rose-ash/plans/fed-sx-milestone-1.md

fed-sx Milestone 1 — Kernel + Registries + Pin Smoke Test

Concrete implementation plan for the smallest fed-sx that proves the architecture works end-to-end. Reference: plans/fed-sx-design.md. Prerequisite: Erlang-on-SX Phases 7 (hot reload) + 8 (FFI BIFs).

Goal

Ship a single-instance, single-actor fed-sx server that:

1. Boots from a verified genesis bundle.
2. Accepts and durably appends signed activities via POST /activity.
3. Folds them into projections in real time.
4. Serves AP-standard endpoints (actor, outbox, artifacts, capabilities).
5. Demonstrates two extensibility proof-points end-to-end with zero kernel code changes between definition and use:
   • Verb extensibility (§5 meta-level): publish DefineActivity{Pin} + DefineProjection{pin-state}, then publish a Pin activity, observe it validated and projected.
   • Reactive application extensibility (§§18-19): publish DefineSubscription{Topic} + Subscribe{topic: smoketest} + DefineTrigger{when: that subscription, then: publish TestEcho}, then publish a tagged Note, observe the subscription match, the trigger fire, and the derived activity appear in the outbox.

Federation, multi-actor, advanced verbs, IPFS, browser UI, operator dashboard are explicitly v2.

Non-goals (what milestone 1 deliberately does NOT do)

• Federation. No POST /inbox from peers, no Follow, no delivery queue, no webfinger discovery flow. Single instance only.
• Multi-actor. Single domain actor (acct:next@next.rose-ash.com).
• IPFS / S3 storage backends. Files on disk only.
• Advanced verbs. No Endorse, Supersede, Test, Build, Compose, Note, Announce. Only the four bootstrap verbs (Create, Update, Delete) plus a defined-from-the-log Pin for the smoke test. (Announce deferred — no use case until federation exists.)
• Browser UI. Curl-shaped API only.
• Operator dashboard, quarantine UX. Logs only.
• Performance work. Functional correctness first; perf when measured.
• Cross-host conformance test corpus. Only the OCaml/Erlang-on-SX host runs fed-sx in v1; conformance suite for other hosts is v2.

Architecture summary

                          POST /activity
                                │
                                ▼
                  ┌──────────────────────────┐
                  │ HTTP server (Erlang-on-SX)│
                  └─────────────┬─────────────┘
                                │
                  ┌─────────────▼──────────────┐
                  │ Validation pipeline driver  │
                  │ (envelope→sig→schema→...)   │
                  └─────────────┬──────────────┘
                                │
                  ┌─────────────▼──────────────┐
                  │ Log append (JSONL segment)  │  ← canonical
                  └─────────────┬──────────────┘
                                │
                  ┌─────────────▼──────────────┐
                  │ Projection workers          │  ← gen_server per
                  │ (fold scheduler)            │     projection
                  └─────────────────────────────┘
                                │
                                ▼
                       Projection state
                       (queryable via HTTP)

Native primitives (Erlang-on-SX BIFs from Phase 8):
  crypto:* cid:* fs:* http:* sqlite:*

Genesis bundle (binary-embedded SX):
  activity-types  object-types  projections
  validators      codecs        sig-suites

Build order

Eight steps in dependency order. Each step has concrete deliverables, testable in isolation, and a clear acceptance check.

Step	Title	Depends on
1	Repo skeleton + canonical CID computation	Phase 8 (cid BIFs)
2	Activity envelope + signature verify	Phase 8 (crypto BIFs)
3	JSONL log + sequence numbers	Phase 8 (fs BIFs)
4	Genesis bundle (SX sources + bundling + CID verification)	Step 1
5	Registry mechanism + bootstrap-projection dispatch	Steps 2, 4
6	Validation pipeline driver + POST /activity	Steps 2, 3, 5
7	Projection scheduler (gen_server per projection)	Steps 5, 6
8	HTTP server, AP endpoints, projection queries	Steps 6, 7
9	Smoke tests (Pin verb + reactive application)	Steps 1-8

