Preserve the V3 system-prompt projection while adopting master’s per-agent frozen-message provenance and frontend performance gates. Keep benchmark workload admission and diagnostics fixes intact, and retain both migration and first-open/reopen lifecycle guarantees.
Preserve system/message persistence while adopting named persona prefix/suffix and environment facts after reusable instructions. Resolve the Web assertion against the logged system message, not retired header.system. Keep the existing protected V3 integration PR as the root publication path; no rules are bypassed.
Cause: SystemPromptProjection skipped the first empty rendered prompt. The initial admitted user then occupied surface node zero, so a later nonempty prompt appended behind user history. Routes without in-history system support lost the leading system role; pi-ai demotes a non-leading system message to user content.
Fix: append the initial system node even when its content is empty. The existing loop commit order reserves node zero before admitted user messages; later prompt text replaces that node. Empty content still derives to no wire message. Keep retained-node replacement, clearing, multi-system handling, and pi-ai conversion unchanged; this addresses only the reviewed PR3476 initial-empty finding, not PR3483.
Tests: added initial-empty projection and two-turn loop regressions for empty wire output, reserved surface head, later leading system role, replacement intent, and series header. Negative control failed before the source fix. Focused projection/runtime-context/loop/request-reconstruction/session-surface/pi-ai-context suites passed 176 tests; exact runtime-context.ts coverage is 100% statements, branches, functions, and lines. test:docs passed all 15 gates. Updated README EN/ZH, architecture map and owning architecture note; recorded all three translation pairs. Broad doc-sync/lint stopped at parent request for combined-layer validation. No normalize.ts conflict-comment edit.
Consolidate the representation-change PR and its rebase reconciliations into one baseline. Preserve the exact tree and keep the in-history feature in the dependent PR. Follow-up fixes remain separate.
Write handles now hold a durable lease (session.lock.json beside the
log): a random owner token, diagnostic pid, and an expiry. Acquisition
wins by exclusive create; a second process's create or write open rejects
while the record is unrenewed for less than leaseTtlMs (default 5 min),
and takes over after that — a crashed holder is waited out, never
reclaimed by pid. The holder renews every leaseRenewIntervalMs (default
4 min); a renewal that finds a foreign, vanished, or expired record — or
fails outright — marks the lease lost permanently, so every later
append/flush rejects with SessionOwnershipLostError while reads continue.
Close releases the record; read handles never touch it. Takeover of an
expired record is eventually exclusive: a replaced holder stops within
one renewal interval.
Refs #3245
The `start` frame and the reconnect baseline attempt carried a wall-clock
`startedTime` that no Host or Client consumer read: the Host accumulator
and the Client reconciler copied it into their attempt maps and nothing
looked at it again. Presentation frames now carry only the coordinates
consumers use (attempt, revision, turn, step, chunk index, and v1 seq
provenance); the type-equivalence block, event graph, READMEs, and the
live-stream Agent Note follow the type.
The persistence seam is now create/open/stat/list returning per-session
SessionHandles (read/append/flush/close); every log read and write flows
through the owning handle. The seam package exports only the service and
handle contracts, consumer-visible errors, and pure durable-data
validation helpers; each backend owns its complete storage runtime, and
the shared contract suites pin equivalent observable behavior. The
backend routes published sessions' live events by id into the active
write handle; agent-loop only acquires, seeds, and closes the handle.
Resume appends interruptedTurnClosers through its write handle;
session-query owns the revision-keyed cold cache. Legacy-only surfaces
are removed in the same swap: locate/readRaw/supportsRawArtifacts, the
legacy event-shape read migration, zstd torn-frame salvage,
DSH_SESSION_JSONL, and hook transcript_path population; a torn final
zstd frame is discarded whole; the session-list cold blank probe returns
on stat metadata (eventCount derived from the last physical row,
sizeBytes). The WebUI ZIP export serializes the logical log from a read
handle, so both backends export identically.
Refs #3245
Tianyi Cui