Individual Submission S. Das Internet-Draft Independent Intended status: Informational 16 September 2026 Expires: 20 March 2027 Partial Commit Is Not Finality: Composite Candidate Acts Across Multiple Finality Sinks draft-das-composite-execution-finality-01 Abstract 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. Das Expires 20 March 2027 [Page 1] Internet-Draft Composite Execution Finality September 2026 This is not a new consensus protocol and not a claim that XA is obsolete.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. Status of This Memo 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/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 20 March 2027. Copyright Notice 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. Das Expires 20 March 2027 [Page 2] Internet-Draft Composite Execution Finality September 2026 Table of Contents 1. What This Version (-01) Contains . . . . . . . . . . . . . . 4 1.1. Contents of -01 . . . . . . . . . . . . . . . . . . . . . 4 1.2. Changes from -00 . . . . . . . . . . . . . . . . . . . . 5 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. Vulnerability: One Intent, Split Reality . . . . . . . . 6 2.2. Existing Mechanisms Already Coordinate Steps . . . . . . 6 2.3. Residual Gap After a Single-Sink Handle . . . . . . . . . 7 2.4. What This Document Introduces . . . . . . . . . . . . . . 7 3. Conventions and Requirements Language . . . . . . . . . . . . 7 4. Direct Question . . . . . . . . . . . . . . . . . . . . . . . 7 5. Motivating Scenario: Pay, Book, Notify . . . . . . . . . . . 8 6. Threat Model . . . . . . . . . . . . . . . . . . . . . . . . 8 7. Goals and Non-Goals . . . . . . . . . . . . . . . . . . . . . 8 8. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. Composite Objects . . . . . . . . . . . . . . . . . . . . . . 9 9.1. Composite CAD . . . . . . . . . . . . . . . . . . . . . . 9 9.2. Child Handles . . . . . . . . . . . . . . . . . . . . . . 10 9.3. Composite Handle . . . . . . . . . . . . . . . . . . . . 11 10. Composite State Machine . . . . . . . . . . . . . . . . . . . 11 11. Prepare, Commit, Abort . . . . . . . . . . . . . . . . . . . 12 11.1. Phase 0: Reconstruct Each Child . . . . . . . . . . . . 13 11.2. Phase 1: Prepare . . . . . . . . . . . . . . . . . . . . 13 11.3. Phase 2: Commit or Abort . . . . . . . . . . . . . . . . 13 12. Join Rules . . . . . . . . . . . . . . . . . . . . . . . . . 14 13. Compensation Is a New Act . . . . . . . . . . . . . . . . . . 15 14. Coordinator Rules . . . . . . . . . . . . . . . . . . . . . . 15 15. Timeouts, Crash, and Child CAS Abort . . . . . . . . . . . . 16 16. Formal Join . . . . . . . . . . . . . . . . . . . . . . . . . 18 17. Safety, Closure, and Termination . . . . . . . . . . . . . . 19 17.1. Decision-Log Axioms . . . . . . . . . . . . . . . . . . 19 17.2. Child Action Invariants . . . . . . . . . . . . . . . . 20 17.3. No-Split Theorem . . . . . . . . . . . . . . . . . . . . 20 17.4. Closure Theorem . . . . . . . . . . . . . . . . . . . . 21 17.5. Termination Bounds . . . . . . . . . . . . . . . . . . . 21 17.6. Finality Point and Currentness . . . . . . . . . . . . . 22 17.7. Compensation Is Distinct from C . . . . . . . . . . . . 22 18. Illustrative Pseudocode . . . . . . . . . . . . . . . . . . . 22 19. Composition with Existing Tools . . . . . . . . . . . . . . . 23 20. Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . 24 21. Anticipated Criticisms . . . . . . . . . . . . . . . . . . . 24 21.1. Objection: Saga Plus Handle Is Enough . . . . . . . . . 24 21.2. Objection: Prepare Across N Sinks Is a Latency Tax . . . 25 21.3. Objection: Each Child Cannot Reconstruct a Unified CAD . . . . . . . . . . . . . . . . . . . . . . . . . . 25 21.4. What Would Settle the Argument . . . . . . . . . . . . . 26 22. Industrial Relevance and Public-Roadmap Alignment . . . . . . 26 Das Expires 20 March 2027 [Page 3] Internet-Draft Composite Execution Finality September 2026 23. Questions to the IETF Community . . . . . . . . . . . . . . . 26 24. Potential IETF Discussion Venues . . . . . . . . . . . . . . 27 24.1. DISPATCH . . . . . . . . . . . . . . . . . . . . . . . . 27 24.2. OAuth . . . . . . . . . . . . . . . . . . . . . . . . . 27 24.3. WIMSE . . . . . . . . . . . . . . . . . . . . . . . . . 28 24.4. RATS . . . . . . . . . . . . . . . . . . . . . . . . . . 28 24.5. HTTPAPI . . . . . . . . . . . . . . . . . . . . . . . . 28 24.6. SCITT . . . . . . . . . . . . . . . . . . . . . . . . . 28 24.7. SAAG . . . . . . . . . . . . . . . . . . . . . . . . . . 28 24.8. No Presumed Home . . . . . . . . . . . . . . . . . . . . 28 25. Relationship to Other Execution-Finality Internet-Drafts . . 28 26. Security Considerations . . . . . . . . . . . . . . . . . . . 29 27. Privacy Considerations . . . . . . . . . . . . . . . . . . . 30 28. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 29. Criticism, Corrections, and Review Invited . . . . . . . . . 