Merge branch 'fix/coordinator-worker-integration'

STATUS.md

@@ -1,7 +1,7 @@
 # SciMesh Status
 
 **Updated:** 2026-07-23  
-**Branch baseline:** `planning` at `13f9a0b`
+**Branch baseline:** `main` at `b4a89dd` (coordinator merge)
 
 ## Current state
 
@@ -15,39 +15,43 @@ the reference behaviour for future distributed execution:
 - Python Worker skeleton: claim, heartbeat, input checksum validation,
   artifact upload, completion and failure reporting.
 
-The Go coordinator, PostgreSQL schema, coordinator artifact storage, planner,
+The Go coordinator and its PostgreSQL-backed task lifecycle are implemented:
-reducer, and end-to-end distributed execution are **not implemented yet**.
+registration, atomic claiming, lease renewal, artifact storage, dataset
+chunking, result/failure reporting, and job progress. The Python worker now
+uses the live coordinator contract; its HTTP path was exercised against a real
+Docker PostgreSQL stack on 2026-07-23.
 
 ## Milestone tracker
 
 | CTX | Status | Notes |
 | --- | --- | --- |
-| CTX-00 API and error contract | Ready to implement | `docs/api-contract.md` created; needs owner review/freeze. |
+| CTX-00 API and error contract | Implemented | Contract, OpenAPI, and request examples are in `docs/`. |
-| CTX-01 Go coordinator bootstrap | Not started | Depends on CTX-00. |
+| CTX-01 Go coordinator bootstrap | Implemented | Go service and Docker runtime in `coordinator/`. |
-| CTX-02 PostgreSQL migrations | Not started | Depends on CTX-00 and CTX-01. |
+| CTX-02 PostgreSQL migrations | Implemented | Applied by the Compose migration service. |
-| CTX-03 Transactional queue | Not started | Depends on CTX-02. |
+| CTX-03 Transactional queue | Implemented | Real-PostgreSQL integration tests cover atomic claims and concurrency. |
-| CTX-04 Worker registry and HTTP API | Not started | Depends on CTX-03. |
+| CTX-04 Worker registry and HTTP API | Implemented | Registration, claim, heartbeat, result, failure, and status endpoints. |
-| CTX-05 Artifact storage | Not started | Depends on CTX-02 and CTX-04. |
+| CTX-05 Artifact storage | Implemented | Coordinator-owned inputs/results, checksum verification, and upload flow. |
-| CTX-06 Python Worker live-contract alignment | Partially prepared | Worker skeleton exists; needs real Go contract tests. |
+| CTX-06 Python Worker live-contract alignment | Implemented | Worker completed a real uploaded shard via HTTP on 2026-07-23. |
 | CTX-07 Distributed workload protocol | Not started | Depends on artifact and Worker contracts. |
 | CTX-08 Distributed similarity-search | Not started | Local reference exists. |
 | CTX-09 Reducer and final-result API | Not started | Depends on CTX-07 and CTX-08. |
 | CTX-10 Distributed similarity-graph | Not started | Local reference exists. |
 | CTX-11 Dashboard/operator view | Not started | Deferred until API and reducer work. |
-| CTX-12 Reliability, security, CI | Not started | Final milestone. |
+| CTX-12 Reliability, security, CI | In progress | Unit, race, PostgreSQL integration, and smoke checks exist; CI hardening remains. |
 
 ## Next recommended assignment
 
-Assign **CTX-00** to the coordinator role in `.agents/coordinator.md`: review
+Assign **CTX-07** to the workload role: define distributed job planning and
-and freeze `docs/api-contract.md` against `PLAN.md`. Do not begin coordinator
+reduction boundaries before implementing distributed search or graph execution.
-or Worker API implementation until the contract owner accepts it.
 
 ## Known constraints
 
-- Distributed execution is not available; use the local `scimesh` CLI.
+- Planner/reducer semantics are not implemented; use the local `scimesh` CLI
-- No Go module, PostgreSQL migrations, runtime configuration, or integration
+  for complete workload results.
-  environment exists yet.
+- The worker/coordinator flow currently accepts both underscore API workload
-- Local worker unit tests do not prove interoperability with a live coordinator.
+  names and hyphenated CLI names while the contract is consolidated.
+- A real-stack worker test uses a small `query_smiles` shard. Resolving a
+  `query_id` once and sharing it across shards belongs to CTX-07.
 
 ## Update rule
 

coordinator/Makefile

@@ -1,5 +1,15 @@
 .PHONY: build run test test-integration vet lint tidy check migrate-up migrate-down up down down-clean logs ps rebuild psql smoke
 
+# `check` deliberately uses its own Compose project and host ports. This keeps
+# it from connecting to or replacing a developer's local PostgreSQL instance.
+CHECK_PROJECT ?= scimesh-check
+CHECK_POSTGRES_PORT ?= 55432
+CHECK_COORDINATOR_PORT ?= 18080
+CHECK_HOST ?= http://localhost:$(CHECK_COORDINATOR_PORT)
+CHECK_TOKEN ?= dev-token
+CHECK_DATABASE_URL ?= postgres://scimesh:scimesh@localhost:$(CHECK_POSTGRES_PORT)/scimesh?sslmode=disable
+CHECK_COMPOSE = POSTGRES_PORT=$(CHECK_POSTGRES_PORT) COORDINATOR_PORT=$(CHECK_COORDINATOR_PORT) docker compose -p $(CHECK_PROJECT)
+
 # --- build / run ---------------------------------------------------------
 build:
 	go build ./...
@@ -23,12 +33,16 @@ vet:
 # Needs Docker. Hand this to a reviewer.
 check: vet lint
 	go test -race ./...
-	docker compose up -d --build
+	$(CHECK_COMPOSE) up -d --build
 	@echo "waiting for the coordinator to be ready..."
-	@sleep 6
+	@attempt=0; until curl -fsS "$(CHECK_HOST)/health" >/dev/null; do \
-	TEST_DATABASE_URL='postgres://scimesh:scimesh@localhost:5432/scimesh?sslmode=disable' \
+		attempt=$$((attempt + 1)); \
+		if [ $$attempt -ge 30 ]; then $(CHECK_COMPOSE) logs coordinator; exit 1; fi; \
+		sleep 1; \
+	done
+	TEST_DATABASE_URL="$(CHECK_DATABASE_URL)" \
 		go test -tags=integration ./internal/storage/postgres/ -v
-	./scripts/smoke.sh
+	HOST="$(CHECK_HOST)" TOKEN="$(CHECK_TOKEN)" ./scripts/smoke.sh
 	@echo "\nall checks passed ✓"
 
 # Runs golangci-lint without installing it system-wide. Install it for speed:

coordinator/README.md

@@ -169,3 +169,14 @@ make test-integration TEST_DATABASE_URL='postgres://scimesh:scimesh@localhost:54
 
 CI (`.github/workflows/coordinator.yml`) runs vet, gofmt, race tests, lint, and
 the integration suite against a Postgres service on every push and PR.
+
+For the complete local verification, including an isolated Docker PostgreSQL
+and the HTTP smoke flow, run:
+
+```sh
+make check
+```
+
+It uses Compose project `scimesh-check` and ports `55432`/`18080` by default,
+so it does not connect to a PostgreSQL already running on `5432`. Override
+`CHECK_POSTGRES_PORT`, `CHECK_COORDINATOR_PORT`, or `CHECK_PROJECT` if needed.