---

Step 1 — Repo skeleton + canonical CID

Deliverables:

next/
├── README.md                         # what this is
├── kernel/                           # Erlang-on-SX
│   └── (empty for now)
├── genesis/                          # core SX bootstrap definitions
│   └── (empty for now)
├── tests/                            # smoke test scripts
│   └── (empty for now)
└── data/                             # gitignored runtime state
    ├── log/
    ├── objects/
    ├── snapshots/
    ├── indexes/
    └── keys/

Plus one Erlang-on-SX module:

% next/kernel/cid.erl
-module(cid).
-export([from_sx/1, to_string/1, from_string/1, equals/2]).

from_sx(SxValue) ->
    Cbor = cid:cbor_encode(canonicalize_sx(SxValue)),
    Hash = crypto:sha2_256(Cbor),
    cid:from_bytes(<<"raw">>, Hash).      % defaults to dag-cbor codec

canonicalize_sx(V) -> ...                  % sorts dict keys, normalizes strings

Tests:

• Same SX value → same CID across multiple invocations.
• Different SX values → different CIDs.
• Whitespace/comment differences in source → identical CIDs (parsed AST identical).
• Reordered dict keys → identical CIDs (sorted-key canonicalization).
• Cross-host parity (just OCaml host for v1, but write the test so adding hosts is mechanical).

Acceptance: bash next/tests/cid.sh passes 10+ cases.

---

Step 2 — Activity envelope + signature verify

Deliverables:

% next/kernel/envelope.erl
-module(envelope).
-export([validate_shape/1, canonical_bytes/1, verify_signature/2]).

% Envelope shape per design §3.1:
%   #{id, type, actor, published, to, cc, audience_extras,
%     object | target | origin | result,
%     capabilities_required, proofs, signature}
validate_shape(Activity) -> ok | {error, Reason}.

canonical_bytes(Activity) ->
    % Strip signature, canonicalize via dag-cbor, return bytes for sig coverage
    Stripped = maps:remove(signature, Activity),
    cid:cbor_encode(canonicalize_for_sig(Stripped)).

verify_signature(Activity, ActorState) ->
    % Time-aware: find key with id == sig.key_id that was active at published
    % Per design §9.6
    ...

Tests:

• Envelope shape: required fields present (id, type, actor, published, signature)
• Envelope shape: type is a known activity-type or unknown-but-string
• Envelope shape: signature has key_id, algorithm, value
• Sig verify: valid RSA-SHA256 signature against published key → ok
• Sig verify: valid Ed25519 signature → ok
• Sig verify: tampered envelope → fail
• Sig verify: key superseded before activity timestamp → fail
• Sig verify: key superseded after activity timestamp → ok (historical valid)

Acceptance: bash next/tests/envelope.sh passes 15+ cases.

---

Step 3 — JSONL log + sequence numbers

Deliverables:

% next/kernel/log.erl
-module(log).
-export([open/1, append/2, read_segment/2, tip/1, replay/3]).

% Per design §15.2: per-actor outbox, segments cap ~64MB,
% format = JSONL (one canonical JSON-LD activity per line)

open(ActorId) ->
    BasePath = log_path_for_actor(ActorId),
    fs:mkdir_p(BasePath),
    {ok, #{base => BasePath, current => current_segment(BasePath), seq => next_seq(BasePath)}}.

append(LogState, Activity) ->
    Json = jsonld:encode(Activity),
    Path = current_segment_path(LogState),
    Line = <<Json/binary, "\n">>,
    fs:append_file(Path, Line),
    NewSeq = LogState#{seq := LogState.seq + 1},
    rotate_if_needed(NewSeq).

% replay/3 calls Fun(Activity, Acc) for every activity in chronological order
replay(LogState, InitAcc, Fun) -> ...

Tests:

• Append + read back gives identical activity (round-trip).
• Sequence numbers monotonic and gap-free per actor.
• Segment rotation at size threshold.
• Replay visits all activities in append order across multiple segments.
• Restart preserves tip pointer (seq number resumes correctly).
• Concurrent appends (using gen_server-mediated access) are serialized correctly.

Acceptance: bash next/tests/log.sh passes 10+ cases.