30 30. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 30 31. Normative References . . . . . . . . . . . . . . . . . . . . 30 32. Informative References . . . . . . . . . . . . . . . . . . . 31 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 32 1. What This Version (-01) Contains 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]. 1.1. Contents of -01 * Problem of split reality (one child posts, another rejects) after a locally correct handle. * Composite CAD, child handles bound to composite_id, coordinator rules. * Prepare/commit/abort, join rules, and the mitigation profile for no_prepare sinks. * 2PC timeout incompatibility resolved by a compare-and-swap Composite Decision Log: child CAS ABORT on an empty log, HOLD only when the log is unreachable, EF-047 for a discovered split. * Formal join identities and pointer to the handle-draft hash / TLA+ embedding. * Anticipated criticisms (saga plus handle, latency, reconstruction) and abstract hints. Das Expires 20 March 2027 [Page 4] Internet-Draft Composite Execution Finality September 2026 * Industrial disclaimer, community questions, and IETF venue mapping. 1.2. Changes from -00 * Document name and series info updated to -01. * Abstract names saga, performance, and reconstruction objections, and states the decision-log rule. * Added the Composite Decision Log: durable, linearizable, written only by compare-and-swap (first writer wins). The coordinator wins the log before sending any decision. * A prepared child whose reservation timer expires consults the log: COMMIT commits, ABORT releases, an empty log allows the child to CAS ABORT, and an unreachable log leads to HOLD (EF-048). This removes the -00 partial-commit path and prevents indefinite blocking when the coordinator dies before deciding. * Coordinator abort that loses the CAS to COMMIT re-drives commit instead of aborting. * Coordinator re-checks EH_C currentness immediately before writing COMMIT. * After COMMIT is recorded, child commits are retried to a terminal state; only a child that cannot post yields COMPENSATING with EF- 047. * The same rule is applied consistently in the state machine, Phase 2, coordinator rules, timeouts, formal join, PreventionWellFormed, pseudocode, profiles, questions, venues, security, and IANA sections. * ABORTED includes a deliberate coordinator abort, always via the log. * Partial commit uses EF-047, not EF-044. * Security Considerations adds decision-log integrity and availability as trusted computing base, and child-forced abort as a liveness (not safety) attack. * Family references aligned to current titles, revisions, and Datatracker URLs; handle and registries cited as -01. Das Expires 20 March 2027 [Page 5] Internet-Draft Composite Execution Finality September 2026 * Split(C,t) refined so that the normal in-progress window after COMMIT is Closing(C,t) and COMMIT_DECIDED, not COMPENSATING. * Child handles bind composite_digest = d(C), a digest over the sorted child list, not only composite_id. * Added Safety, Closure, and Termination: decision-log axioms, child action invariants, No-Split theorem with proof, Closure theorem with its separate assumptions, termination bounds, the finality point and currentness condition, and compensation identities. 2. Introduction 2.1. Vulnerability: One Intent, Split Reality 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 Figure 1: Child S1 commits; child S2 never becomes effective 2.2. Existing Mechanisms Already Coordinate Steps 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 Expires 20 March 2027 [Page 6] Internet-Draft Composite Execution Finality September 2026 2.3. Residual Gap After a Single-Sink Handle [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. 2.4. What This Document Introduces * Composite CAD with an ordered, explicit child list and a composite Act Digest. * One child Execution Handle per required sink, all bound to the same composite id. * Prepare / commit / abort on consume-state, with fail-closed defaults. * A coordinator role that cannot substitute for child sinks. * Compensation as a new Candidate Act, not a hidden reverse of the original handle. 3. Conventions and Requirements Language 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. 4. Direct Question 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. Das Expires 20 March 2027 [Page 7] Internet-Draft Composite Execution Finality September 2026 5. Motivating Scenario: Pay, Book, Notify 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 Figure 2: Why retry-later is a different Candidate Act 6. Threat Model The attacker need not forge handles. Relevant failures: * Child reordering so an optional notify is treated as required, or the reverse. * Coordinator crash after S1 prepare and before S2 prepare. * S2 commit of a mutated child CAD under the same composite id. * Calling compensation on S1 without a new handle. * Declaring success from the coordinator receipt while a required child is still PENDING. * Using a saga log as proof that no child effect exists. 