| Internet-Draft | Composite Execution Finality | September 2026 |
| Das | Expires 20 March 2027 | [Page] |
An agent, a payment orchestrator, or a control-plane applicator often intends one Candidate Act that would become real only as several consequences: a settlement post, a ledger write, a tool invoke, a notification, a radio enable. [DAS-HANDLE] specifies verify, consume, and receipt at one Finality Sink. It does not say what "the act was permitted" means when sink S1 has consumed and posted and sink S2 has rejected, timed out, or committed a different digest.¶
Existing distributed-transaction tools already address adjacent problems. Two-phase commit, XA, sagas, TCC, transactional outbox, and workflow engines coordinate steps. OAuth, WIMSE, RATS, and SCITT still name identity, environment, and signed statements. None of them, by themselves, bind N sink-local Execution Handles to one composite Act Digest and require that no child consequence become externally effective unless every required child reaches a defined terminal state.¶
This document specifies Composite Candidate Acts, child handles, a coordinator that may only prepare, a two-phase consume rule, and the distinction between prevention (no child commits unless the composite closes) and mitigation (compensate after a partial post). Compensation is itself a Candidate Act. It is not a silent undo and not a license to skip verify on the original child.¶
The join is closed by a durable, linearizable Composite Decision Log holding one value per composite: empty, COMMIT, or ABORT, written only by compare-and-swap so that the first writer wins. The coordinator MUST win the log before sending a decision to any child. A prepared child whose reservation timer expires MUST consult the log: it commits if COMMIT is recorded, releases if ABORT is recorded, attempts its own compare-and-swap of ABORT if the log is empty, and holds its reservation (HOLD) only if the log is unreachable. No child acts on silence alone.¶
This is not a new consensus protocol and not a claim that XA is obsolete. Profiles that cannot obtain prepare-from-every-sink, or cannot reach a durable linearizable decision log, MUST NOT claim all-or-none prevention.¶
Three rejections are expected and are treated as design constraints. "Saga plus handle is enough" is accepted when each saga step already reconstructs the live child, consumes a child handle, and cannot log SUCCESS after a required child rejects; this draft then shrinks to join fields. Prepare across N sinks is a latency tax only if consume-state is global; it is per child handle, and a no_prepare mail or MCP child must use the mitigation profile rather than pretend 2PC. Child sinks reconstruct only their own pending effect, not a mesh-wide CAD. Reviewers who would reject on saga, performance, or reconstruction grounds are asked to read those sections before discarding the document. Criticism, including "this should stay a note in the handle draft," remains invited.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
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This Internet-Draft will expire on 20 March 2027.¶
Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
This Internet-Draft is
draft-das-composite-execution-finality-01.
It specifies how several handle-using sinks join as one
Composite Candidate Act: child handles, prepare/commit/abort,
ALL_REQUIRED prevention, and compensation as a new act.
Single-sink objects remain in [DAS-HANDLE];
code points remain in [DAS-REG].¶
A composite intent C is authorized as a unit: pay vendor X AND write the invoice AND notify finance. If the settlement sink consumes its handle and posts, and the notification sink times out, operators still say "the agent paid." The Candidate Act that was reviewed was not the world that occurred. No child token was forged. The failure is split effectuation of one intended act.¶
Intended C = { pay X, book invoice, notify finance }
+-- S1 SETTLEMENT consume + post EFFECTUATED
C ---+-- S2 CONTROL timeout NON_EFFECTIVE
+-- S3 TOOL never invoked NON_EFFECTIVE
Reviewed act: C
Occurred world: pay X only
Partial commit
!=
composite finality
Two-phase commit and XA serialize prepare/commit across resource managers. Sagas and TCC specify forward actions plus compensations. Outbox and workflow engines order side effects. Those tools should be used. They do not define an Execution Handle per child sink, do not reconstruct each live child act, and do not make "compensation" a second handled Candidate Act.¶
[DAS-HANDLE] closes possession-versus-authority at one
boundary. After that draft, each child can be locally correct and
the composite still wrong. Registries reserve COMPOSITE
as a class and a sink type [DAS-REG]. They do not
specify the protocol.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals.¶
If C is the act that was authorized, and only a proper subset of C's required children have become externally effective, was C effectuated?¶
Prevention profile:
C is EFFECTUATED
iff every required child is EFFECTUATED
under handles bound to C
and no extra child effect is attributed to C.