coordinator/internal/domain/artifact.go

@@ -23,6 +23,7 @@ type Artifact struct {
 	ID          uuid.UUID
 	JobID       uuid.UUID
 	TaskID      *uuid.UUID // nil for a job-level input
+	Attempt     *int       // required for a partial result; nil for non-worker artifacts
 	Kind        ArtifactKind
 	Filename    string
 	StorageKey  string

coordinator/internal/domain/task.go

@@ -117,8 +117,10 @@ const DefaultMaxAttempts = 3
 func (t *Task) CanRetry() bool { return t.Attempt < t.MaxAttempts }
 
 // IsLeaseHeldBy reports whether worker currently holds this task at attempt.
-func (t *Task) IsLeaseHeldBy(worker string, attempt int) bool {
+func (t *Task) IsLeaseHeldBy(worker string, attempt int, now time.Time) bool {
-	return t.LeaseOwner != nil && *t.LeaseOwner == worker && t.Attempt == attempt
+	return t.LeaseOwner != nil && t.LeaseExpiresAt != nil && now.Before(*t.LeaseExpiresAt) &&
+		*t.LeaseOwner == worker && t.Attempt == attempt &&
+		(t.Status == TaskLeased || t.Status == TaskRunning)
 }
 
 // AsClaimed projects the task into the trimmed view handed to a worker:
@@ -146,7 +148,7 @@ func (t *Task) AsClaimed() ClaimedTask {
 
 // verifyLease is the guard every worker-driven transition shares: the caller
 // must own the lease and reference the attempt it was granted.
-func (t *Task) verifyLease(worker string, attempt int) error {
+func (t *Task) verifyLease(worker string, attempt int, now time.Time) error {
 	// A task is worker-owned while leased or running: the first heartbeat moves
 	// it from leased to running, but ownership rules are identical for both.
 	if t.Status != TaskLeased && t.Status != TaskRunning {
@@ -158,13 +160,16 @@ func (t *Task) verifyLease(worker string, attempt int) error {
 	if t.Attempt != attempt {
 		return ErrStaleAttempt
 	}
+	if t.LeaseExpiresAt == nil || !now.Before(*t.LeaseExpiresAt) {
+		return ErrLeaseConflict
+	}
 	return nil
 }
 
 // RenewLease extends the lease of the worker that holds it. The first heartbeat
 // also acknowledges start, moving the task from leased to running.
-func (t *Task) RenewLease(worker string, attempt int, until time.Time) error {
+func (t *Task) RenewLease(worker string, attempt int, now, until time.Time) error {
-	if err := t.verifyLease(worker, attempt); err != nil {
+	if err := t.verifyLease(worker, attempt, now); err != nil {
 		return err
 	}
 	t.LeaseExpiresAt = &until
@@ -195,7 +200,7 @@ func (t *Task) CompleteWith(resultArtifactID uuid.UUID, metrics map[string]any,
 		return ErrResultConflict
 	}
 
-	if err := t.verifyLease(worker, attempt); err != nil {
+	if err := t.verifyLease(worker, attempt, now); err != nil {
 		return err
 	}
 
@@ -214,7 +219,7 @@ func (t *Task) CompleteWith(resultArtifactID uuid.UUID, metrics map[string]any,
 // Fail records a worker-reported failure. A retryable failure with attempts
 // left returns the task to the queue; otherwise it terminates as failed.
 func (t *Task) Fail(worker string, attempt int, code, message string, retryable bool, now time.Time) error {
-	if err := t.verifyLease(worker, attempt); err != nil {
+	if err := t.verifyLease(worker, attempt, now); err != nil {
 		return err
 	}
 	t.ErrorCode = &code

coordinator/internal/domain/task_test.go

@@ -172,14 +172,14 @@ func TestFirstHeartbeatMovesLeasedToRunning(t *testing.T) {
 	task := leasedTask(1, 3)
 	until := testLater.Add(time.Hour)
 
-	if err := task.RenewLease(testWorker, 1, until); err != nil {
+	if err := task.RenewLease(testWorker, 1, testNow, until); err != nil {
 		t.Fatal(err)
 	}
 	if task.Status != TaskRunning {
 		t.Errorf("status = %q, want running after first heartbeat", task.Status)
 	}
 	// A second heartbeat keeps it running.
-	if err := task.RenewLease(testWorker, 1, until); err != nil {
+	if err := task.RenewLease(testWorker, 1, testNow, until); err != nil {
 		t.Fatal(err)
 	}
 	if task.Status != TaskRunning {
@@ -190,15 +190,15 @@ func TestFirstHeartbeatMovesLeasedToRunning(t *testing.T) {
 func TestRunningTaskCanBeCompletedAndExpired(t *testing.T) {
 	// Complete works from running.
 	task := leasedTask(1, 3)
-	_ = task.RenewLease(testWorker, 1, testLater) // -> running
+	_ = task.RenewLease(testWorker, 1, testNow, testLater) // -> running
 	if err := task.CompleteWith(testResult, nil, testWorker, 1, testNow); err != nil {
 		t.Errorf("complete from running: %v", err)
 	}
 
 	// Expire reclaims a running task too.
 	task2 := leasedTask(1, 3)
-	_ = task2.RenewLease(testWorker, 1, testLater) // -> running
+	_ = task2.RenewLease(testWorker, 1, testNow, testLater) // -> running
-	task2.ExpireLease(testNow)
+	task2.ExpireLease(testLater)
 	if task2.Status != TaskPending {
 		t.Errorf("status = %q, want pending after a running lease expires", task2.Status)
 	}
@@ -208,14 +208,29 @@ func TestRenewLeaseExtendsOnlyForHolder(t *testing.T) {
 	task := leasedTask(1, 3)
 	until := testLater.Add(time.Hour)
 
-	if err := task.RenewLease(testWorker, 1, until); err != nil {
+	if err := task.RenewLease(testWorker, 1, testNow, until); err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
 	if !task.LeaseExpiresAt.Equal(until) {
 		t.Error("lease must be extended")
 	}
 