---

Step 4 — Genesis bundle

Deliverables:

Genesis bundle SX sources (per design §12.2). Each is a small SX file authored by hand for the bootstrap set:

next/genesis/
├── manifest.sx                       # bundle root: lists all definitions
├── activity-types/
│   ├── create.sx                     # DefineActivity{name: "Create", ...}
│   ├── update.sx
│   └── delete.sx
├── object-types/
│   ├── sx-artifact.sx
│   ├── note.sx
│   ├── tombstone.sx
│   ├── define-activity.sx            # DefineObject for the Define* meta types
│   ├── define-object.sx
│   ├── define-projection.sx
│   ├── define-validator.sx
│   ├── define-codec.sx
│   ├── define-sig-suite.sx
│   └── snapshot.sx
├── projections/
│   ├── activity-log.sx               # identity projection
│   ├── by-type.sx
│   ├── by-actor.sx
│   ├── by-object.sx
│   ├── actor-state.sx
│   ├── define-registry.sx            # the chicken-and-egg projection
│   └── audience-graph.sx
├── validators/
│   ├── envelope-shape.sx
│   ├── signature.sx
│   └── type-schema.sx
├── codecs/
│   ├── dag-cbor.sx                   # delegates to cid:cbor_encode/decode BIFs
│   ├── raw.sx
│   └── dag-json.sx
├── sig-suites/
│   ├── rsa-sha256-2018.sx
│   └── ed25519-2020.sx
└── audience/
    ├── public.sx
    ├── followers.sx
    └── direct.sx

Plus a build-time bundler:

% next/kernel/bootstrap.erl
-module(bootstrap).
-export([build_genesis/1, verify_genesis/1, load_genesis/1]).

build_genesis(SourceDir) ->
    % Walk SourceDir, parse each .sx file, build a single dag-cbor bundle,
    % compute its CID, write bundle.cbor + CID to data/genesis/
    ...

verify_genesis(BundlePath) ->
    % Compute CID of the bundle as loaded; compare to expected (hardcoded
    % in the kernel binary). Mismatch → halt.
    ...

load_genesis(BundlePath) ->
    % Parse the bundle, register all definitions in the in-memory registry
    ...

Tests:

• All genesis SX files parse cleanly.
• Bundle CID is deterministic (rebuild same sources → same CID).
• Bundle reload reproduces the exact same registry state.
• Tampered bundle → verify_genesis returns {error, cid_mismatch}.

Acceptance: bash next/tests/bootstrap.sh passes; next/data/genesis/bundle.cbor created with a known stable CID.

---

Step 5 — Registry mechanism + bootstrap dispatch

Deliverables:

Registries are gen_servers, one per kind, each holding the active version map:

% next/kernel/registry.erl
-module(registry).
-behaviour(gen_server).
-export([start_link/0, lookup/2, register/3, list/1]).
% Internal state:
%   #{activity_types => #{Name => #{cid, schema_fn, semantics_fn, supersedes}},
%     object_types   => ...,
%     projections    => ...,
%     validators     => ...,
%     codecs         => ...,
%     sig_suites     => ...,
%     ...}

lookup(Kind, Name) -> {ok, Entry} | {error, not_found}.
register(Kind, Name, Entry) -> ok | {error, Reason}.
list(Kind) -> [#{name, cid}].

The define-registry projection's fold updates this gen_server's state when new Define* activities arrive. (Bootstrapping circle resolved: at startup, bootstrap:load_genesis/1 populates the registry directly; from then on, the projection fold maintains it.)

Tests:

• After genesis load, registry:list(activity_types) returns Create/Update/Delete.
• registry:lookup(activity_types, "Create") returns the schema and semantics.
• A new DefineActivity{name: "Pin"} activity (synthesised, hand-signed for the test) routes through the projection fold, ends up in the registry.
• Lookup never caches across activities (verified by introducing a new definition mid-test and confirming the next lookup sees it).

Acceptance: bash next/tests/registry.sh passes 10+ cases.

---

Step 6 — Validation pipeline + POST /activity

Deliverables:

% next/kernel/pipeline.erl
-module(pipeline).
-export([validate_inbound/1, validate_outbound/1]).