Otherwise C remains NON_EFFECTIVE
even if some child already moved money or iron.
¶
That last sentence is the operational cost. If a profile cannot prevent the child post, it must not advertise all-or-none prevention.¶
An enterprise agent is allowed to settle a vendor invoice only as a unit with the ERP booking and an audit mail. Settlement posts in 80 ms. ERP is in a change window. Mail is a third-party API with no prepare. A coordinator that "retries notify later" has not effectuated C. It has effectuated a different act: pay-without-book.¶
Authorized C17 = pay + book + notify [all required]
After S1 post, S2 reject:
world = paid, not booked
C17 = still NON_EFFECTIVE
C18 = "notify later about a payment already posted"
is a new CAD
and needs its own handle
The attacker need not forge handles. Relevant failures:¶
Goal: define when a multi-sink Candidate Act may be called EFFECTUATED, PREPARED, ABORTED, or COMPENSATING, using the objects in [DAS-HANDLE].¶
Non-goals: a new Paxos/Raft; replacing XA or workflow engines; requiring every SaaS to implement prepare; claiming exactly-once delivery across the open Internet; automatic legal netting of a posted payment.¶
Composite Candidate Act (C): A Candidate Act whose intended consequence is the conjunction of two or more child consequences.¶
Child Act C_i: The component that one sink would effectuate.¶
Required child: A child that MUST reach EFFECTUATED for C to reach EFFECTUATED.¶
Optional child: A child that MUST NOT block C if it fails, and MUST NOT be advertised as part of C's authorized unit if it is skipped. Optional children SHOULD be separate acts.¶
Coordinator: The component that records composite state. It is not a Finality Sink for a child effect unless it is also that child's sink.¶
Prepare: Child sink has verified the live child act, reserved consume-state, and promises not to post until the Composite Decision Log records COMMIT, and not to release until it records ABORT.¶
Composite Decision Log (CDL): A durable, linearizable register holding one value per composite identifier: empty, COMMIT, or ABORT. Its only write operation is CAS(C, empty -> v). The first successful write is final; every later write fails and returns the recorded value. The coordinator and every prepared required child can read it and attempt the write. "Queryable" is not sufficient: an eventually consistent store cannot provide first-writer-wins.¶
HOLD: The child-local state of a prepared child that cannot read or write the CDL. A child in HOLD produces no external effect and keeps its reservation.¶
Compensation act: A new Candidate Act that would reverse or contain a child effect that already escaped. It uses a new handle.¶
A composite CAD is a CAD whose consequence_class and
coordinator sink_type are COMPOSITE
[DAS-REG]. It MUST list children explicitly.¶
composite_cad = {
candidate_act_id,
composite_act_digest, // d(C), see below
consequence_class: "COMPOSITE",
children: [
{ child_id, cad_i, sink_i, required: true|false },
...
],
join_rule: "ALL_REQUIRED",
expires_at,
generations
}
ALL_REQUIRED:
every child with required=true must EFFECTUATE
for C to EFFECTUATE.
QUORUM / BEST_EFFORT:
MUST NOT be used in a prevention profile
for FINANCIAL, PHYSICAL, RF, CLINICAL, MODEL_RELEASE.