7. Goals and Non-Goals 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. Das Expires 20 March 2027 [Page 8] Internet-Draft Composite Execution Finality September 2026 8. Terminology *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. 9. Composite Objects 9.1. Composite CAD A composite CAD is a CAD whose consequence_class and coordinator sink_type are COMPOSITE [DAS-REG]. It MUST list children explicitly. Das Expires 20 March 2027 [Page 9] Internet-Draft Composite Execution Finality September 2026 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). 9.2. Child Handles 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 Das Expires 20 March 2027 [Page 10] Internet-Draft Composite Execution Finality September 2026 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]. 9.3. Composite Handle 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. 10. Composite State Machine Das Expires 20 March 2027 [Page 11] Internet-Draft Composite Execution Finality September 2026 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 Figure 3: States of C, distinct from child sink states 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. 11. Prepare, Commit, Abort Das Expires 20 March 2027 [Page 12] Internet-Draft Composite Execution Finality September 2026 11.1. Phase 0: Reconstruct Each Child 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. 11.2. Phase 1: Prepare 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. 11.3. Phase 2: Commit or Abort Das Expires 20 March 2027 [Page 13] Internet-Draft Composite Execution Finality September 2026 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. 12. Join Rules +===================+====================+========================+ | Rule | C EFFECTUATED when | Prevention claim | +===================+====================+========================+ | ALL_REQUIRED | every required | Yes, if every required | | | child EFFECTUATED | sink supports prepare | +-------------------+--------------------+------------------------+ Das Expires 20 March 2027 [Page 14] Internet-Draft Composite Execution Finality September 2026 | ALL_THEN_OPTIONAL | required set | Only over the required | | | EFFECTUATED; | set | | | optional attempted | | +-------------------+--------------------+------------------------+ | QUORUM(k) | any k children | No for high- | | | | consequence classes | +-------------------+--------------------+------------------------+ | BEST_EFFORT | coordinator tried | Never | +-------------------+--------------------+------------------------+ Table 1: Join rules and whether prevention may be claimed 13. Compensation Is a New Act 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 Figure 4: Compensation does not reuse the original child handle 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. 14. Coordinator Rules * The coordinator MUST NOT post a child effect itself unless it is that child's sink. * The coordinator MUST win 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. Das Expires 20 March 2027 [Page 15] Internet-Draft Composite Execution Finality September 2026 * After crash, the coordinator MUST read the CDL first, then query child receipts; it MUST NOT assume commit or abort. If the CDL records COMMIT, it MUST re-drive commit to every required child not yet EFFECTUATED. If the CDL is empty, it MAY write ABORT. * A coordinator whose abort CAS loses to COMMIT MUST re-drive commit and MUST NOT send abort. * A coordinator receipt without child receipts is not evidence that C effectuated. * The coordinator SHOULD be identifiable as sink type COMPOSITE in the registry sense only: it joins, it does not replace SETTLEMENT or ACTUATION. 15. Timeouts, Crash, and Child CAS Abort Classic two-phase commit is blocking. The following two rules cannot both hold in a prevention profile: 1. A PREPARED child whose reserve TTL expires aborts locally without asking anyone. 2. After the coordinator has decided COMMIT, no required child may abort. 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. Das Expires 20 March 2027 [Page 16] Internet-Draft Composite Execution Finality September 2026 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. Das Expires 20 March 2027 [Page 17] Internet-Draft Composite Execution Finality September 2026 16. Formal Join 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 Das Expires 20 March 2027 [Page 18] Internet-Draft Composite Execution Finality September 2026 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 17. Safety, Closure, and Termination 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. 