% Per design §14, run stages in order, halt on first failure.
validate_inbound(Activity) ->
    Stages = [
        fun stage_envelope/1,
        fun stage_signature/1,
        fun stage_replay/1,
        fun stage_audience/1,
        fun stage_activity_schema/1,
        fun stage_object_schema/1,
        fun stage_content_validators/1,
        fun stage_capabilities/1,
        fun stage_trust/1
    ],
    run_stages(Activity, Stages).

validate_outbound(Activity) ->
    % Subset of inbound stages (no replay, no trust check; auth done at HTTP layer)
    ...

% next/kernel/outbox.erl
-module(outbox).
-export([publish/2]).

publish(ActorId, ActivityRequest) ->
    Activity = construct_envelope(ActorId, ActivityRequest),
    Signed = sig:sign(Activity, ActorId),
    case pipeline:validate_outbound(Signed) of
        ok ->
            log:append(actor_log(ActorId), Signed),
            projection:async_fold(Signed),
            {ok, #{cid => cid:from_sx(Signed),
                   ap_id => maps:get(id, Signed)}};
        {error, Reason} ->
            {error, Reason}
    end.

Tests:

• Valid activity through full pipeline → appended to log.
• Bad envelope → 400, not in log.
• Bad signature → 401, not in log.
• Replayed activity → 200 duplicate, not re-appended.
• Schema violation (e.g. Create with no object) → 422.
• Activity logged before projection completes (async).

Acceptance: bash next/tests/pipeline.sh passes 15+ cases.

---

Step 7 — Projection scheduler

Deliverables:

% next/kernel/projection.erl
-module(projection).
-export([start_link/1, async_fold/1, query/2, snapshot/1]).
-behaviour(gen_server).

% One gen_server per active projection. State:
%   #{cid, name, fold_fn, current_state, log_tip,
%     snapshot_dir, last_snapshot_at}

% async_fold/1 broadcasts a new activity to every projection gen_server;
% each folds it into its own state. Failures (gas, sandbox violation)
% tag the activity but don't affect log durability.

% query/2 returns current state (or state-as-of)
% snapshot/1 forces a snapshot now (also runs periodically)

% next/kernel/sandbox.erl
-module(sandbox).
-export([eval_pure/2, eval_crypto/2, eval_effectful/3]).

% eval_pure runs an SX function in pure mode: no IO platform, gas budget,
% deterministic. Used by projection folds, validators, audience predicates.
% Wrapper over the SX runtime evaluator with a stripped platform.

Tests:

• New activity → all projections fold it concurrently.
• Projection fold completes within gas budget.
• Gas-exhausting fold → activity tagged, projection state unchanged, no kernel crash.
• Sandbox violation (fold tries IO) → same handling.
• Snapshot create + reload → state matches.
• Snapshot CID stable across kernel restarts.

Acceptance: bash next/tests/projection.sh passes 15+ cases.

---

Step 8 — HTTP server + endpoints

Deliverables:

Core endpoints (per design §16.1):

GET  /actors/<id>                     # actor doc
GET  /actors/<id>/outbox              # OrderedCollection
GET  /actors/<id>/outbox?page=true    # OrderedCollectionPage
POST /activity                        # publish (auth: bearer token)
GET  /artifacts/<cid>                 # CID-addressed artifact
GET  /artifacts/<cid>/raw
GET  /projections                     # list of projections
GET  /projections/<name>              # full state
GET  /projections/<name>?at=<ts>      # time-travel
GET  /projections/<name>/<key>        # indexed lookup
GET  /define-registry
GET  /.well-known/sx-capabilities
GET  /.well-known/webfinger

% next/kernel/http_server.erl
-module(http_server).
-export([start/1, route/1]).

start(Port) ->
    http:listen(Port, fun ?MODULE:route/1).

route(Request) -> {Status, Headers, Body}.

Content negotiation per Accept:

• application/activity+json (default)
• application/cbor (dag-cbor)
• application/json (compact, no @context expansion)
• application/sx

Auth on POST /activity: bearer token from env var NEXT_PUBLISH_TOKEN.

Tests:

• Each endpoint returns expected shape for known artifact.
• Content negotiation: same artifact in 4 representations.
• 404 for unknown artifact CID.
• 401 for POST /activity without token.
• Pagination: outbox with > 50 activities returns OrderedCollectionPage.

Acceptance: bash next/tests/http.sh passes 20+ cases.