¶
The composite Act Digest binds the whole child list, not only an
identifier. Children are sorted by child_id before
canonicalization so that the digest does not depend on
presentation order.¶
d(C) = Hash( Canon( join_rule,
sort_by_id[ (id_i, d(C_i), S_i, required_i) ]
for all children i ) )
¶
Hash and Canon are those of [DAS-HANDLE]. Adding, removing, reordering-as-required, or substituting a child changes d(C).¶
Each required child has its own Execution Handle EH_i issued by the PED. EH_i MUST bind:¶
act_digest of child CAD_i¶
sink_id of S_i¶
composite_id = C.candidate_act_id¶
composite_digest = d(C), the composite Act Digest¶
reuse_policy compatible with the child class¶
A child handle MUST NOT be accepted at a sink whose consume would not serve that composite_id and composite_digest. Binding only composite_id is insufficient: an attacker who can alter the child list while keeping the identifier would otherwise obtain child handles that still match. Presenting EH_i for a standalone payment that is not C is EF-023 or EF-040 [DAS-REG].¶
The coordinator MAY hold a composite handle EH_C whose digest is the composite Act Digest. EH_C authorizes the coordinator to drive prepare/commit/abort. It does not authorize S_i to post.¶
issue
|
v
NON_EFFECTIVE
|
children verify
v
PREPARED --- CDL CAS ABORT wins ---> ABORTED
| (coordinator or child)
CDL CAS COMMIT wins
v
COMMIT_DECIDED
|
every required child driven to commit
v
EFFECTUATED
If any required child already posted
and others cannot:
EFFECTUATED is forbidden
|
v
COMPENSATING -- compensation C' --> CONTAINED
|
+--> UNKNOWN (compensation also split)
Prevention profile forbids entering COMPENSATING
because a required child posted before join.
Child-local, on reservation timer:
CDL = COMMIT --> commit (EFFECTUATED)
CDL = ABORT --> release (RELEASED)
CDL = empty --> CAS ABORT
won --> release
lost --> commit (COMMIT won)
CDL unreachable --> HOLD, no post, EF-048
HOLD, CDL readable --> re-evaluate as above
Child sinks use the handle draft states locally: verify, consume (here: reserve / commit / abort), receipt. C's state is a join of those receipts, not a vote by the model that proposed C.¶
Each S_i MUST reconstruct live child CAD_i from the pending local effect, not from a coordinator-supplied blob alone [DAS-HANDLE]. Coordinator-supplied CAD_i is a hint. Digest mismatch is EF-023.¶
Prepare is consume-state reservation without external effect.¶
S_i.prepare(EH_i, live_cad_i):
verify handle and reconstruct digest
if fail: receipt REJECTED, do not reserve
if consume-store down: EF-081, fail closed
reserve EH_i (not yet posted)
return PREPARED
Coordinator:
if any required child not PREPARED
before deadline:
Coordinator.abort(C) // via the CDL
¶
A sink that cannot reserve without posting (typical third-party
mail or card API) MUST be declared no_prepare=true. A
composite that includes a required no_prepare sink MUST NOT use
the prevention profile. It MAY use mitigation: post last, or
accept COMPENSATING.¶
Coordinator.commit(C):
require all required children PREPARED
require EH_C still current // checked immediately
// before the CAS
v = CDL.CAS(C, empty -> COMMIT)
if v == ABORT: // a child TTL or an
release_all_prepared(C) // earlier abort won
C = ABORTED
return
C = COMMIT_DECIDED // point of no return
for each required S_i:
r = retry_until_terminal(S_i.commit, EH_i)
// a PREPARED child promised to post; transient
// failure is retried, never treated as abort
if all required EFFECTUATED:
C = EFFECTUATED
emit composite receipt
else:
// reachable only if a prepared sink cannot post
// (broken promise, sink destroyed, legal stop)
C = COMPENSATING // EF-047
Coordinator.abort(C):
v = CDL.CAS(C, empty -> ABORT)
if v == COMMIT: // lost to an earlier
Coordinator.commit_redrive(C) // COMMIT: do not abort