17.1. Decision-Log Axioms 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. Das Expires 20 March 2027 [Page 19] Internet-Draft Composite Execution Finality September 2026 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 17.2. Child Action Invariants 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) 17.3. No-Split Theorem 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 Das Expires 20 March 2027 [Page 20] Internet-Draft Composite Execution Finality September 2026 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. 17.4. Closure Theorem 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. 17.5. Termination Bounds 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) Das Expires 20 March 2027 [Page 21] Internet-Draft Composite Execution Finality September 2026 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. 17.6. Finality Point and Currentness 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 17.7. Compensation Is Distinct from C 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 18. Illustrative Pseudocode 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: Das Expires 20 March 2027 [Page 22] Internet-Draft Composite Execution Finality September 2026 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) 19. Composition with Existing Tools +===============+==================+=========================+ | Existing tool | Supplies | Still required | +===============+==================+=========================+ | XA / 2PC | Prepare/commit | Child Act Digest + | | | wire to RMs | handle bind | +---------------+------------------+-------------------------+ | Saga / TCC | Forward + | Compensation as new | | | compensate graph | handle; no silent undo | Das Expires 20 March 2027 [Page 23] Internet-Draft Composite Execution Finality September 2026 +---------------+------------------+-------------------------+ | Outbox / | Ordered jobs, | Retries are new | | workflow | retries | attempts, not C success | +---------------+------------------+-------------------------+ | SCITT | Logged composite | Log is not child commit | | | receipt | | +---------------+------------------+-------------------------+ | Single-sink | Local authority | This join | | handle | | | +---------------+------------------+-------------------------+ Table 2: What existing coordinators supply versus what is still required 20. Profiles 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. 21. Anticipated Criticisms 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. 21.1. Objection: Saga Plus Handle Is Enough 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: * the saga logs SUCCESS after a required child posts and another required child rejects; * compensation reuses the original child handle instead of a new reverse act; Das Expires 20 March 2027 [Page 24] Internet-Draft Composite Execution Finality September 2026 * a no_prepare child (mail, many MCP tools) is treated as if 2PC applied; * the coordinator receipt is taken as proof that settlement occurred. 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. 21.2. Objection: Prepare Across N Sinks Is a Latency Tax 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. 21.3. Objection: Each Child Cannot Reconstruct a Unified CAD 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. Das Expires 20 March 2027 [Page 25] Internet-Draft Composite Execution Finality September 2026 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. 21.4. What Would Settle the Argument 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. 22. Industrial Relevance and Public-Roadmap Alignment 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. 23. Questions to the IETF Community 1. Is composite finality a separate document, or a section of the handle draft? 2. Is ALL_REQUIRED the only join rule worth specifying? 3. Must every prevention-profile child support prepare, or is "post last no_prepare sink" an acceptable prevention trick? Das Expires 20 March 2027 [Page 26] Internet-Draft Composite Execution Finality September 2026 4. Is child compare-and-swap of ABORT into an empty decision log the right reservation-timer default, with HOLD only when the log is unreachable? 5. For sinks where a held reservation is itself harmful, should the profile define a maximum HOLD duration that ends in an operator decision written through the log? 6. Should the Composite Decision Log be a named wire object with a media type, or remain an abstract linearizable register? 7. Is compensation in scope here or a later draft? 8. How should composite receipts nest child receipts without becoming a new transparency protocol? 9. What prior art (XA, saga, TCC, TN, workflow) already closes this if child handles are added as resources? 10. Should optional children be forbidden in v1 so that notify-later is always a new act? 11. Which venue: DISPATCH, then none until handle lands? 12. If a saga profile already forbids success-without-child-receipts and silent reuse of a consumed handle, should this draft shrink to CAD fields only? 13. Is authorize/capture on existing rails accepted as prepare/ commit, or must the wire names change? 