fix(actor-runtime): execute or reject the full Effect vocabulary (ARN-179)

[nerdsane]

Fixes ARN-179 ([BUG] Postgres actor-runtime backend silently drops half the Effect vocabulary).

Defect

SpecDrivenActor::apply_effect matched 8 of the 16 temper_jit::table::Effect variants and dropped the other 8 through a _ => tracing::debug! catch-all: ListAppend, ListRemoveAt, IncrementCounterByParam, DecrementCounterByParam, SetCounterFromParam, ScheduleAction, ScheduleAtAction, SpawnEntity. A spec whose transition appends to a list or sets a counter from an action param had that effect silently discarded, so a later guard reading the variable (list_length_min, counter_min) evaluated stale state and mis-gated transitions.

A second, disagreeing copy of the vocabulary decision lived in temper-cli/src/serve/actor_runtime.rs (spec-level effect match) — one instance of the ARN-212 parallel-interpreter drift called out in the issue's enrichment comment.

Fix (root cause)

Single source of truth in the crate, enforced at construction, exhaustive at compile time:

• validate_effect_support (new, temper-actor-runtime/src/spec_actor.rs): exhaustive match over the compiled TransitionTable's effects, called from from_automaton (now Result) and from_ioa. A new Effect variant in temper-jit now fails compilation here instead of being silently dropped.
• Implemented the five param-driven state effects (ListAppend, ListRemoveAt, IncrementCounterByParam, DecrementCounterByParam, SetCounterFromParam), mirroring the canonical executor semantics in temper-server/src/entity_actor/effects.rs (list value keyed by var name, removal index from {var}_index, deltas accept numbers/numeric strings and default to 0, set_counter_from_param requires a non-negative integer).
• Rejected at construction: ScheduleAction/ScheduleAtAction/SpawnEntity (the runtime has no delayed delivery and no per-entity addressing) and Custom trigger effects with no reaction routing (previously a warn-level runtime no-op). apply_effect has no catch-all; construction-rejected variants fail the activation loudly if ever reached.
• Deleted the duplicated CLI effect-vocabulary check; the CLI keeps its serve-specific integration/action-trigger checks.
• ADR-0156 documents the vocabulary policy and the deliberate scoping relative to ARN-212.

TDD

• RED commit 9ddfa464 adds 4 failing regression tests (committed alone; failures documented in the commit message): param effects dropped, list_length_min mis-gating after list_append, schedule/schedule_at/spawn accepted at construction, unrouted trigger accepted at construction.
• GREEN commit makes all 4 pass with the fix above.

DST note: temper-actor-runtime and temper-cli are not simulation-visible crates (no DST suite applies); the exhaustive-match + construction-rejection is the regression barrier for this class.

Provenance note

This crate is the externally-contributed PG actor runtime (ARN-26 / PR #218). The issue itself says "coordinate before changing" — this PR is an arena submission per the ARN-165 non-security queue; routing the merge decision through the contributor remains available to the judge/Rita.

Verification

• cargo test -p temper-actor-runtime --lib — 6/6 (4 new regression tests green)
• cargo test -p temper-cli — 72/72
• cargo fmt --check, git diff --check, cargo clippy -p temper-actor-runtime -p temper-cli -- -D warnings — clean
• Full workspace suite + live local E2E: evidence posted as PR comments below.

Greptile Summary

This PR fixes ARN-179, where SpecDrivenActor::apply_effect silently dropped 8 of the 16 Effect variants via a _ => debug! catch-all, causing list/counter state mutations from param-driven effects to be discarded and guards reading those variables to evaluate stale state.

• New validate_effect_support (exhaustive match over the compiled TransitionTable) is called from from_automaton (now Result) at construction time, making SpecDrivenActor the single source of truth for the Postgres actor runtime's effect vocabulary — a new Effect variant now fails compilation here instead of being silently dropped.
• Implemented ListAppend, ListRemoveAt, IncrementCounterByParam, DecrementCounterByParam, and SetCounterFromParam, mirroring the canonical executor in temper-server/src/entity_actor/effects.rs line-for-line; ScheduleAction, ScheduleAtAction, and SpawnEntity are explicitly rejected at construction with actionable errors.
• Deleted the duplicate effect-vocabulary check from the CLI's validate_actor_runtime_compatible; the CLI retains its integration and action-trigger checks. Four regression tests (RED → GREEN commit sequence) cover each fixed scenario.

Confidence Score: 5/5

Safe to merge. The fix is mechanically straightforward, the new code was verified against the canonical executor line-by-line, and four targeted regression tests confirm both the bug and the fix.