return
for each PREPARED S_i:
S_i.abort(EH_i) // RELEASED, no post
C = ABORTED
¶
The composite finality point is the successful CAS of
COMMIT, not the first child post. Child currentness
(generations, revocation) is evaluated inside each child's
serialized prepare section [DAS-HANDLE], and
EH_C currentness is re-checked immediately before the
CAS. A revocation that arrives after COMMIT is recorded
applies to an act that is already final; it is handled by a new
compensation act (Section 13), not by releasing
a child that the log says must commit.¶
| Rule | C EFFECTUATED when | Prevention claim |
|---|---|---|
| ALL_REQUIRED | every required child EFFECTUATED | Yes, if every required sink supports prepare |
| ALL_THEN_OPTIONAL | required set EFFECTUATED; optional attempted | Only over the required set |
| QUORUM(k) | any k children | No for high-consequence classes |
| BEST_EFFORT | coordinator tried | Never |
If a required child has already posted, C cannot become EFFECTUATED and cannot become cleanly ABORTED. A compensation Candidate Act C' MAY be issued: reverse the post, hold the funds, disable the radio, retract the tool side effect.¶
EH_pay CONSUMED + posted
EH_book REJECTED
Forbidden:
S_pay.undo(EH_pay) // handle already consumed
Required:
C' = "return funds for composite C17"
new CAD', new EH'
S_pay.verify/consume(EH')
C = COMPENSATING then CONTAINED
only if C' EFFECTUATED
Success of C' is not success of C. Receipts MUST keep the two identifiers distinct. Failure of C' leaves C in UNKNOWN containment and MUST be visible.¶
CDL.CAS(C, empty -> COMMIT) or CDL.CAS(C, empty -> ABORT) before sending that decision to any child. Prepare messages are sent before any decision exists.¶
COMMIT, it MUST re-drive commit to every required child not yet EFFECTUATED. If the CDL is empty, it MAY write ABORT.¶
COMMIT MUST re-drive commit and MUST NOT send abort.¶
Classic two-phase commit is blocking. The following two rules cannot both hold in a prevention profile:¶
If the coordinator writes COMMIT, S1 posts, and then dies before S2 hears COMMIT, S2's local TTL abort produces the partial commit this draft called unreachable. That path is reachable unless children consult a durable decision before acting on a timer.¶
A log that children can only query is not enough on its own. If the coordinator dies before deciding, every child reads an empty log and cannot safely release, because the coordinator might still write COMMIT. Every child would then block. The CDL removes that case: a child may itself write ABORT into an empty log, and because the write is compare-and-swap, the coordinator can no longer write COMMIT afterwards. HOLD is reserved for the case where the log itself is unreachable.¶
Forbidden pair (prevention profile):
coordinator.decision == COMMIT
AND
some required child locally ABORTS on TTL
Required instead:
coordinator wins CDL.CAS before sending
COMMIT or ABORT to any child
child reservation timer fires
-> read CDL[C]
-> COMMIT: commit locally
-> ABORT: release (RELEASED)
-> empty: CAS(C, empty -> ABORT)
won: release
lost: commit
-> unreachable: HOLD, no post, EF-048
retry the log; alert operator
Dead coordinator, no decision:
first child timer writes ABORT
composite ABORTED, no child posts
Dead coordinator, COMMIT recorded:
every child timer reads COMMIT
composite closes
If the deployment cannot provide a durable,
linearizable CDL:
it MUST NOT claim PreventionWellFormed
it MAY use hold-until-operator
it MUST treat a discovered split as
C = COMPENSATING, reason EF-047
¶
Automatic commit on coordinator silence remains forbidden.
Automatic release on a child timer is forbidden unless the child's
own CAS of ABORT succeeds or the log already records ABORT. Timers
trigger a decision attempt; they never substitute for a decision.