---

Step 9 — Smoke tests

The proof points. Two end-to-end smoke tests demonstrate, between them, that fed-sx is genuinely a substrate for distributed reactive applications expressed as data — not a system you extend by writing kernel code.

• 9a — Pin smoke test (next/tests/smoke_pin.sh) — verb extensibility: defining a new activity type and projection at runtime via Define* artifacts. Verifies the meta-level (§5).
• 9b — Reactive application smoke test (next/tests/smoke_app.sh) — application extensibility: defining a new subscription type, subscribing, registering a trigger, and observing the full reactive loop fire end-to-end without kernel code changes. Verifies §§18-19.

Both must pass for milestone 1 acceptance.

Step 9a — Pin smoke test

Test script: next/tests/smoke_pin.sh

#!/usr/bin/env bash
set -euo pipefail

# 0. Start a fresh fed-sx kernel (background)
./next/scripts/start.sh fresh
sleep 2
TOKEN=$(cat next/data/keys/publish.token)

# 1. Verify actor exists
curl -s http://localhost:9999/actors/next | jq -e '.type == "Person"'

# 2. Verify outbox has actor's first Create{Person}
curl -s http://localhost:9999/actors/next/outbox?page=true \
  | jq -e '.orderedItems | length == 1 and .[0].type == "Create"'

# 3. Verify Pin is NOT a known activity type
curl -s http://localhost:9999/define-registry?kind=activity_types \
  | jq -e '.[] | select(.name == "Pin") | length == 0' || exit 1

# 4. Publish DefineActivity{name: "Pin", schema: ..., semantics: ...}
PIN_DEF=$(cat <<'JSON'
{
  "type": "Create",
  "object": {
    "type": "DefineActivity",
    "name": "Pin",
    "schema": "(fn (act) (and (string? (-> act :object :path)) (cid? (-> act :object :cid))))",
    "semantics": "(fn (state act) (assoc-in state [:pins (-> act :object :path)] (-> act :object :cid)))"
  }
}
JSON
)
curl -s -X POST http://localhost:9999/activity \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/activity+json" \
  -d "$PIN_DEF" | jq -e '.cid' > /dev/null

# 5. Verify Pin IS now a known activity type
curl -s http://localhost:9999/define-registry?kind=activity_types \
  | jq -e '.[] | select(.name == "Pin") | length == 1'

# 6. Also publish a DefineProjection{name: "pin-state"} that folds Pin into state
PIN_PROJ=$(cat <<'JSON'
{
  "type": "Create",
  "object": {
    "type": "DefineProjection",
    "name": "pin-state",
    "initial-state": "{}",
    "fold": "(fn (state act) (if (= (:type act) \"Pin\") (assoc state (-> act :object :path) (-> act :object :cid)) state))"
  }
}
JSON
)
curl -s -X POST http://localhost:9999/activity \
  -H "Authorization: Bearer $TOKEN" \
  -d "$PIN_PROJ" | jq -e '.cid'

# 7. Now publish a Pin activity
PIN=$(cat <<'JSON'
{
  "type": "Pin",
  "object": {
    "type": "PinSpec",
    "path": "/docs/intro",
    "cid": "bafyreigh2akiscaildc3xqxx4xqxx4xqxx4xqxx4xqxx4xqxx4xqxx4xqxxe"
  }
}
JSON
)
curl -s -X POST http://localhost:9999/activity \
  -H "Authorization: Bearer $TOKEN" \
  -d "$PIN" | jq -e '.cid'

# 8. Verify Pin appears in outbox
curl -s http://localhost:9999/actors/next/outbox?page=true \
  | jq -e '.orderedItems | map(select(.type == "Pin")) | length == 1'

# 9. Verify pin-state projection has the entry
sleep 1   # allow async projection
curl -s http://localhost:9999/projections/pin-state \
  | jq -e '."/docs/intro" == "bafyreigh2akiscaildc3xqxx4xqxx4xqxx4xqxx4xqxx4xqxx4xqxx4xqxxe"'