24. Potential IETF Discussion Venues This document does not claim that any named group should adopt the work. 24.1. DISPATCH Natural first stop: the work spans payments, HTTP APIs, and agents. 24.2. OAuth Relevant only if child handles are token profiles. OAuth should not own actuation join. Das Expires 20 March 2027 [Page 27] Internet-Draft Composite Execution Finality September 2026 24.3. WIMSE Relevant if child actors are workloads on different hops. Workload identity is not composite join. 24.4. RATS Relevant if a child CAD includes environment currentness. Attestation is not prepare. 24.5. HTTPAPI Relevant to coordinator HTTP resources and problem+json mapping of EF-047 / COMPENSATING and EF-048 / HOLD. 24.6. SCITT Relevant to logging composite receipts. Not the commit protocol. 24.7. SAAG Useful for whether all-or-none across administrative domains is in scope for the IETF at all. 24.8. No Presumed Home Individual -00. No IANA request in this revision beyond codes already reserved in [DAS-REG]. 25. Relationship to Other Execution-Finality Internet-Drafts This draft sits above the handle and the registries. It does not replace predicate or domain drafts. Das Expires 20 March 2027 [Page 28] Internet-Draft Composite Execution Finality September 2026 DAS-PROTOCOL architecture DAS-HANDLE authority at ONE sink DAS-REG COMPOSITE class/type, EF-047 PARTIAL_COMMIT, EF-048 DECISION_LOG_UNREACHABLE this document join of N handle-using sinks DAS-PATH every child path must still be covered DAS-STATE generations still current at commit DAS-REVOCATION a child handle can be withdrawn before commit DAS-JURISDICTION each child JEC may differ; join must see that DAS-PURPOSE live purpose of C and of each child DAS-AGENTIC tool chain is often the composite proposer Still not this draft: delegation warrant break-glass override See [DAS-HANDLE], [DAS-REG], [DAS-PROTOCOL], [DAS-PATH], [DAS-STATE], [DAS-REVOCATION], [DAS-JURISDICTION], [DAS-PURPOSE], and [DAS-AGENTIC]. 26. Security Considerations 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. Das Expires 20 March 2027 [Page 29] Internet-Draft Composite Execution Finality September 2026 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. 27. Privacy Considerations 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. 28. IANA Considerations 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. 29. Criticism, Corrections, and Review Invited 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. 30. Conclusion 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 31. Normative References Das Expires 20 March 2027 [Page 30] Internet-Draft Composite Execution Finality September 2026 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, May 2017, . 32. Informative References [DAS-AGENTIC] Das, S., "Tool Selection Is Not Execution: Finality for Agentic Tool Dispatch in High-Risk AI Systems", Work in Progress, Internet-Draft, draft-das-agentic-execution- finality-02, September 2026, . [DAS-HANDLE] Das, S., "Possession Is Not Authority: Execution Handle, Sink Verification, Atomic Consumption, and Finality Receipt", Work in Progress, Internet-Draft, draft-das- execution-handle-01, September 2026, . [DAS-JURISDICTION] Das, S., "Authorized Here, Not Authorized There: Jurisdiction-Bound Execution Finality for Cross-Border and Sovereign Systems", Work in Progress, Internet-Draft, draft-das-jurisdiction-bound-execution-finality-00, September 2026, . [DAS-PATH] Das, S., "When the Gate Can Be Bypassed: Consequence-Path Completeness for Execution Finality", Work in Progress, Internet-Draft, draft-das-consequence-path-completeness- 00, September 2026, . [DAS-PROTOCOL] Das, S., "The Missing Protocol Layer for the Agentic Internet: Computation Is Not Authority", Work in Progress, Internet-Draft, draft-das-execution-finality-protocol- layer-01, September 2026, . Das Expires 20 March 2027 [Page 31] Internet-Draft Composite Execution Finality September 2026 [DAS-PURPOSE] Das, S., "Data-Purpose Laundering Prevention: Execution- Finality for Preventing Cross-Domain Data Reuse", Work in Progress, Internet-Draft, draft-das-purpose-execution- finality-03, September 2026, . [DAS-REG] Das, S., "Illustrative Codes Are Not a Namespace: Registries for Execution-Finality Objects", Work in Progress, Internet-Draft, draft-das-ef-registries-01, September 2026, . [DAS-REVOCATION] Das, S., "Revoked but Still Executable: Closing the Authorization-to-Effect Gap with Finality-Bound Revocation", Work in Progress, Internet-Draft, draft-das- finality-bound-revocation-00, September 2026, . [DAS-STATE] Das, S., "When Valid Authorization Becomes Stale: State and Policy Continuity at the Execution-Finality Boundary", Work in Progress, Internet-Draft, draft-das-state-policy- continuity-finality-00, September 2026, . Author's Address Sangam Das Independent Balasore Odisha India Phone: +91-9861363532 Email: info@sangamdas.com Das Expires 20 March 2027 [Page 32]