An operator resolution procedure, if a profile defines one, MUST
itself write through CDL.CAS so that a manual decision
cannot contradict an automatic one. A child in HOLD SHOULD raise an
operator alert; for sinks where a long-held reservation is itself
harmful (for example a held payment authorization), the profile
SHOULD document the maximum acceptable HOLD duration and the
escalation path.¶
Let C have required index set R. Child i has handle H_i, sink S_i, live act C_i(t), and local state q_i(t). The identities below are the same join as the prepare/commit pseudocode. Child digests use the hash function of [DAS-HANDLE]. A TLA+ model of this join is well-formed only if COMMIT followed by child TTL cannot reach Split under PreventionWellFormed.¶
Posted(C,t) = { i in R | q_i(t) = EFFECTUATED }
Effect(C,t) iff Posted(C,t) = R
and forall i in R. d(C_i(t)) = H_i.d
and forall i in R. H_i.composite_id = C.id
and forall i in R. H_i.composite_digest = d(C)
Abort(C,t) iff Posted(C,t) = empty
and CDL(C) = ABORT
Split(C,t) iff Posted(C,t) nonempty and Posted(C,t) != R
and ( CDL(C) != COMMIT
or exists i in R. CannotPost(i,t) )
Split(C,t) => COMPENSATING with EF-047
Closing(C,t) iff CDL(C) = COMMIT
and Posted(C,t) nonempty and Posted(C,t) != R
and forall i in R. not CannotPost(i,t)
Closing(C,t) => COMMIT_DECIDED (transient, not a split)
reject, deadline, operator abort, or child timer
=> attempt CDL.CAS(C, empty -> ABORT)
(never a direct transition to Abort)
CDL(C) = COMMIT => no PREPARED child is released
Timer: COMMIT -> commit
ABORT -> release
empty -> CAS ABORT (won: release; lost: commit)
unreachable -> HOLD
¶
Required(C) = { i | child_i.required }
Prepared(C) = { i in Required(C) | S_i.state == PREPARED }
Posted(C) = { i in Required(C) | S_i.state == EFFECTUATED }
Rejected(C) = { i in Required(C) | S_i.state == REJECTED }
C.EFFECTUATED iff Posted(C) == Required(C)
AND no child digest diverged
AND join_rule == ALL_REQUIRED
or ALL_THEN_OPTIONAL
C.ABORTED iff Posted(C) empty
AND CDL(C) == ABORT
C.COMMIT_DECIDED iff CDL(C) == COMMIT
AND Posted(C) != Required(C)
// transient: every required child
// is being driven to EFFECTUATED
C.COMPENSATING iff Posted(C) nonempty
AND Posted(C) != Required(C)
AND some required child can no longer post
PreventionWellFormed(C) iff
join_rule == ALL_REQUIRED
AND every required S_i supports prepare
AND no required S_i has no_prepare
AND a durable, linearizable CDL is reachable
by the coordinator and every required child
AND no child releases or posts on a timer
except as the CDL dictates
PreventionWellFormed(C) == false
==> MUST NOT claim all-or-none prevention
¶
This section states the properties the join claims and the assumptions each property needs. Safety (no split) depends only on the Composite Decision Log and child behaviour. Closure (the composite eventually ends) additionally depends on sinks keeping the promise made at prepare and on fair re-drive. The two claims are kept separate so that a deployment can state which one it provides.¶
Notation: bot is the empty value; CDL(C,t) is the value recorded for C at time t; Read_x(C,t) is a read by party x.¶
A1 Stability:
CDL(C,t) != bot
=> forall t' >= t. CDL(C,t') = CDL(C,t)
A2 Single value (linearizability):
Read_x(C,t) = v and Read_y(C,t') = v'
and v != bot and v' != bot
=> v = v'
A3 First writer wins:
CAS_x(C, bot -> v) succeeds at t
=> CDL(C,t) = v and every later CAS fails
and returns v
¶
I1 Post_i(t)
=> exists t0 <= t. Read_i(C,t0) = COMMIT
I2 Release_i(t)
=> exists t0 <= t. Read_i(C,t0) = ABORT
or WonCAS_i(C, ABORT, t0)
I3 Post_i(t)
=> Prepared_i(t_p) with t_p < t_dec
where t_dec is the time of the successful
CAS(C, bot -> COMMIT)
I4 Hold_i(t)
=> not Post_i(t) and not Release_i(t)
¶
Theorem 1 (Safety). Under A1, A2, A3, I1, I2:
not exists i, j in R.