# 10. Negative test: publish a malformed Pin (missing path) → expect 422
BAD_PIN='{"type": "Pin", "object": {"cid": "bafy..."}}'
HTTP_STATUS=$(curl -s -o /dev/null -w "%{http_code}" -X POST http://localhost:9999/activity \
  -H "Authorization: Bearer $TOKEN" -d "$BAD_PIN")
[[ "$HTTP_STATUS" == "422" ]] || { echo "expected 422, got $HTTP_STATUS"; exit 1; }

# 11. Restart kernel; verify state recovers
./next/scripts/stop.sh
./next/scripts/start.sh
sleep 2
curl -s http://localhost:9999/projections/pin-state \
  | jq -e '."/docs/intro" == "bafyreigh2akiscaildc3xqxx4xqxx4xqxx4xqxx4xqxx4xqxx4xqxxe"'

echo "✓ Pin smoke test passed — verb extensibility demonstrated end-to-end"

Acceptance for 9a: smoke test exits 0. The whole flow happens with zero fed-sx kernel code changes between defining the verb and using it.

Step 9b — Reactive application smoke test

The bigger proof point. Demonstrates that fed-sx supports distributed reactive applications composed of DefineSubscription + DefineTrigger + DefineProjection — the application model from §§18-19.

The test runs on a single instance (federation is v2), so the "subscriber" and "publisher" are the same actor. That's intentional — milestone 1 proves the mechanism; milestone 2 spreads it across instances.

Test script: next/tests/smoke_app.sh

#!/usr/bin/env bash
set -euo pipefail

# Assumes 9a has already run (fresh kernel optional; can run alongside).
TOKEN=$(cat next/data/keys/publish.token)
BASE=http://localhost:9999

# 1. Verify "Topic" subscription type and "Subscribe" verb are NOT yet defined.
curl -s "$BASE/define-registry?kind=subscription_types" \
  | jq -e 'map(select(.name == "Topic")) | length == 0'

# 2. Publish DefineSubscription{name: "Topic", ...}
TOPIC_DEF=$(cat <<'JSON'
{
  "type": "Create",
  "object": {
    "type": "DefineSubscription",
    "name": "Topic",
    "schema": "(fn (sub) (string? (-> sub :tag)))",
    "match":  "(fn (sub act) (and (= (:type act) \"Note\") (member? (-> sub :tag) (or (-> act :object :tags) (list)))))",
    "delivery": "{:default :push :modes (list :push :pull)}"
  }
}
JSON
)
curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$TOPIC_DEF" | jq -e '.cid'

# 3. Verify Topic IS now a known subscription type.
curl -s "$BASE/define-registry?kind=subscription_types" \
  | jq -e 'map(select(.name == "Topic")) | length == 1'

# 4. Subscribe to the "smoketest" topic.
SUBSCRIBE=$(cat <<'JSON'
{
  "type": "Subscribe",
  "object": {"type": "Topic", "tag": "smoketest"}
}
JSON
)
SUB_CID=$(curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$SUBSCRIBE" | jq -r '.cid')

# 5. Verify subscriptions projection has the new entry.
sleep 1
curl -s "$BASE/projections/subscriptions" \
  | jq -e '.["https://next.rose-ash.com/actors/next"] | map(select(.type == "Topic")) | length == 1'

# 6. Define a projection that records matched activities (per-application
#    namespace would happen via DefineApplication in v1.x; for v1 the
#    projection is global to the actor).
TOPIC_PROJ=$(cat <<'JSON'
{
  "type": "Create",
  "object": {
    "type": "DefineProjection",
    "name": "topic-events",
    "initial-state": "{}",
    "fold": "(fn (state act) (if (and (= (:type act) \"Note\") (member? \"smoketest\" (or (-> act :object :tags) (list)))) (assoc-in state [(:cid act)] act) state))"
  }
}
JSON
)
curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$TOPIC_PROJ" | jq -e '.cid'

# 7. Define a trigger: when a Topic{smoketest} subscription matches, publish
#    a TestEcho activity. We need an "Echo" activity type first.
ECHO_DEF=$(cat <<'JSON'
{
  "type": "Create",
  "object": {
    "type": "DefineActivity",
    "name": "TestEcho",
    "schema":    "(fn (act) (cid? (-> act :object :echoes)))",
    "semantics": "(fn (state act) state)"
  }
}
JSON
)
curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$ECHO_DEF" | jq -e '.cid'