Every changed path is well-covered: exhaustive matches replace the silent catch-all, construction-time rejection replaces runtime drops, and param-driven semantics were confirmed to match the canonical executor in temper-server. No regressions introduced in the CLI; the removed validation block was superseded by the runtime crate's own construction check, which now fires earlier (at serve startup) via the from_ioa call in configure_postgres_actor_runtime.

No files require special attention. effects.rs is the core new file and its logic is a faithful mirror of temper-server/src/entity_actor/effects.rs.

Important Files Changed

Filename	Overview
crates/temper-actor-runtime/src/spec_actor/effects.rs	New file implementing the full Effect vocabulary: exhaustive validate_effect_support (construction-time rejection) and exhaustive apply_effect (no catch-all). Param-driven effects correctly mirror the canonical executor in temper-server/src/entity_actor/effects.rs line-for-line.
crates/temper-actor-runtime/src/spec_actor/mod.rs	Renamed from spec_actor.rs to mod.rs (split into submodules). from_automaton changed from infallible to Result; validate_effect_support wired at construction; params extraction refactored to always produce a serde_json::Value (Null when absent), enabling apply_effect to receive params on every call.
crates/temper-actor-runtime/src/spec_actor/tests.rs	Four new regression tests covering: param-driven effect mutations, list guard mis-gating (the exact ARN-179 scenario), construction rejection of schedule/spawn effects, and construction rejection of unrouted trigger effects. Tests are specific and well-named.
crates/temper-cli/src/serve/actor_runtime.rs	Removes the duplicate effect-vocabulary check from validate_actor_runtime_compatible; retains integration and action-trigger checks. SpecDrivenActor::from_ioa is now the sole vocabulary gate, called with an empty routing map during actor registration at serve startup.
docs/adrs/0156-pg-actor-runtime-effect-vocabulary.md	ADR-0156 documents the vocabulary policy, construction-rejection decision, and deliberate scoping relative to ARN-212. Well-structured and covers alternatives considered.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant CLI as temper-cli
    participant VAC as validate_actor_runtime_compatible
    participant SDA as SpecDrivenActor::from_ioa
    participant VES as validate_effect_support
    participant AE as apply_effect

    CLI->>VAC: collect_actor_runtime_definitions(registry, types)
    VAC-->>CLI: Err if legacy integrations or action triggers

    CLI->>SDA: from_ioa(ioa_source, HashMap::new())
    SDA->>VES: validate_effect_support(table, routing)
    Note over VES: Exhaustive match over all Effect variants
    VES-->>SDA: Err if Schedule/Spawn/unrouted Custom
    SDA-->>CLI: Ok(SpecDrivenActor) or Err

    CLI->>CLI: system.register(actor)

    Note over CLI,AE: At runtime, for each incoming message:
    CLI->>AE: apply_effect(state, effect, params, ctx)
    Note over AE: Exhaustive match — no catch-all
    AE-->>CLI: Ok(()) or ActorError::HandlerFailed

Loading

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sequenceDiagram
    participant CLI as temper-cli
    participant VAC as validate_actor_runtime_compatible
    participant SDA as SpecDrivenActor::from_ioa
    participant VES as validate_effect_support
    participant AE as apply_effect

    CLI->>VAC: collect_actor_runtime_definitions(registry, types)
    VAC-->>CLI: Err if legacy integrations or action triggers

    CLI->>SDA: from_ioa(ioa_source, HashMap::new())
    SDA->>VES: validate_effect_support(table, routing)
    Note over VES: Exhaustive match over all Effect variants
    VES-->>SDA: Err if Schedule/Spawn/unrouted Custom
    SDA-->>CLI: Ok(SpecDrivenActor) or Err

    CLI->>CLI: system.register(actor)

    Note over CLI,AE: At runtime, for each incoming message:
    CLI->>AE: apply_effect(state, effect, params, ctx)
    Note over AE: Exhaustive match — no catch-all
    AE-->>CLI: Ok(()) or ActorError::HandlerFailed

Loading

_{Reviews (1): Last reviewed commit: "refactor(actor-runtime): split spec_acto..." | Re-trigger Greptile}

[nerdsane]

Live local E2E evidence (ARN-179)

Setup: native PostgreSQL 17.8 on localhost:5432; spec dir with Inventory entity exercising every param-driven effect plus a list_length_min guard (inventory.ioa.toml + model.csdl.xml); one binary built at merge-base a28fdb2e ("before"), one at the PR head ("after").