-	if err := task.RenewLease("worker-2", 1, until); !errors.Is(err, ErrLeaseConflict) {
+	if err := task.RenewLease("worker-2", 1, testNow, until); !errors.Is(err, ErrLeaseConflict) {
 		t.Errorf("err = %v, want ErrLeaseConflict", err)
 	}
 }
+
+func TestExpiredLeaseRejectsRenewalCompletionAndFailure(t *testing.T) {
+	task := leasedTask(1, 3)
+	expired := testLater.Add(time.Nanosecond)
+
+	if err := task.RenewLease(testWorker, 1, expired, expired.Add(time.Minute)); !errors.Is(err, ErrLeaseConflict) {
+		t.Errorf("renew expired lease: err = %v, want ErrLeaseConflict", err)
+	}
+	if err := task.CompleteWith(testResult, nil, testWorker, 1, expired); !errors.Is(err, ErrLeaseConflict) {
+		t.Errorf("complete expired lease: err = %v, want ErrLeaseConflict", err)
+	}
+	if err := task.Fail(testWorker, 1, "timeout", "expired", true, expired); !errors.Is(err, ErrLeaseConflict) {
+		t.Errorf("fail expired lease: err = %v, want ErrLeaseConflict", err)
+	}
+}

coordinator/internal/storage/postgres/artifact_repo.go

@@ -26,14 +26,14 @@ func NewArtifactRepo(pool *pgxpool.Pool) *ArtifactRepo {
 var _ usecase.ArtifactRepository = (*ArtifactRepo)(nil)
 
 var artifactColumns = []string{
-	"id", "job_id", "task_id", "kind", "filename", "storage_key",
+	"id", "job_id", "task_id", "attempt", "kind", "filename", "storage_key",
 	"content_type", "size_bytes", "sha256", "created_at",
 }
 
 func (r *ArtifactRepo) Insert(ctx context.Context, a *domain.Artifact) error {
 	sql, args, err := psql.Insert("artifacts").
 		Columns(artifactColumns...).
-		Values(a.ID, a.JobID, a.TaskID, string(a.Kind), a.Filename, a.StorageKey,
+		Values(a.ID, a.JobID, a.TaskID, a.Attempt, string(a.Kind), a.Filename, a.StorageKey,
 			a.ContentType, a.SizeBytes, a.SHA256, a.CreatedAt).
 		ToSql()
 	if err != nil {
@@ -59,7 +59,7 @@ func (r *ArtifactRepo) Get(ctx context.Context, id uuid.UUID) (*domain.Artifact,
 		kind string
 	)
 	err = conn(ctx, r.pool).QueryRow(ctx, sql, args...).Scan(
-		&a.ID, &a.JobID, &a.TaskID, &kind, &a.Filename, &a.StorageKey,
+		&a.ID, &a.JobID, &a.TaskID, &a.Attempt, &kind, &a.Filename, &a.StorageKey,
 		&a.ContentType, &a.SizeBytes, &a.SHA256, &a.CreatedAt)
 	if errors.Is(err, pgx.ErrNoRows) {
 		return nil, domain.ErrArtifactNotFound

coordinator/internal/storage/postgres/integration_test.go

@@ -223,7 +223,7 @@ func TestUpdateRejectsStaleVersion(t *testing.T) {
 		if err != nil {
 			return err
 		}
-		if err := fresh.RenewLease("worker-1", fresh.Attempt, now.Add(2*time.Minute)); err != nil {
+		if err := fresh.RenewLease("worker-1", fresh.Attempt, now, now.Add(2*time.Minute)); err != nil {
 			return err
 		}
 		return repo.Update(ctx, fresh)
@@ -259,6 +259,8 @@ func TestListCompletedIsOrderedByChunkIndex(t *testing.T) {
 				return err
 			}
 			art.SetContent(fmt.Sprintf("rsha-%d", task.ChunkIndex), 1)
+			attempt := 1
+			art.Attempt = &attempt
 			if err := artifacts.Insert(ctx, art); err != nil {
 				return err
 			}
@@ -269,6 +271,7 @@ func TestListCompletedIsOrderedByChunkIndex(t *testing.T) {
 			}
 			owner := "worker-1"
 			fresh.Status = domain.TaskLeased
+			fresh.Attempt = attempt
 			fresh.LeaseOwner = &owner
 			expires := now.Add(time.Minute)
 			fresh.LeaseExpiresAt = &expires
@@ -350,6 +353,10 @@ func seedArtifact(t *testing.T, pool *pgxpool.Pool, jobID uuid.UUID, taskID *uui
 		t.Fatalf("build artifact: %v", err)
 	}
 	art.SetContent(fmt.Sprintf("sha-%s", art.ID), 3)
+	if kind == domain.ArtifactPartialResult {
+		attempt := 1
+		art.Attempt = &attempt
+	}
 	if err := NewArtifactRepo(pool).Insert(context.Background(), art); err != nil {
 		t.Fatalf("insert artifact: %v", err)
 	}
@@ -446,6 +453,32 @@ func TestArtifactRepoRoundTrip(t *testing.T) {
 	}
 }
 
+func TestPartialResultArtifactRoundTripsAttempt(t *testing.T) {
+	pool := testPool(t)
+	ctx := context.Background()
+	job, tasks := seedJob(t, pool, 1)
+	taskID := tasks[0].ID
+	art, err := domain.NewArtifact(job.ID, &taskID, domain.ArtifactPartialResult,
+		"result.csv", "text/csv", time.Now().UTC())
+	if err != nil {
+		t.Fatal(err)
+	}
+	attempt := 2
+	art.Attempt = &attempt
+	art.SetContent("sha", 3)
+	repo := NewArtifactRepo(pool)
+	if err := repo.Insert(ctx, art); err != nil {
+		t.Fatalf("insert: %v", err)
+	}
+	got, err := repo.Get(ctx, art.ID)
+	if err != nil {
+		t.Fatalf("get: %v", err)
+	}
+	if got.Attempt == nil || *got.Attempt != attempt {
+		t.Fatalf("attempt = %v, want %d", got.Attempt, attempt)
+	}
+}
+
 // A shard task stores its input as an artifact and no URI: this exercises the
 // nullable input_uri column, the input_artifact_id round-trip, and the
 // ck_tasks_has_input check that requires one or the other.

coordinator/internal/transport/http/errors.go

@@ -3,6 +3,7 @@ package http
 import (
 	"encoding/json"
 	"errors"
+	"io"
 	"net/http"
 
 	"github.com/emil28092005/SciMesh/coordinator/internal/domain"
@@ -24,7 +25,13 @@ func decodeJSON(r *http.Request, dst any) error {
 	// Reject unknown fields: silently ignoring a misspelled "worker_ID" would
 	// surface later as a baffling validation failure.
 	dec.DisallowUnknownFields()
-	return dec.Decode(dst)
+	if err := dec.Decode(dst); err != nil {
+		return err
+	}
+	if err := dec.Decode(&struct{}{}); !errors.Is(err, io.EOF) {
+		return errors.New("request body must contain exactly one JSON value")
+	}
+	return nil
 }
 