TRIGGER=$(cat <<JSON
{
  "type": "Create",
  "object": {
    "type": "DefineTrigger",
    "name": "echo-on-smoketest",
    "when-subscription": "$SUB_CID",
    "cascade-limit": 1,
    "then": "(fn (act sub env) {:publish (list {:type \"TestEcho\" :object {:echoes (:cid act)}})})"
  }
}
JSON
)
curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$TRIGGER" | jq -e '.cid'

# 8. Capture outbox length so we can detect new entries.
BEFORE=$(curl -s "$BASE/actors/next/outbox?page=true" \
  | jq -r '.orderedItems | length')

# 9. Publish a Note tagged "smoketest" — should match subscription, fire trigger,
#    cause TestEcho to be published.
NOTE=$(cat <<'JSON'
{
  "type": "Create",
  "object": {
    "type": "Note",
    "content": "hello reactive world",
    "tags": ["smoketest"]
  }
}
JSON
)
NOTE_CID=$(curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$NOTE" | jq -r '.cid')

# 10. Wait for projection + trigger.
sleep 2

# 11. Verify topic-events projection captured the Note.
curl -s "$BASE/projections/topic-events" \
  | jq -e ". | to_entries | length == 1"

# 12. Verify outbox grew by exactly TWO activities (the Note + the trigger's TestEcho).
AFTER=$(curl -s "$BASE/actors/next/outbox?page=true" \
  | jq -r '.orderedItems | length')
[[ $((AFTER - BEFORE)) == 2 ]] || { echo "expected +2 activities, got $((AFTER - BEFORE))"; exit 1; }

# 13. Verify the latest activity is a TestEcho referencing the original Note's CID.
curl -s "$BASE/actors/next/outbox?page=true" \
  | jq -e ".orderedItems[0] | .type == \"TestEcho\" and .object.echoes == \"$NOTE_CID\""

# 14. Negative case: publish a Note WITHOUT the "smoketest" tag — must NOT
#     trigger, must NOT echo.
BEFORE2=$(curl -s "$BASE/actors/next/outbox?page=true" | jq -r '.orderedItems | length')
NOTE_OTHER=$(cat <<'JSON'
{"type": "Create", "object": {"type": "Note", "content": "no match", "tags": ["other"]}}
JSON
)
curl -s -X POST "$BASE/activity" \
  -H "Authorization: Bearer $TOKEN" -d "$NOTE_OTHER" | jq -e '.cid'
sleep 2
AFTER2=$(curl -s "$BASE/actors/next/outbox?page=true" | jq -r '.orderedItems | length')
[[ $((AFTER2 - BEFORE2)) == 1 ]] || { echo "expected +1 activity (no echo), got $((AFTER2 - BEFORE2))"; exit 1; }

# 15. Cascade limit check: prove the trigger doesn't recursively echo TestEcho.
#     The TestEcho activity itself should NOT match the Topic{smoketest}
#     subscription (it's not a Note), so no cascade, but verify cascade-depth
#     was set to 1 on the echo so a future trigger on TestEcho would refuse.
LATEST_ECHO=$(curl -s "$BASE/actors/next/outbox?page=true" \
  | jq -r '.orderedItems | map(select(.type == "TestEcho")) | .[0]')
echo "$LATEST_ECHO" | jq -e '."cascade-depth" == 1'

# 16. Restart kernel; verify subscription, trigger, projection all survive.
./next/scripts/stop.sh
./next/scripts/start.sh
sleep 2
curl -s "$BASE/projections/subscriptions" \
  | jq -e '.["https://next.rose-ash.com/actors/next"] | map(select(.type == "Topic")) | length == 1'
curl -s "$BASE/projections/topic-events" | jq -e ". | to_entries | length >= 1"
curl -s "$BASE/define-registry?kind=triggers" \
  | jq -e 'map(select(.name == "echo-on-smoketest")) | length == 1'

echo "✓ Reactive application smoke test passed — Subscribe + Trigger + Projection demonstrated end-to-end"

What this proves (and what it doesn't):

Proves:

• DefineSubscription + Subscribe mechanism works end-to-end.
• Subscription's match-fn evaluates correctly in pure mode against inbound activities.
• DefineTrigger fires on subscription matches.
• Trigger's then-sx can publish derived activities (the :publish result).
• Cascade-depth metadata propagates correctly.
• Subscription state, trigger registration, and projection state all survive kernel restart (snapshot + log replay).
• The full reactive application loop works without any kernel code changes between defining the components and exercising them.