Posted_i and Released_j
Proof.
Posted_i => some party read COMMIT (I1)
Released_j => some party read ABORT
or won CAS ABORT (I2, A3)
A1 and A2 forbid the log holding both
COMMIT and ABORT for C.
Hence no execution has both. QED
¶
Theorem 1 does not require the coordinator to be correct, alive, or honest. It requires only that the log satisfies A1 to A3 and that every required child obeys I1 and I2.¶
A4 Promise kept:
CDL(C) = COMMIT => forall i in R. not CannotPost(i)
A5 Weak fairness:
a party that can re-drive commit, or retry a
reachable log, eventually does so
A6 Log eventually reachable:
<>[] Reachable(CDL)
Theorem 2 (Closure). Under Theorem 1, A4, A5, A6:
<>( Effect(C) or Abort(C) )
Sketch.
If CDL(C) stays bot, the first expiring child
timer writes ABORT once the log is reachable
(A5, A6), so Abort(C).
If CDL(C) = COMMIT, every required child is
driven to Post (A4, A5), so Effect(C).
By A1 exactly one branch applies. QED
¶
If A4 fails for some child (a prepared sink is destroyed, or a legal stop prevents posting), Theorem 1 still holds for all other children but the composite enters COMPENSATING with EF-047. That case is a broken prepare promise, not a protocol split.¶
Coordinator dead before deciding, log reachable:
T_abort <= min_i TTL_i + delta_cas
HOLD duration for child i:
T_hold(i) <= T_unreach(CDL) + TTL_i + delta_cas
Commit completion after t_dec, with at most k
retries per child and per-attempt time delta_post:
T_close <= t_dec + |R| * k * delta_post
(sequential; parallel re-drive gives
max_i instead of the sum)
¶
T_unreach(CDL) is outside the protocol. It is why log availability belongs to the trusted computing base and why a profile SHOULD state a maximum acceptable HOLD duration.¶
t_prep_i = time child i entered PREPARED
t_dec = time of successful CAS(C, bot -> COMMIT)
Effect(C)
=> forall i in R. Current(H_i.g, t_prep_i)
and Current(EH_C.g, t_dec)
and t_dec >= max_i t_prep_i
Revoked(H_i, t) with t > t_dec
=> handled by a compensation act C'
not by releasing child i
¶
Effect(C') does not imply Effect(C)
Contained(C) iff Split(C)
and Effect(C')
and C'.parent = C.id
and C'.handle != any H_i
Failed containment:
Split(C) and not Effect(C') => UNKNOWN
¶
function effectuate_composite(C, handles, cdl):
if not PreventionWellFormed(C):
return mitigation_mode(C, handles) # different claim
prepared = []
for child in required(C):
live = child.sink.reconstruct()
r = child.sink.prepare(handles[child], live, C.id)
if r.decision != "PREPARED":
return abort_via_log(C, prepared, cdl, r.reason_code)
prepared.append(child)
if not ehc_current(C): # re-check before CAS
return abort_via_log(C, prepared, cdl, "EF-041")
if cdl.cas(C.id, EMPTY, COMMIT) == ABORT:
release_all(prepared) # a child timer won
return receipt(C, "ABORTED", "EF-048")
for child in required(C): # point of no return
r = retry_until_terminal(child.sink.commit, handles[child])
if r.decision != "EFFECTUATED":
return receipt(C, "COMPENSATING", "EF-047")
return receipt(C, "EFFECTUATED", consume_outcome="CONSUMED")
function abort_via_log(C, prepared, cdl, code):
if cdl.cas(C.id, EMPTY, ABORT) == COMMIT:
return redrive_commit(C) # too late to abort
release_all(prepared)
return receipt(C, "ABORTED", code)
function child_on_reservation_timer(child, C_id, cdl):
try:
v = cdl.read(C_id)
if v == EMPTY:
v = cdl.cas(C_id, EMPTY, ABORT) # returns final value
except Unreachable:
child.state = HOLD # no post, keep reserve
alert_operator(C_id)
return report("EF-048")
if v == ABORT:
child.release() # RELEASED
else:
child.commit() # COMMIT is final
function compensate(C, child_posted):
C2 = new_cad(reverse_of(child_posted), parent=C.id)
eh2 = PED.issue(C2)
return child_posted.sink.verify_consume(eh2)
¶
| Existing tool | Supplies | Still required |
|---|---|---|
| XA / 2PC | Prepare/commit wire to RMs | Child Act Digest + handle bind |