BEFORE (main @ a28fdb2) — capability rejected at startup

$ DATABASE_URL="postgres://seshendranalla@localhost:5432/temper_arn179_before" TEMPER_EVENT_STORE=postgres \
    ./temper-before serve --port 3178 --storage postgres --actor-runtime postgres \
    --actor-backed-type Inventory --specs-dir ./e2e-specs --tenant arn179 --no-observe
Error: tenant arn179 entity Inventory action AddTag uses effect ListAppend { var: "tags" }, which is not yet supported by --actor-runtime postgres
EXIT CODE: 1

(The silent-drop path itself sits behind this CLI wall on main; the RED unit tests in commit 9ddfa464 prove the crate-level drop directly: list_append leaves the list empty and the list_length_min guard then mis-gates Lock.)

AFTER (PR head) — spec accepted, every effect executes, guard gates correctly

Server starts, Inventory passes L0–L3 verification, PG actor runtime scheduler starts:

  [verify] Inventory: [PASS] L0 Symbolic PASSED: 6 guards satisfiable, 1 invariants inductive, 0 unreachable
  [verify] Inventory: [PASS] L1 Model Check PASSED: 9 states explored, all properties hold
  [verify] Inventory: [PASS] L2 Simulation PASSED: 5 seeds, 146 transitions, 0 dropped msgs
  [verify] Inventory: [PASS] L3 Property Tests PASSED: 100 cases, 30 max steps
{"message":"actor scheduler starting","target":"temper_actor_runtime::scheduler"}
Listening on http://0.0.0.0:3179

Live flow (each POST returns the updated actor state):

$ curl -s -X POST -H 'X-Tenant-Id: arn179' -H 'Content-Type: application/json' -d '{"Id":"inv-1"}' http://localhost:3179/tdata/Inventorys
{"@odata.type":"#Inventory","Id":"inv-1","namespace":"arn179/inv-1"}

$ curl -s -X POST ... -d '{"tags":"urgent"}' ".../Inventorys('inv-1')/Temper.InventoryDemo.AddTag"
{"entity_type":"Inventory","entity_id":"inv-1","status":"Active","counters":{"progress":0,"total":0},"booleans":{},"lists":{"tags":["urgent"]},"fields":{"Id":"inv-1","tags":"urgent"}}

$ curl -s -X POST ... -d '{"qty":5}'  .../Temper.InventoryDemo.RecordBatch   → counters: {'progress': 0, 'total': 5}
$ curl -s -X POST ... -d '{"qty":2}'  .../Temper.InventoryDemo.ConsumeBatch  → counters: {'progress': 0, 'total': 3}
$ curl -s -X POST ... -d '{"value":42}' .../Temper.InventoryDemo.SetProgress → counters: {'progress': 42, 'total': 3}
$ curl -s -X POST ... -d '{}' .../Temper.InventoryDemo.Lock                  → status: Locked | lists: {'tags': ['urgent']}

$ curl -s -H 'X-Tenant-Id: arn179' "http://localhost:3179/tdata/Inventorys('inv-1')"
{"entity_type":"Inventory","entity_id":"inv-1","status":"Locked","counters":{"progress":42,"total":3},"booleans":{},"lists":{"tags":["urgent"]},"fields":{"Id":"inv-1","tags":"urgent","qty":2,"value":42},"@odata.context":"$metadata#Inventorys/$entity","@odata.id":"Inventorys('inv-1')"}

The exact mis-gating scenario from the issue — a list_length_min guard reading a list a prior transition appended to — now gates correctly (Lock succeeds only because list_append really appended).

AFTER — unexecutable effects now fail fast at startup with an actionable error

$ ./temper-after serve ... --specs-dir ./e2e-specs-schedule ...   # same spec but with a schedule effect
Error: failed to build actor for Inventory: action "Lock" uses effect type "schedule", which the Postgres actor runtime cannot execute (it has no delayed delivery or per-entity spawning)
EXIT CODE: 1

[nerdsane]

Independent reviewer (Claude Fable 5, dedicated session) — ARN-179 / PR #370

I reviewed this PR with no prior context, from the GitHub diff, the commit history, the E2E evidence comment, and the code at the PR head. I verified the TDD claims and the canonical-semantics mirroring against the running tree.