Does NOT prove (deferred to milestone 2+):

• Cross-instance subscriptions (federation).
• Trigger :effect results calling effectful primitives.
• DefineApplication bundle install/update/fork.
• Per-application namespace isolation.
• Cascade prevention against malicious cascading from peer instances.

Acceptance for 9b: smoke test exits 0. Like 9a, zero fed-sx kernel code changes between defining the application components and observing them operate.

---

Acceptance criteria for milestone 1

All of:

1. Each step's test suite passes (bash next/tests/<step>.sh).
2. Both smoke tests pass (bash next/tests/smoke_pin.sh and bash next/tests/smoke_app.sh).
3. Erlang-on-SX baseline preserved — adding fed-sx kernel modules in next/kernel/*.erl doesn't break Phase 1-8 conformance.
4. Restart durability — kill the kernel mid-write, restart, projections resume from snapshot, no log corruption.
5. Manual Mastodon poke — point a Mastodon account at https://next.rose-ash.com/actors/next and verify the actor doc fetches and webfinger discovery works (read-only AP interop, no follow).

What lands when

This is the work-order an agent (or human) follows. Steps 1-3 can be done in parallel after the Erlang Phase 8 BIFs land. Steps 4-7 are sequential. Step 8 can start in parallel with step 7. Step 9 is the integration test.

Phase 7+8 (loops/erlang) ───┐
                            │
                            ▼
              ┌─── Step 1 ──┬─── Step 2 ──┬─── Step 3
              │             │             │
              └─────────────┼─── Step 4 ──┴────┐
                            │                  │
                            └─── Step 5 ───────┤
                                              │
                                  Step 6 ─────┤
                                              │
                                  Step 7 ─────┤
                                              │
                                  Step 8 ─────┤
                                              │
                                  Step 9 ─────┘

Estimated effort if done by a focused agent loop, one feature per iteration: ~30-50 commits across all 9 steps. Could plausibly be a loops/fed-sx workstream once Phase 7+8 are done.

What's deferred to milestone 2

• Federation (the second-biggest piece). POST /inbox, Follow lifecycle, delivery queue, backfill, capability negotiation between peers. Whole of design §13.
• Multi-actor with per-user OAuth and capability tokens. Design §9.5.
• IPFS storage backend as a DefineStorage entry. Design §15.3.
• Browser client + operator dashboard (probably in Elm-on-SX or similar).
• Rich verbs: Endorse, Supersede, Test, Build, Compose, Note, Announce. All defined as DefineActivity artifacts, federated.
• Cross-host conformance — Python/JS/Haskell hosts running fed-sx. Design §11.8.
• OpenTimestamps proofs as a DefineProof entry.
• Performance work — JIT-compiled folds, snapshot acceleration, federation batching.

Milestone 2 unlocks "real federation between two fed-sx instances." Milestone 3 is the rose-ash port (blog, market, events, federation, account, orders) as fed-sx applications.

---

Appendix A: open questions for milestone 1

A few things still under-specified; resolve as work begins.

1. HTTP server library. Does the Phase 8 http:listen/2 BIF wrap an existing OCaml HTTP server (the sx.rose-ash.com one) or something simpler? Implementation choice deferred to Phase 8.
2. JSON-LD library. AP wire format requires JSON-LD canonicalization for signature coverage. Either pull a library or write a minimal subset for the shapes we actually use. Probably the latter — our envelope is well-defined.
3. Bearer token rotation. v1 uses a single env-var token. Token rotation without restart needs registry-style mgmt; can wait.
4. Snapshot rate limits. Default in design is "every 1000 activities or 60 seconds." Tunable per-projection later; v1 uses the default.
5. Genesis bundle format. Dag-cbor map per §12.2; concrete schema needs one round of refinement once we author the actual definitions in step 4.