 // writeError translates domain errors into status codes. This mapping is the

coordinator/internal/transport/http/handlers.go

@@ -194,11 +194,14 @@ func (s *Server) handleUploadDataset(w http.ResponseWriter, r *http.Request) {
 	}
 
 	var (
-		workload   string
+		workload    string
-		params     map[string]any
+		params      map[string]any
-		rows       = defaultChunkRows
+		rows        = defaultChunkRows
-		result     usecase.SubmitDatasetResult
+		result      usecase.SubmitDatasetResult
-		gotDataset bool
+		gotDataset  bool
+		gotWorkload bool
+		gotParams   bool
+		gotRows     bool
 	)
 
 	for {
@@ -213,9 +216,18 @@ func (s *Server) handleUploadDataset(w http.ResponseWriter, r *http.Request) {
 
 		switch part.FormName() {
 		case "workload":
+			if gotDataset || gotWorkload {
+				s.writeError(w, r, domain.ErrInvalidInput)
+				return
+			}
 			b, _ := io.ReadAll(io.LimitReader(part, 1<<10))
 			workload = strings.TrimSpace(string(b))
+			gotWorkload = true
 		case "parameters":
+			if gotDataset || gotParams {
+				s.writeError(w, r, domain.ErrInvalidInput)
+				return
+			}
 			b, _ := io.ReadAll(io.LimitReader(part, 1<<16))
 			if len(b) > 0 {
 				if err := json.Unmarshal(b, &params); err != nil {
@@ -223,12 +235,25 @@ func (s *Server) handleUploadDataset(w http.ResponseWriter, r *http.Request) {
 					return
 				}
 			}
+			gotParams = true
 		case "chunk_rows":
-			b, _ := io.ReadAll(io.LimitReader(part, 32))
+			if gotDataset || gotRows {
-			if n, err := strconv.Atoi(strings.TrimSpace(string(b))); err == nil {
+				s.writeError(w, r, domain.ErrInvalidInput)
-				rows = n
+				return
 			}
+			b, _ := io.ReadAll(io.LimitReader(part, 32))
+			n, err := strconv.Atoi(strings.TrimSpace(string(b)))
+			if err != nil || n < 1 {
+				s.writeError(w, r, domain.ErrInvalidInput)
+				return
+			}
+			rows = n
+			gotRows = true
 		case "file", "dataset":
+			if gotDataset || workload == "" {
+				s.writeError(w, r, domain.ErrInvalidInput)
+				return
+			}
 			filename := part.FileName()
 			if filename == "" {
 				filename = "dataset"
@@ -246,6 +271,9 @@ func (s *Server) handleUploadDataset(w http.ResponseWriter, r *http.Request) {
 				return
 			}
 			gotDataset = true
+		default:
+			s.writeError(w, r, domain.ErrInvalidInput)
+			return
 		}
 		_ = part.Close()
 	}

coordinator/internal/transport/http/server_test.go

@@ -259,6 +259,37 @@ func TestErrorMappings(t *testing.T) {
 	}
 }
 
+func TestJSONRejectsTrailingValue(t *testing.T) {
+	e := newEnv(t, healthy)
+	if code, _ := e.do(t, "POST", "/workers/register",
+		`{"name":"lab","capabilities":["w"]} {}`); code != http.StatusBadRequest {
+		t.Errorf("status = %d, want 400", code)
+	}
+}
+
+func TestUploadDatasetRejectsAmbiguousMultipartInput(t *testing.T) {
+	e := newEnv(t, healthy)
+	var buf bytes.Buffer
+	mw := multipart.NewWriter(&buf)
+	_ = mw.WriteField("workload", "w")
+	_ = mw.WriteField("chunk_rows", "not-a-number")
+	fw, _ := mw.CreateFormFile("file", "chembl.tsv")
+	_, _ = io.Copy(fw, strings.NewReader("id\tsmiles\nA\tCC\n"))
+	_ = mw.Close()
+
+	req, _ := http.NewRequestWithContext(context.Background(), "POST", e.ts.URL+"/jobs/upload", &buf)
+	req.Header.Set("Authorization", "Bearer "+token)
+	req.Header.Set("Content-Type", mw.FormDataContentType())
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusBadRequest {
+		t.Errorf("status = %d, want 400", resp.StatusCode)
+	}
+}
+
 // --- helpers -------------------------------------------------------------
 
 func (e *env) putArtifact(t *testing.T, taskID, worker string, attempt int, data string) string {

coordinator/internal/usecase/artifact.go

@@ -29,7 +29,7 @@ func (uc *UploadArtifact) Execute(ctx context.Context, in UploadArtifactInput) (
 	}
 	// Only the worker holding the current lease at this attempt may upload the
 	// task's output — the coordinator never trusts an ownership claim on faith.
-	if !task.IsLeaseHeldBy(in.WorkerID, in.Attempt) {
+	if !task.IsLeaseHeldBy(in.WorkerID, in.Attempt, uc.clk.Now()) {
 		return nil, domain.ErrLeaseConflict
 	}
 
@@ -39,6 +39,8 @@ func (uc *UploadArtifact) Execute(ctx context.Context, in UploadArtifactInput) (
 	if err != nil {
 		return nil, err
 	}
+	attempt := in.Attempt
+	art.Attempt = &attempt
 
 	// Stream to storage first: size and checksum are measured here, by us, not
 	// taken from the worker. A large shard never sits in memory.
@@ -48,6 +50,19 @@ func (uc *UploadArtifact) Execute(ctx context.Context, in UploadArtifactInput) (
 	}
 	art.SetContent(sum, size)
 
+	// The stream may take longer than the lease. Re-check after it finishes so
+	// an expired worker cannot leave a durable result record behind. Completion
+	// performs the same ownership check under its transaction.
+	current, err := uc.tasks.Get(ctx, in.TaskID)
+	if err != nil {
+		_ = uc.blobs.Delete(ctx, art.StorageKey)
+		return nil, err
+	}
+	if !current.IsLeaseHeldBy(in.WorkerID, in.Attempt, uc.clk.Now()) {
+		_ = uc.blobs.Delete(ctx, art.StorageKey)
+		return nil, domain.ErrLeaseConflict
+	}
+
 	// Persist the record. If that fails the blob would be an orphan, so remove it.
 	if err := uc.artifacts.Insert(ctx, art); err != nil {
 		_ = uc.blobs.Delete(ctx, art.StorageKey)

coordinator/internal/usecase/task.go

@@ -91,7 +91,8 @@ func (uc *RenewLease) Execute(ctx context.Context, in RenewLeaseInput) (*domain.
 		if err != nil {
 			return err
 		}
-		if err := task.RenewLease(in.WorkerID, in.Attempt, uc.clock.Now().Add(uc.leaseDuration)); err != nil {
+		now := uc.clock.Now()
+		if err := task.RenewLease(in.WorkerID, in.Attempt, now, now.Add(uc.leaseDuration)); err != nil {
 			return err
 		}
 		if err := uc.tasks.Update(ctx, task); err != nil {
@@ -143,7 +144,7 @@ func (uc *CompleteTask) Execute(ctx context.Context, in CompleteTaskInput) (*dom
 		}
 		// Rule 10: never trust a worker-supplied artifact reference. The result
 		// must be an artifact the coordinator itself stored for *this* task.
-		if err := uc.verifyResultArtifact(ctx, in.TaskID, in.ResultArtifactID); err != nil {
+		if err := uc.verifyResultArtifact(ctx, in.TaskID, in.Attempt, in.ResultArtifactID); err != nil {
 			return err
 		}
 		now := uc.clock.Now()
@@ -175,12 +176,12 @@ func (uc *CompleteTask) Execute(ctx context.Context, in CompleteTaskInput) (*dom
 // verifyResultArtifact enforces that the referenced artifact was stored by the
 // coordinator for this exact task. It stops a worker from completing task B with
 // an artifact it uploaded for task A, and from naming an id that isn't a result.
-func (uc *CompleteTask) verifyResultArtifact(ctx context.Context, taskID, artifactID uuid.UUID) error {
+func (uc *CompleteTask) verifyResultArtifact(ctx context.Context, taskID uuid.UUID, attempt int, artifactID uuid.UUID) error {
 	art, err := uc.artifacts.Get(ctx, artifactID)
 	if err != nil {
 		return err
 	}
-	if art.TaskID == nil || *art.TaskID != taskID || art.Kind != domain.ArtifactPartialResult {
+	if art.TaskID == nil || *art.TaskID != taskID || art.Attempt == nil || *art.Attempt != attempt || art.Kind != domain.ArtifactPartialResult {
 		return domain.ErrResultConflict
 	}
 	return nil