What I checked and confirmed

• Root cause is fixed correctly, not patched. The silent _ => tracing::debug! catch-all in SpecDrivenActor::apply_effect is gone. Both validate_effect_support (construction) and apply_effect now match all 16 temper_jit::table::Effect variants exhaustively with no catch-all (crates/temper-actor-runtime/src/spec_actor/effects.rs:29-77 and :96-186). I confirmed the enum has exactly 16 variants (crates/temper-jit/src/table/types.rs), so a new variant fails compilation in this crate — that is the durable regression barrier for this class, and it is the right one.
• Construction-time rejection is wired into serve and propagates. from_automaton/from_ioa now return Result and are called at serve time (crates/temper-cli/src/serve/actor_runtime.rs:88), so schedule/schedule_at/spawn specs fail fast with an actionable error rather than mis-executing — matches the E2E evidence.
• Canonical semantics faithfully mirrored. I diffed the new ListAppend, ListRemoveAt, IncrementCounterByParam, DecrementCounterByParam, SetCounterFromParam, and counter_delta_from_params against crates/temper-server/src/entity_actor/effects.rs:478-544, 660-668. They match line-for-line (the only canonical-only bit is the item_count special-casing, which SpecActorState does not have — it keeps items in the counters map, so it stays internally consistent).
• Duplicate vocabulary removed, single source of truth. The disagreeing effect-vocabulary match in temper-cli is deleted; the retained validate_actor_runtime_compatible keeps only its integration/action-trigger serve checks (crates/temper-cli/src/serve/actor_runtime.rs:254-273). This removes one of the two ARN-212 drifting copies, correctly scoped.
• TDD is auditable and real. RED commit 9ddfa464 is committed alone (only the 267-line test addition). I checked that commit out and ran it: the 4 regression tests fail as genuine assertion failures against the parent behavior (list_append leaves the list empty, list_length_min mis-gates Lock to Active, schedule/spawn and unrouted trigger accepted at construction) — not compile errors. At the head the same suite is 6/6 green.
• ADR-0156 is accurate and correctly scoped relative to ARN-212 (docs/adrs/0156-...md); number is unique. git diff --check clean; no ADR collision.

Observation (non-blocking, no action required)

The serve path constructs actors with an empty routing map (from_ioa(&definition.ioa_source, HashMap::new()), pre-existing), so the routed-Custom-accept branch of validate_effect_support is not reachable via CLI serve — any trigger effect spec is rejected there (either by the retained action.triggers check or by empty-routing construction). That is consistent with reactions being unsupported at serve today and is not a regression: the old CLI effect loop also rejected trigger effects. The routing-aware branch is forward-looking and correct; flagging only so the scoping is on the record.

Verification I ran

• cargo test -p temper-actor-runtime --lib at RED 9ddfa464: 4 failing (assertion failures, as documented); at head: 6/6 green.
• Line-by-line compare of param-effect semantics vs temper-server canonical executor: identical.
• git diff --check: clean; ADR number unique.

No findings at any severity. I would ship this.

Verdict: PASS

[nerdsane]

@greptile review

[nerdsane]

ARENA SHIPPABLE · Claude Code (Fable 5) · 2026-07-12 13:29 PDT

Receipts:

• CI (fully green): https://github.com/nerdsane/temper/actions/runs/29206165138 — Compile & Lint, workspace Tests, all DST/Platform shards, Integrity & DST Patterns, Spec Verification L0–L3, Verification Contract, Instrumentation Hygiene.
• Dedicated same-model reviewer PASS (posted before Greptile was requested): fix(actor-runtime): execute or reject the full Effect vocabulary (ARN-179) #370 (comment) — zero findings; reviewer independently re-ran the RED commit and confirmed genuine assertion failures.
• Greptile: requested at fix(actor-runtime): execute or reject the full Effect vocabulary (ARN-179) #370 (comment) (19:51:53Z, after the reviewer PASS at 19:51:06Z). Result: check success — "5 files reviewed, 0 comments added" (no comment/review object was posted by the bot; the check-run output is the receipt).
• Live local E2E evidence (before/after, commands + output): fix(actor-runtime): execute or reject the full Effect vocabulary (ARN-179) #370 (comment)
• TDD history: RED 9ddfa46 (4 failing regression tests, committed alone) → GREEN e32dd67 (fix + ADR-0156) → 1b169ce (500-line-rule module split).
• Local gates: pre-push hook ALL GATES PASSED (rustfmt, workspace clippy -D warnings, readability ratchet, full workspace test suite); pre-commit code-review + DST-review markers written by reviewer agents.

Notes for the judge: Linear MCP token expired this session — ARENA START (10:28 PDT) is recorded on the master status board (M94) and in this PR instead of on ARN-179; will backfill when Linear reconnects. This crate is the externally-contributed PG actor runtime (ARN-26) — merge routing through the contributor remains available.