| Saga / TCC | Forward + compensate graph | Compensation as new handle; no silent undo |
| Outbox / workflow | Ordered jobs, retries | Retries are new attempts, not C success |
| SCITT | Logged composite receipt | Log is not child commit |
| Single-sink handle | Local authority | This join |
ef-composite-strict: ALL_REQUIRED, every required sink supports prepare, a durable linearizable Composite Decision Log written only by compare-and-swap, child timers act only through that log (CAS ABORT if empty, HOLD if unreachable), compensation is a new act, coordinator receipt insufficient.¶
ef-composite-mitigation: at least one required sink is no_prepare, or no durable linearizable decision log is available; document the escaped-effect window; MUST NOT claim prevention.¶
The invitation in the abstract to treat "saga plus handle is enough" as a successful review outcome is deliberate. The same is true of the performance and reconstruction objections. This section states where those objections are accepted.¶
If each saga step is already a handle-using sink — reconstruct live child, prepare or consume, fail closed — then this draft is a join profile on top of that saga, not a replacement for it. XA resource managers that expose prepare, and PSP authorize/capture pairs, are the same pattern under other names.¶
The residual cases this draft still names:¶
Accepted:
saga / XA / workflow
AS coordinator
child Execution Handle
AS per-sink authority
Not accepted as prevention:
saga success
without child PREPARED/EFFECTUATED receipts
compensate(original_token)
after the original handle is CONSUMED
BEST_EFFORT notify
advertised as C EFFECTUATED
¶
If reviewers produce a saga profile that already forbids those four cases, this document should shrink to that profile plus the composite CAD fields. That outcome is welcome.¶
ALL_REQUIRED prepare adds one reservation round to every required child before any child posts. On a payment rail that is already authorize-then-capture, that round already exists. On a three-sink agent path where mail cannot prepare, the honest profile is mitigation: do not claim all-or-none, or split notify into a later act.¶
Consume-state remains per child handle, not one lock for the whole composite. The coordinator persists join state; it does not serialize unrelated composites. Automatic commit on coordinator silence is still forbidden in the strict profile, because that is how partial posts happen.¶
Children do not reconstruct the composite CAD. Each sink reconstructs only its child: the payment it would post, the tool it would invoke, the row it would write. The coordinator compares child receipts and the composite digest over the declared child list. A mesh hop that is not a child sink does not reconstruct anything.¶
If a child sink cannot observe the fields that change its own effect, that child cannot be in a prevention-profile composite. It can be an optional later act. Hiding that limitation inside a caller-supplied composite blob is how split reality occurs.¶
A minimal demonstration is more useful than another join diagram: one MCP (or payment) middleware that consumes a child handle, one second sink that can prepare, and a coordinator that aborts when the second child rejects — including the case where a prompt-injected destination changes only one child's digest. This document does not ship that code. An implementation that does is invited.¶
Agent products already chain tools: pay, ticket, mail, CRM write. Cloud workflow services already run sagas. PSPs already split authorize and capture. Those roadmaps are complementary. This document does not assert that any named orchestrator is unsafe, incomplete, or required to implement prepare.¶
PSP authorize/capture ~ prepare/commit at SETTLEMENT Cloud workflow / saga ~ coordinator + compensation graph MCP tool chain ~ children; often no_prepare Agent runtime ~ proposer of C, not the join¶