coordinator/internal/usecase/usecase_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"strings"
 	"testing"
 	"time"
@@ -19,6 +20,17 @@ var ctx = context.Background()
 
 const lease = 2 * time.Minute
 
+type expiringBlobStore struct {
+	*memstore.BlobStore
+	clock *memstore.Clock
+}
+
+func (s expiringBlobStore) Put(ctx context.Context, key string, body io.Reader) (string, int64, error) {
+	sum, size, err := s.BlobStore.Put(ctx, key, body)
+	s.clock.Advance(lease + time.Second)
+	return sum, size, err
+}
+
 // harness wires every use case to in-memory stores so orchestration can be
 // tested without a database.
 type harness struct {
@@ -239,6 +251,46 @@ func TestCompleteRejectsForeignArtifact(t *testing.T) {
 	}
 }
 
+func TestCompleteRejectsArtifactFromExpiredAttempt(t *testing.T) {
+	h := newHarness()
+	h.seedJob(t, "w", 1)
+	taskID, attemptOne := h.leaseOne(t, "w1", "w")
+	staleArtifact := h.uploadResult(t, taskID, "w1", attemptOne)
+
+	h.clk.Advance(lease + time.Second)
+	if _, err := h.expire.Execute(ctx); err != nil {
+		t.Fatalf("expire lease: %v", err)
+	}
+	_, attemptTwo := h.leaseOne(t, "w2", "w")
+	if attemptTwo != attemptOne+1 {
+		t.Fatalf("attempt = %d, want %d", attemptTwo, attemptOne+1)
+	}
+
+	_, err := h.complete.Execute(ctx, usecase.CompleteTaskInput{
+		TaskID: taskID, WorkerID: "w2", Attempt: attemptTwo, ResultArtifactID: staleArtifact,
+	})
+	if !errors.Is(err, domain.ErrResultConflict) {
+		t.Errorf("stale-attempt artifact: err = %v, want ErrResultConflict", err)
+	}
+}
+
+func TestUploadRejectsLeaseThatExpiresDuringStreaming(t *testing.T) {
+	h := newHarness()
+	h.seedJob(t, "w", 1)
+	taskID, attempt := h.leaseOne(t, "w1", "w")
+	h.uploadArt = usecase.NewUploadArtifact(
+		h.tasks, h.arts, expiringBlobStore{BlobStore: h.blobs, clock: h.clk}, h.clk,
+	)
+
+	_, err := h.uploadArt.Execute(ctx, usecase.UploadArtifactInput{
+		TaskID: taskID, WorkerID: "w1", Attempt: attempt,
+		Filename: "result.csv", ContentType: "text/csv", Body: strings.NewReader("result"),
+	})
+	if !errors.Is(err, domain.ErrLeaseConflict) {
+		t.Errorf("upload after lease expiry: err = %v, want ErrLeaseConflict", err)
+	}
+}
+
 func TestCompleteIsIdempotentOnReplay(t *testing.T) {
 	h := newHarness()
 	h.seedJob(t, "w", 1)

coordinator/migrations/0008_artifact_attempt.down.sql

@@ -0,0 +1,7 @@
+BEGIN;
+
+ALTER TABLE artifacts DROP CONSTRAINT IF EXISTS ck_artifact_attempt_positive;
+ALTER TABLE artifacts DROP CONSTRAINT IF EXISTS ck_partial_result_attempt;
+ALTER TABLE artifacts DROP COLUMN IF EXISTS attempt;
+
+COMMIT;

coordinator/migrations/0008_artifact_attempt.up.sql

@@ -0,0 +1,34 @@
+BEGIN;
+
+-- A partial result belongs to the lease attempt that uploaded it. Without this
+-- binding a worker holding a later retry could complete a task with stale bytes
+-- uploaded by an expired attempt of that same task.
+ALTER TABLE artifacts ADD COLUMN attempt integer;
+
+-- A completed task never gets a later lease, so its current attempt is also
+-- the attempt that produced the stored result.
+UPDATE artifacts AS a
+SET attempt = t.attempt
+FROM tasks AS t
+WHERE a.task_id = t.id
+  AND a.kind = 'partial_result'::artifact_kind
+  AND t.status = 'completed'::task_status
+  AND a.attempt IS NULL;
+
+-- For unfinished tasks the old schema cannot tell which attempt uploaded a
+-- partial result. Keeping it would let a later retry claim stale bytes, so the
+-- worker must upload again. Blob garbage is harmless and follows the existing
+-- coordinator-owned storage cleanup policy.
+DELETE FROM artifacts AS a
+USING tasks AS t
+WHERE a.task_id = t.id
+  AND a.kind = 'partial_result'::artifact_kind
+  AND t.status <> 'completed'::task_status
+  AND a.attempt IS NULL;
+
+ALTER TABLE artifacts ADD CONSTRAINT ck_partial_result_attempt
+    CHECK (kind <> 'partial_result'::artifact_kind OR attempt IS NOT NULL);
+ALTER TABLE artifacts ADD CONSTRAINT ck_artifact_attempt_positive
+    CHECK (attempt IS NULL OR attempt > 0);
+
+COMMIT;

docs/building-workers.md

@@ -56,6 +56,8 @@ Response: `{ "worker_id": "<uuid>", "heartbeat_interval_seconds": 15 }`.
 - **Keep `worker_id`**. Use it as your identity in every later call. Using the
   registered UUID is what lets the coordinator track your liveness (it marks
   workers offline after they go silent).
+- Current coordinator jobs use `similarity_search` / `similarity_graph`; the
+  reference Python worker also accepts the public CLI spellings with hyphens.
 
