SESSION-02: one agent process per fly and one environment process under
the coordinator over the Unix-socket transport, compared against the
in-process composition and a dedicated-thread variant. The mode is the
only thing that changes; the composition, the coordinator, the workers
and the router are the same code in all three.
The launcher is the configured supervisor. It owns a total thread budget
with one allocation per participant, refused as BUSY before anything
starts when the total cannot cover it; the configured client, service,
worker and port identities, proved in Worker.Hello before the
coordinator pins a registration; Worker.Status health on the
supervisor's own monotonic clock at the ipc-v1 section 6 budgets; and
reaping, where Worker.Shutdown is the request and the operating system
is the guarantee.
The worker executable is a subcommand of this crate's one binary, which
is what implementation.md section 2 allows in place of a separate
worker crate.
The coordinator's fault behaviour: every failure names the participant
it is attributed to, every domain call has a caller-side deadline so a
dead participant is a diagnosed outcome rather than a hang, and failing
fences the epoch -- the boundary stops, the handles drop, and no further
transition or publication is allowed. Agent.Initialize now carries the
launcher's allocation, and an agent refuses one asking for more.
tests/processes.rs proves every acceptance bullet once per execution
mode, and the two section 4 rows SESSION-01 could not reach in one
process: a router restart during a world advance, and an old worker's
reply after a restart. measure compares the three modes at one, two and
four agents; its table is in the crate README, and it is not a capacity
claim.
The CONTRACT-01 amendment narrows Worker.Acknowledge ids to the req-<U64> form, which this
crate already read as DomainRequestId. The 1..=16 bound now comes from the contract's
MAX_ACKNOWLEDGE too, so there is one definition of it rather than two.
Review found two Memory-only tests behind a README claim that every integration test runs
twice. Both are now generated by both_transports!: the one-agent composition, and the
old-epoch refusal, which is one of the three tests the old-worker-replies row cites. The
README says which single test walks both transports inside itself instead, because it
compares their traces against each other.
step-v1 section 2 gains the mid-step pause line and a dated amendment saying why it is not
a new edge: a pause requested during a transition is the ordinary
Committing(k) -> Ready(k+1) edge followed by Ready(k+1) -> Paused(k+1), because section 6
requires the transition to finish first, so the only boundary such a pause can land on is
the one the transition just committed.
CONTRACT-01 landed its crate, so the local stand-in module goes away and the domain
scalars, method payloads, their validation, the canonical digests and the trace format
all come from the contract. `src/types.rs` is a facade over that crate plus the few
things a coordinator needs that are not part of the type contract: a session-side
DomainError, the synthetic composition's schema and event-id derivations, and the
coordinator-local ControllerIntent, PortBinding and AgentOutcome that never cross the
bus.
Consequences worth naming:
- Payloads are read and written through DomainType::from_json / to_json instead of
serde derives, so a misspelled required field fails where the contract says it
should. serde, sha2 and ryu-js leave this crate's dependencies with them.
- The step-v1 section 8 trace is the contract's TransitionTrace, with behaviour and
operational metadata already separated; the dispatch-order comparison now runs over
the contract's own behaviour encoding.
- Two things the migration found. IN_PROGRESS is raised strictly before any mutation,
so its certainty is "none", not "unknown"; the local module had it wrong.
WorldObservation::validate_against checks the views a result carries but does not
require every declared view to be present, so requiring them is made explicit in the
coordinator's phase C check, where step-v1 puts it.
- The lost-Advance-result injection now waits for the worker to report the operation
before abandoning the call, so the case it injects really is a loss after dispatch
rather than a cancellation before it.
Gates: cargo test -p fly-session (61 tests, both transports), cargo clippy
--all-targets clean, and the runnable example produces the same behaviour trace over
both transports.
The lockstep coordinator, its phase machine and a synthetic composition, as a new
workspace member. Every worker method is a Flybus RPC to an incarnation-pinned
service; the domain request ids and result caches of ipc-v1 section 5 sit in front of
every mutation.
- coordinator: the step-v1 section 3 transaction in order -- prepare every agent
concurrently, run one executor per agent in sorted agent-id order, assemble all port
controls in descriptor order, send exactly one Environment.Advance, evaluate the task
once, commit every agent concurrently, and move the committed boundary only when all
of them succeeded. Sequential, concurrent and reversed dispatch are selectable and
must agree.
- phase: the section 2 machine as an explicit edge table, Paused and Failed included,
with a committed-boundary predicate that gates pauses, captures and publication.
- clock: checked rational accumulation. A 60 Hz world with a 1 ms model tick runs
16, 17, 17 ticks and comes back to a remainder of exactly zero.
- dedup: operation keys, the cached reply with its own artifact holds, CONFLICT,
IN_PROGRESS, RESULT_EXPIRED, STALE_STEP, the lifecycle bound and Worker.Acknowledge.
- worker: the dispatch shell. Admission order and the result cache live here; the
endpoint mutex is the worker's simulation lock, so one mutation runs at a time while
Worker.Status answers from a separate cell.
- agent, environment, task: a fake model with an explicit seed and a mutation counter
the tests read, a fixed readout stub, a counter arena that seals one immutable frame
per boundary, a deterministic task and the identity executor.
- fly_session_types: the CONTRACT-01 domain types as a local stand-in, reconciled with
the shared crate in a following commit.
Tests run twice, over the in-memory transport and over a Unix socket, through the same
router: the SESSION-01 acceptance bullets and every section 4 failure-injection row
that applies to this slice.