A PSP capture API that already holds an authorization and voids it on timeout is already a prepare-capable SETTLEMENT sink under another name. An MCP server that cannot reserve a Gmail send is a no_prepare TOOL_DISPATCH sink. Putting both in one "strict" composite would be a mis-profile, not a vendor defect.¶
Named companies are not claimed as reviewers, implementers, or endorsers. Corrections and requests to remove a framing are invited. Silence is not agreement.¶
This document does not claim that any named group should adopt the work.¶
Relevant only if child handles are token profiles. OAuth should not own actuation join.¶
Relevant if child actors are workloads on different hops. Workload identity is not composite join.¶
Relevant to coordinator HTTP resources and problem+json mapping of EF-047 / COMPENSATING and EF-048 / HOLD.¶
Useful for whether all-or-none across administrative domains is in scope for the IETF at all.¶
Individual -00. No IANA request in this revision beyond codes already reserved in [DAS-REG].¶
Coordinator compromise is not child-sink compromise. A malicious
or failed coordinator can withhold a decision, but it cannot make a
child post without a recorded COMMIT, and it cannot hold
reservations indefinitely while the log is reachable, because any
prepared child can write ABORT into an empty log.¶
Child sinks MUST NOT release a PREPARED reservation on a timer when
COMMIT may already be recorded. They MUST consult the log:
COMMIT commits, ABORT releases, an empty log allows
a child CAS of ABORT, and an unreachable log leads to HOLD.¶
The integrity and availability of the Composite Decision Log are part of the trusted computing base for the prevention claim. An attacker who can rewrite a recorded value, or who can make two readers observe different values, can split the composite. An attacker who can make the log unreachable can keep reservations in HOLD. Profiles SHOULD replicate the log with a consensus protocol and SHOULD authenticate writers.¶
Child CAS of ABORT means a compromised or misconfigured
required child can force a composite to abort by writing
ABORT early. That is a liveness attack, not a safety break:
no child posts, and no split occurs. Profiles MAY restrict early
child writes to children whose reservation timer has actually expired
and SHOULD log the writer identity of every CAS.¶
Treating a coordinator signature as a settlement receipt recreates bearer authority at the wrong layer. Quorum join on financial or physical children is a safety bug, not an availability feature.¶
A composite CAD lists every child destination. That list can reveal a payment, a patient-adjacent system, and a mail target together. Coordinators SHOULD store child digests and sink ids, and SHOULD omit raw arguments from composite receipts sent off-path.¶
This version does not request IANA action. It uses
COMPOSITE, EF-047 PARTIAL_COMMIT, and the
composite states proposed in [DAS-REG]. It also
uses EF-048 DECISION_LOG_UNREACHABLE, the
COMMIT_DECIDED composite state, the HOLD child
decision, and the ef-composite-strict and
ef-composite-mitigation profile identifiers, which are
expected to be added to [DAS-REG] in its next
revision.¶
The most useful criticism is that XA plus per-resource handles already yields this join, or that mitigation sagas are the only honest Internet profile. Either result should shrink the draft. Named-product corrections are welcome. Silence is not endorsement.¶
Local handle correctness at each sink does not make a multi-sink intent final. C is effectuated only when every required child is effectuated under handles bound to C. If a required child cannot prepare, the honest claim is mitigation plus a later compensation act — not all-or-none prevention.¶
CHILD POST
!=
COMPOSITE FINALITY
SAGA COMPENSATION
!=
THE ORIGINAL ACT SUCCEEDED
PREPARE ALL REQUIRED
or
DO NOT CLAIM PREVENTION
¶