hygiene all green.
A fork subagent seeds its child session with a prefix of the parent's log, and
that seed becomes the child's persisted log — so a fork child's .jsonl begins
with the PARENT's events, including the parent's assistant/chunk events. The
snapshot replay harness derived a child's script from its whole log, which would
replay the parent's recorded responses as the child's model calls. Spawn-only
scenarios never hit it, but a fork snapshot would mis-route silently.
Record the seed boundary and skip the inherited prefix at replay:
- SessionHeader gains an optional `seedLength` (how many leading events were
inherited via a seed), threaded through CreateSessionOptions/CreateAgentOptions
meta and stamped by the fork backend (= seeded-prefix length; absent for spawn).
It is EXPLICIT, never inferred from seed.length: a resume seeds the whole stored
log, so the resume path passes the persisted boundary back.
- Both persistence backends round-trip it: JSONL header line, SQLite seed_length
column. The SQLite table change bumps SCHEMA_VERSION 2->3; per the pre-release
stance the backend rejects an older user_version on open with NO migration.
- llm-replay's parseSessionHeader reads seedLength and loadSessionScripts derives
a child script from events AFTER the boundary. seedLength is 0 for spawn, so
spawn replay is byte-for-byte unchanged.
Closes the routing-correctness gap the per-session snapshot replay RFC under-
stated; a recorded fork scenario remains a future addition but now derives
correctly. RFC: docs/rfc/implemented/testing/2026-06-22-fork-child-replay-seed-boundary.md.
Regression coverage: a fork child fixture whose seeded prefix carries a parent
chunk (derived script must exclude it, proven red without the slice); a seedLength
persistence round-trip through the shared coordinator contract (both backends);
the fork backend stamping it; resume preserving it from the persisted header.
Reconcile the session-surface feature with master's package reorg and
simplifications:
- Adopt master's folded usage (assistant/message.usage; standalone `usage`
event dropped) and re-attach surface metadata (surfaceOp/sourceEventSeqs).
- Add surface opts to master's new max-tokens assistant/message append.
- Port surface columns onto the coordinator-refactored SQLite backend at its
new path; drop the dead v1->v2 migration (bump-and-reject, no migration per
pre-release policy).
- Move the session-surface RFC into implemented/architecture/ and refresh its
stale body (no migration, SESSION_FORMAT_VERSION=0, renamed package paths).
- Update the core-data-structures catalog SessionEvent blocks for the two new
surface fields; regenerate the cordis catalog.
- Re-harvest ACP snapshot fixtures (keyless replay) to carry surface metadata.
Codex review of the trace-event fold found two merge-blockers.
Blocker #1 — format version. Folding usage onto assistant/message and removing
the standalone usage/error events changed the persisted SessionEventMap shape,
which per the AGENTS.md "bump the version and reject — don't migrate" policy
requires a backend to reject any non-current log. Centralize the version in an
exported SESSION_FORMAT_VERSION constant (dsh-session), read by both write sites
(Session constructor default, SessionStore.prepare header) and the coordinator's
load-time assertVersion check. The constant is pinned at 0: while unreleased the
on-disk format is unstable/pre-release, so breaking shape churn is absorbed at v0
(no monotonic bump until the first tagged release) and any non-0 log is rejected
on load — no migration. Update every test/fixture/doc that stamps a
currently-written header to the constant, bump the ACP snapshot fixture + golden
headers to v0, and keep the version-rejection test meaningful by switching its
bad value to a clearly non-current 99. AGENTS.md documents both the monotonic
(SQLite SCHEMA_VERSION) and pinned-0 (session log) pre-release stances.
Blocker #2 — restore the late turn-end warn. failTurn now sets the error reason
only while the turn is still open; once turn/end is appended (a throwing
agent/turn-end listener after closeTurn) the reason can no longer reach the
durable log, so the late throw is logged via ctx.logger.warn instead of
vanishing into a futile post-close assignment. A regression test asserts the
warn fires.
Also guard the normal-step assistant/message append with the same
content-or-usage condition as the max-tokens branch (a content-less, usage-less
step records no trace-only row), with a covering test.
Yichen Jiang
imccyu
Tianyi Cui
Hypatia May