 ## 2. Claim a task
 
@@ -185,7 +187,8 @@ next claim.
 Per the worker contract, at minimum:
 
 - `SCIMESH_COORDINATOR_URL` (e.g. `http://coordinator:8080`)
-- `SCIMESH_WORKER_ID` (or derive from hostname)
+- worker name (the coordinator returns its `worker_id` at registration;
+  `SCIMESH_WORKER_ID` is only a legacy/test override)
 - the bearer token
 - poll interval and request timeout
 - a working directory for downloaded inputs and generated outputs

scimesh/worker/artifacts.py

@@ -7,38 +7,23 @@ import http.client
 import json
 from pathlib import Path
 from typing import Protocol
-from urllib.parse import quote, urlsplit
+from urllib.parse import quote, urljoin, urlsplit
-from urllib.request import HTTPRedirectHandler, Request, build_opener
+from urllib.request import Request, build_opener
 
-from .models import ClaimedTask, ProducedArtifact
+from .coordinator import CoordinatorConflictError
+from .models import ClaimedTask, ProducedArtifact, UploadedArtifact
+from .transport import SameOriginAuthRedirectHandler, origin
 
-
+# Compatibility aliases for focused transport tests.
-def _origin(uri: str) -> tuple[str, str, int | None]:
+_SameOriginAuthRedirectHandler = SameOriginAuthRedirectHandler
-    parsed = urlsplit(uri)
+_origin = origin
-    scheme = parsed.scheme.lower()
-    default_port = {"http": 80, "https": 443}.get(scheme)
-    return scheme, (parsed.hostname or "").lower(), parsed.port or default_port
-
-
-class _SameOriginAuthRedirectHandler(HTTPRedirectHandler):
-    """Do not forward the coordinator token when a download changes origin."""
-
-    def __init__(self, coordinator_origin: tuple[str, str, int | None]) -> None:
-        super().__init__()
-        self.coordinator_origin = coordinator_origin
-
-    def redirect_request(self, req: Request, fp: object, code: int, msg: str, headers: object, newurl: str) -> Request | None:
-        redirected = super().redirect_request(req, fp, code, msg, headers, newurl)
-        if redirected and _origin(newurl) != self.coordinator_origin:
-            redirected.remove_header("Authorization")
-        return redirected
 
 class ArtifactClient(Protocol):
     def download(self, uri: str, destination: Path) -> None: ...
 
     def upload(
         self, task: ClaimedTask, worker_id: str, artifact: ProducedArtifact
-    ) -> str: ...
+    ) -> UploadedArtifact: ...
 
 
 class HttpArtifactClient:
@@ -48,18 +33,21 @@ class HttpArtifactClient:
         self.coordinator_url = coordinator_url.rstrip("/")
         self.timeout = timeout
         self.bearer_token = bearer_token
-        self.coordinator_origin = _origin(coordinator_url)
+        self.coordinator_origin = origin(coordinator_url)
-        self._opener = build_opener(_SameOriginAuthRedirectHandler(self.coordinator_origin))
+        self._opener = build_opener(SameOriginAuthRedirectHandler(self.coordinator_origin))
 
     def download(self, uri: str, destination: Path) -> None:
         destination.parent.mkdir(parents=True, exist_ok=True)
-        request = Request(uri, headers=self._auth_headers_for(uri))
+        resolved_uri = urljoin(f"{self.coordinator_url}/", uri)
+        request = Request(resolved_uri, headers=self._auth_headers_for(resolved_uri))
         with self._opener.open(request, timeout=self.timeout) as response, destination.open("wb") as target:
             while chunk := response.read(1024 * 1024):
                 target.write(chunk)
 
-    def upload(self, task: ClaimedTask, worker_id: str, artifact: ProducedArtifact) -> str:
+    def upload(
-        """Stream one result artifact to the coordinator and return its stable URI."""
+        self, task: ClaimedTask, worker_id: str, artifact: ProducedArtifact
+    ) -> UploadedArtifact:
+        """Stream an artifact and require durable coordinator-owned metadata."""
         url = (
             f"{self.coordinator_url}/tasks/{quote(task.task_id, safe='')}/artifacts/"
             f"{quote(artifact.path.name, safe='')}"
@@ -71,11 +59,13 @@ class HttpArtifactClient:
             http.client.HTTPSConnection if parsed.scheme == "https" else http.client.HTTPConnection
         )
         connection = connection_class(parsed.hostname, parsed.port, timeout=self.timeout)
+        local_size = artifact.path.stat().st_size
+        local_sha256 = sha256_file(artifact.path)
         try:
             path = parsed.path + (f"?{parsed.query}" if parsed.query else "")
             connection.putrequest("PUT", path)
             connection.putheader("Content-Type", artifact.content_type)
-            connection.putheader("Content-Length", str(artifact.path.stat().st_size))
+            connection.putheader("Content-Length", str(local_size))
             connection.putheader("X-Worker-ID", worker_id)
             connection.putheader("X-Task-Attempt", str(task.attempt))
             for name, value in self._auth_headers_for(url).items():
@@ -86,23 +76,24 @@ class HttpArtifactClient:
                     connection.send(chunk)
             response = connection.getresponse()
             body = response.read()
-            if not 200 <= response.status < 300:
+            if response.status == 409:
+                raise CoordinatorConflictError("artifact upload rejected because the task lease was lost")
+            if response.status != 200:
                 raise RuntimeError(f"artifact upload rejected with status {response.status}")
-            if body:
+            try:
-                try:
+                response_data = json.loads(body)
-                    response_data = json.loads(body)
+                uploaded = UploadedArtifact.from_json(response_data)
-                except json.JSONDecodeError as error:
+            except (ValueError, json.JSONDecodeError) as error:
-                    raise RuntimeError("artifact upload returned invalid JSON") from error
+                raise RuntimeError("artifact upload returned invalid metadata") from error
-                response_uri = response_data.get("uri") if isinstance(response_data, dict) else None
+            if uploaded.sha256 != local_sha256 or uploaded.size_bytes != local_size:
-                if isinstance(response_uri, str) and response_uri:
+                raise RuntimeError("artifact upload metadata does not match local artifact")
-                    return response_uri
+            return uploaded
-            return url
         finally:
             connection.close()
 
     def _auth_headers_for(self, uri: str) -> dict[str, str]:
         """Only coordinator-owned URLs receive the coordinator bearer token."""
-        if self.bearer_token and _origin(uri) == self.coordinator_origin:
+        if self.bearer_token and origin(uri) == self.coordinator_origin:
             return {"Authorization": f"Bearer {self.bearer_token}"}
         return {}
 

scimesh/worker/cli.py

@@ -14,22 +14,42 @@ from .runners import SciMeshRunner
 
 
 def main(argv: list[str] | None = None) -> int:
-    parser = argparse.ArgumentParser(prog="scimesh-worker")
+    parser = argparse.ArgumentParser(
+        prog="scimesh-worker",
+        epilog=(
+            "Environment: SCIMESH_COORDINATOR_URL, SCIMESH_WORK_DIR, "
+            "SCIMESH_WORKER_NAME, SCIMESH_CPU_COUNT, SCIMESH_MEMORY_MB, "
+            "SCIMESH_POLL_INTERVAL, SCIMESH_REQUEST_TIMEOUT, "
+            "SCIMESH_HEARTBEAT_INTERVAL, SCIMESH_CLEANUP_AFTER_SECONDS, and "
+            "SCIMESH_BEARER_TOKEN. SCIMESH_WORKER_ID is a legacy/test override."
+        ),
+    )
     parser.add_argument("--coordinator-url")
     parser.add_argument("--worker-id")
     parser.add_argument("--work-dir")
+    parser.add_argument("--worker-name")
+    parser.add_argument("--cpu-count", type=int)
+    parser.add_argument("--memory-mb", type=int)
     parser.add_argument("--poll-interval", type=float)
     parser.add_argument("--request-timeout", type=float)
     parser.add_argument("--heartbeat-interval", type=float)
+    parser.add_argument("--cleanup-after-seconds", type=float)
     args = parser.parse_args(argv)
-    config = WorkerConfig.from_environment()
     overrides = {key: value for key, value in vars(args).items() if value is not None}
     if "work_dir" in overrides:
         overrides["work_dir"] = Path(overrides["work_dir"])
-    config = WorkerConfig(**{**config.__dict__, **overrides})
+    try:
+        config = WorkerConfig.from_environment(overrides)
+    except (TypeError, ValueError) as error:
+        parser.error(str(error))
     logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")
     client = HttpCoordinatorClient(config.coordinator_url, config.request_timeout, config.bearer_token)
-    WorkerDaemon(config, client, HttpArtifactClient(config.coordinator_url, config.request_timeout, config.bearer_token), SciMeshRunner()).run_forever()
+    WorkerDaemon(
+        config,
+        client,
+        HttpArtifactClient(config.coordinator_url, config.request_timeout, config.bearer_token),
+        SciMeshRunner(),
+    ).run_forever()
     return 0
 
