Lab #3094: Deliver workflow signals through swamp serve

Problem

swamp-club#3093 delivers a signal by creating a write-once outcome record, but only the CLI can signal, and only on a machine with the repository and its datastore. An outside system cannot call in: there is no server form of workflow signal or workflow waits, and no access action a callback identity could be granted.

This issue is the first of four steps. It covers delivery and authority only. Resume stays manual after it; a signalled run is resumed with the existing workflow resume, locally or through serve.

Proposal

One acceptance use case in libswamp (workflowSignal in src/libswamp/workflows/signal.ts), exposed through the CLI, a WebSocket workflow.signal request and an authenticated HTTP POST.
A server form of the waits listing, and --server forms of swamp workflow signal and swamp workflow waits.
A new signal action beside run, read, write, approve and admin. It allows delivering to a wait on a workflow and nothing else. Proposed: a run grant implies signal, as it implies approve, and a signal-only grant suits a callback identity.
A signal names a wait ID and nothing else, so the workflow to authorize against is known only from the wait's registration. An unknown wait ID and an unauthorized caller get the same answer, so a response does not reveal whether a run exists.
Refusals sent to a caller who cannot read the workflow do not name its workflow, run or step, and do not carry an earlier signal's receipt.
Receipt metadata is written by the server: submittedBy is the authenticated principal, never a value from the request. The submitter is an audit actor and is never the identity that executes downstream steps.
Logs and audit events record receipt IDs and outcomes, never the payload.
The waits listing shows a caller only the waits of workflows they may read or signal.

Open decisions

Does a run grant imply signal? Proposed yes, with a serve flag to require an explicit grant, as runImpliesApprove has.
Whether a signal-only grant may list waits, or only deliver to a wait ID it was given.

Acceptance criteria

A caller holding only a signal grant can deliver a signal over HTTP and over WebSocket, and cannot start, approve, resume or read a run with it.
An unknown wait ID and a wait the caller may not signal are answered identically.
A signal delivered through serve is applied by the next resume exactly as one delivered by the CLI.
All serve instances on a datastore must be upgraded before a workflow with a wait is run; an older instance refuses such a run rather than mishandling it (already the case since swamp-club#3093).

Tests

Access tests for the signal action and for the indistinguishable unknown and unauthorized answers.
Handler tests for payload refusal, an already settled wait and an expired wait over both transports.
CLI and HTTP journeys in swamp-uat.

Follow-ups

swamp-club#3108: resume signalled runs automatically (continuation claim and sweep).
swamp-club#3109: settle expired waits from serve, and a serve-configured maximum timeout.
swamp-club#3110: show signal waits to remote clients and the dashboard.

Out of scope

Everything in the follow-ups, plus provider webhooks that resolve a wait, reserving a wait before a request step, capability links, schema-generated forms, wait_until polling, and leases with fencing for executors.

Depends on

swamp-club#3093 (write-once outcome records), merged.

References

The Wait for Signal section of design/primitives/workflows.md, including Mixing builds and Limits of this version.

Session-start 'swamp model search --json' in the AGENTS.md template is unfulfillable - wire it to a hook or drop it

Flaky property test: analyzeExpression dot/bracket agreement fails when the generated model name is a CEL keyword

Accept usernames for user subjects in grant files

Docs: enable-managed-config should say to re-run config migrate when its push fails

Docs: grant file reference shows a stale format and omits resources and subjects

Flaky property test: analyzeExpression hyphenated dot access fails when modelName generates a CEL keyword ("in")

extension quality and push crash with IsADirectory when additionalFiles lists a directory

extension push: a required global argument renders with a stray "" ("text": "string""")

Docs: extension publishing reference is stale on bare specifiers, quality output and fmt config (swamp-club#3022)

swamp-extensions: replace bare import specifiers with npm:/jsr: specifiers in first-party extensions

extension push: 'Requested visibility' line prints to stdout without the logger prefix, twice per run

A nested structural swamp that outlives the run that started it keeps skipping that run's lock while the holder writes

Show signal waits to remote clients and the dashboard

Settle expired signal waits from swamp serve

Resume signalled workflow runs automatically under swamp serve

extension push/quality: structured acceptances for agents, a clearer title than For next time, and an optional reason

extension push: the undecided private-entitlement verdict still says the registry may start a trial at publish

seed:collective cannot produce a superseded personal trial or a returned trial, so the UAT cannot cover them

Replayable state fragments: Git-reviewable desired state for resources changed by model methods

extension push: registry metadata and content hash label files relative to the repo dir, so a push with --extensions-dir records ../ paths

registry: store and show declared acceptances sent in contentMetadata.acceptances at confirm (swamp-club#3021)

extension push --dry-run: authentication verdict prints 'Signed in as .' when the credential is an API key with no username

serve --remote-only: step output from workers is never persisted to the run log (history logs always empty)

serve HA: worker enrollment on a replica that lacks the enrollment token's definition may create a second definition (unverified)

serve HA: pull a token's definition on an auth miss so a peer accepts a new token at once

extension push: version-drift check reports 'no previously published version found' when the registry call failed

Search and list output follows directory iteration order in the definition, workflow, vault and output repositories

extension push: accept attestation-backed adversarial-review evidence (lookup by extension and content hash), generated provenance, and carry the evidence to the registry at confirm (design: Lab #3023)

Workflow load errors print the raw Zod issue dump instead of a readable message

Decide a stricter naming rule for workflow step and job names

serve: run scheduled workflows concurrently (per-workflow serialization), and report queue delay

Show expired approval gates as expired, with a Cancel action in the dashboard

digitalocean codegen leaves an orphaned security_secret.ts model file after its endpoint left the spec

extension promote accepts a yanked version and reports it promoted

Docs: doctor install reports a stale or failing autoupdate scheduler

extension push output: double-quoted adjacent interpolations, repo-relative paths, and --json emits three JSON documents

auto-resolve: the Installing line prints the extension's entire multi-line description

s3-datastore/serve: readResource without a version returns an older version; the latest marker is rewritten backwards

Publish agent-facing projections of the manual: /llms.txt, .md pages, and llms-full.txt

Let agent-runner drive more agent CLIs (Kilo Code and others)

s3-datastore: every fast-path miss re-downloads every _index shard, so a busy serve pulls the whole index every poll (~230 GB/day S3 egress)

Feedback: Swamp as an approval-gated control plane for a small fleet

extension safety analyzer's Deno.Command( warning is a plain substring match

Tell timeouts apart from cancels in method-run records, and review the hidden 30 s fallback timer for step-called model methods

Run from a git worktree: definitions from the worktree, state from the shared repo

S3/GCS datastore: a push that fails after uploading drops its recorded deletes, so the retry brings deleted data back

Tests: bring the in-memory remote's default semantics up to @swamp/s3-datastore and @swamp/gcs-datastore 2026.10.01.1

Tell the pushing client when its extension contentMetadata fails validation

Extension datastore: query still returns an item after its delete is pulled

Cancel, reject and supersede of a parent run should settle its suspended nested child runs

Relationships

#3094 Deliver workflow signals through swamp serve