 

scimesh/worker/config.py

@@ -3,44 +3,99 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from math import isfinite
 from pathlib import Path
 import os
+import socket
+from typing import Mapping
+from urllib.parse import urlsplit
+
+
+def _positive_number(value: object, name: str, *, allow_zero: bool = False) -> None:
+    if (
+        isinstance(value, bool)
+        or not isinstance(value, (int, float))
+        or not isfinite(value)
+        or value < 0
+        or (not allow_zero and value == 0)
+    ):
+        qualifier = "non-negative" if allow_zero else "positive"
+        raise ValueError(f"{name} must be {qualifier}")
 
 
 @dataclass(frozen=True)
 class WorkerConfig:
     coordinator_url: str
-    worker_id: str
+    worker_id: str | None
     work_dir: Path
+    worker_name: str = "scimesh-worker"
+    cpu_count: int = 1
+    memory_mb: int | None = None
     poll_interval: float = 2.0
     request_timeout: float = 30.0
     heartbeat_interval: float = 15.0
     bearer_token: str | None = None
     cleanup_after_seconds: float | None = None
-    capabilities: tuple[str, ...] = ("similarity-search", "similarity-graph")
+    # The local CLI uses hyphens; the first coordinator contract used
+    # underscores. Advertise both stable spellings while jobs are migrated.
+    capabilities: tuple[str, ...] = (
+        "similarity-search",
+        "similarity-graph",
+        "similarity_search",
+        "similarity_graph",
+    )
 
     def __post_init__(self) -> None:
-        if self.poll_interval <= 0:
+        parsed = urlsplit(self.coordinator_url)
-            raise ValueError("poll_interval must be positive")
+        if parsed.scheme not in {"http", "https"} or not parsed.hostname:
-        if self.request_timeout <= 0:
+            raise ValueError("coordinator_url must be an absolute HTTP(S) URL")
-            raise ValueError("request_timeout must be positive")
+        if not isinstance(self.worker_name, str) or not self.worker_name.strip():
-        if self.heartbeat_interval <= 0:
+            raise ValueError("worker_name must be non-empty")
-            raise ValueError("heartbeat_interval must be positive")
+        if isinstance(self.cpu_count, bool) or not isinstance(self.cpu_count, int) or self.cpu_count < 1:
+            raise ValueError("cpu_count must be positive")
+        if self.worker_id is not None and not isinstance(self.worker_id, str):
+            raise ValueError("worker_id must be a string when set")
+        if self.memory_mb is not None and (
+            isinstance(self.memory_mb, bool)
+            or not isinstance(self.memory_mb, int)
+            or self.memory_mb < 1
+        ):
+            raise ValueError("memory_mb must be positive when set")
+        _positive_number(self.poll_interval, "poll_interval")
+        _positive_number(self.request_timeout, "request_timeout")
+        _positive_number(self.heartbeat_interval, "heartbeat_interval")
+        if self.cleanup_after_seconds is not None:
+            _positive_number(self.cleanup_after_seconds, "cleanup_after_seconds", allow_zero=True)
+        if not self.capabilities:
+            raise ValueError("capabilities cannot be empty")
 
     @classmethod
-    def from_environment(cls) -> "WorkerConfig":
+    def from_environment(
-        url = os.getenv("SCIMESH_COORDINATOR_URL")
+        cls, overrides: Mapping[str, object] | None = None
-        worker_id = os.getenv("SCIMESH_WORKER_ID")
+    ) -> "WorkerConfig":
-        if not url or not worker_id:
+        """Build config from environment, allowing typed CLI values to override it."""
-            raise ValueError("SCIMESH_COORDINATOR_URL and SCIMESH_WORKER_ID are required")
+        values = overrides or {}
-        cleanup = os.getenv("SCIMESH_CLEANUP_AFTER_SECONDS")
+
+        def value(name: str, environment: str, default: object | None = None) -> object | None:
+            override = values.get(name)
+            return override if override is not None else os.getenv(environment, default)
+
+        url = value("coordinator_url", "SCIMESH_COORDINATOR_URL")
+        if not isinstance(url, str) or not url:
+            raise ValueError("SCIMESH_COORDINATOR_URL or --coordinator-url is required")
+        cleanup = value("cleanup_after_seconds", "SCIMESH_CLEANUP_AFTER_SECONDS")
+        cpu_count = value("cpu_count", "SCIMESH_CPU_COUNT", os.cpu_count() or 1)
+        memory_mb = value("memory_mb", "SCIMESH_MEMORY_MB")
         return cls(
             coordinator_url=url.rstrip("/"),
-            worker_id=worker_id,
+            worker_id=value("worker_id", "SCIMESH_WORKER_ID"),
-            work_dir=Path(os.getenv("SCIMESH_WORK_DIR", "./scimesh-worker-data")),
+            work_dir=Path(value("work_dir", "SCIMESH_WORK_DIR", "./scimesh-worker-data")),
-            poll_interval=float(os.getenv("SCIMESH_POLL_INTERVAL", "2")),
+            worker_name=str(value("worker_name", "SCIMESH_WORKER_NAME", socket.gethostname())),
-            request_timeout=float(os.getenv("SCIMESH_REQUEST_TIMEOUT", "30")),
+            cpu_count=int(cpu_count),
-            heartbeat_interval=float(os.getenv("SCIMESH_HEARTBEAT_INTERVAL", "15")),
+            memory_mb=int(memory_mb) if memory_mb is not None else None,
-            bearer_token=os.getenv("SCIMESH_BEARER_TOKEN"),
+            poll_interval=float(value("poll_interval", "SCIMESH_POLL_INTERVAL", "2")),
+            request_timeout=float(value("request_timeout", "SCIMESH_REQUEST_TIMEOUT", "30")),
+            heartbeat_interval=float(value("heartbeat_interval", "SCIMESH_HEARTBEAT_INTERVAL", "15")),
+            bearer_token=value("bearer_token", "SCIMESH_BEARER_TOKEN"),
             cleanup_after_seconds=float(cleanup) if cleanup else None,
         )

scimesh/worker/coordinator.py

@@ -5,9 +5,10 @@ from __future__ import annotations
 import json
 from typing import Any, Protocol
 from urllib.error import HTTPError, URLError
-from urllib.request import Request, urlopen
+from urllib.request import Request, build_opener
 
-from .models import ClaimedTask
+from .models import ClaimedTask, RegisteredWorker
+from .transport import NoRedirectHandler
 
 
 class CoordinatorError(RuntimeError):
@@ -18,7 +19,15 @@ class CoordinatorTransientError(CoordinatorError):
     """A timeout, connection error, or 5xx coordinator response."""
 
 
+class CoordinatorConflictError(CoordinatorError):
+    """The worker no longer owns the task lease or attempted a conflicting mutation."""
+
+
 class CoordinatorClient(Protocol):
+    def register(
+        self, name: str, capabilities: tuple[str, ...], cpu_count: int, memory_mb: int | None
+    ) -> RegisteredWorker: ...
+
     def claim(self, worker_id: str, capabilities: tuple[str, ...]) -> ClaimedTask | None: ...
 
     def submit(self, task: ClaimedTask, payload: dict[str, Any]) -> None: ...
@@ -33,6 +42,25 @@ class HttpCoordinatorClient:
         self.base_url = base_url.rstrip("/")
         self.timeout = timeout
         self.bearer_token = bearer_token
+        self._opener = build_opener(NoRedirectHandler())
+
+    def register(
+        self, name: str, capabilities: tuple[str, ...], cpu_count: int, memory_mb: int | None
+    ) -> RegisteredWorker:
+        payload: dict[str, Any] = {
+            "name": name,
+            "capabilities": list(capabilities),
+            "cpu_count": cpu_count,
+        }
+        if memory_mb is not None:
+            payload["memory_mb"] = memory_mb
+        status, body = self._request("POST", "/workers/register", payload)
+        if status != 201:
+            raise CoordinatorError(f"worker registration rejected with status {status}")
+        try:
+            return RegisteredWorker.from_json(body)
+        except ValueError as error:
+            raise CoordinatorError("invalid worker registration response") from error
 
     def claim(self, worker_id: str, capabilities: tuple[str, ...]) -> ClaimedTask | None:
         status, body = self._request("POST", "/tasks/claim", {
@@ -48,11 +76,15 @@ class HttpCoordinatorClient:
         status, _ = self._request("POST", f"/tasks/{task.task_id}/result", payload)
         # 200/201/202 include a successful or idempotent duplicate result response.
         if status not in (200, 201, 202):
+            if status == 409:
+                raise CoordinatorConflictError("result rejected because the task lease was lost")
             raise CoordinatorError(f"result rejected with status {status}")
 
     def fail(self, task: ClaimedTask, payload: dict[str, Any]) -> None:
         status, _ = self._request("POST", f"/tasks/{task.task_id}/failure", payload)
         if status not in (200, 201, 202):
+            if status == 409:
+                raise CoordinatorConflictError("failure rejected because the task lease was lost")
             raise CoordinatorError(f"failure report rejected with status {status}")
 
     def heartbeat(self, task: ClaimedTask, worker_id: str) -> str:
@@ -61,6 +93,8 @@ class HttpCoordinatorClient:
             {"worker_id": worker_id, "attempt": task.attempt},
         )
         if status != 200:
+            if status == 409:
+                raise CoordinatorConflictError("heartbeat rejected because the task lease was lost")
             raise CoordinatorError(f"heartbeat rejected with status {status}")
         lease_expires_at = body.get("lease_expires_at")
         if not isinstance(lease_expires_at, str):
@@ -73,9 +107,12 @@ class HttpCoordinatorClient:
             headers={"Content-Type": "application/json", **self._auth_header()},
         )
         try:
-            with urlopen(request, timeout=self.timeout) as response:
+            with self._opener.open(request, timeout=self.timeout) as response:
                 raw = response.read()
-                return response.status, json.loads(raw) if raw else {}
+                try:
+                    return response.status, json.loads(raw) if raw else {}
+                except json.JSONDecodeError as error:
+                    raise CoordinatorError("coordinator returned invalid JSON") from error
         except HTTPError as error:
             if error.code >= 500:
                 raise CoordinatorTransientError(f"coordinator returned {error.code}") from error

scimesh/worker/daemon.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import logging
+from dataclasses import replace
 from pathlib import Path
 import random
 import shutil
@@ -12,8 +13,8 @@ from datetime import datetime, timezone
 
 from .artifacts import ArtifactClient, sha256_file
 from .config import WorkerConfig
-from .coordinator import CoordinatorClient, CoordinatorTransientError
+from .coordinator import CoordinatorClient, CoordinatorConflictError, CoordinatorTransientError
-from .models import ClaimedTask
+from .models import ClaimedTask, UploadedArtifact
 from .runners import Runner
 
 
@@ -32,6 +33,7 @@ class LeaseHeartbeat:
         self._lease_expires_at = self.coordinator.heartbeat(
             self.task, self.config.worker_id
         )
+        self._next_delay()
         self._thread = threading.Thread(target=self._run, name=f"lease-{self.task.task_id}", daemon=True)
         self._thread.start()
 
@@ -45,18 +47,19 @@ class LeaseHeartbeat:
             raise self._error
 
     def _run(self) -> None:
-        delay = min(self.config.heartbeat_interval, self._seconds_until_expiry() / 2)
+        delay = self._next_delay()
         while not self._stop.wait(max(delay, 0.01)):
             try:
                 self._lease_expires_at = self.coordinator.heartbeat(
                     self.task, self.config.worker_id
                 )
+                delay = self._next_delay()
             except Exception as error:  # Surface the lease loss in the main state machine.
                 self._error = error
                 return
-            delay = min(
+
-                self.config.heartbeat_interval, self._seconds_until_expiry() / 2
+    def _next_delay(self) -> float:
-            )
+        return min(self.config.heartbeat_interval, self._seconds_until_expiry() / 2)
 
     def _seconds_until_expiry(self) -> float:
         try:
@@ -72,12 +75,16 @@ class LeaseHeartbeat:
 class WorkerDaemon:
     def __init__(self, config: WorkerConfig, coordinator: CoordinatorClient, artifacts: ArtifactClient, runner: Runner) -> None:
         self.config, self.coordinator, self.artifacts, self.runner = config, coordinator, artifacts, runner
+        self.worker_id = config.worker_id
+        self._registered = False
         self.log = logging.getLogger("scimesh.worker")
 
     def run_forever(self) -> None:
         failures = 0
         while True:
             try:
+                if not self._registered:
+                    self._register_worker()
                 self._cleanup_expired_directories()
                 claimed = self.run_once()
                 failures = 0
@@ -89,16 +96,17 @@ class WorkerDaemon:
                 self._sleep(min(self.config.poll_interval * 2 ** min(failures, 6), 60.0))
 
     def run_once(self) -> bool:
+        worker_id = self._worker_id()
         self._log("claiming")
-        task = self.coordinator.claim(self.config.worker_id, self.config.capabilities)
+        task = self.coordinator.claim(worker_id, self.config.capabilities)
         if task is None:
             self._log("idle")
             return False
         started = time.monotonic()
         task_dir = self.config.work_dir / task.task_id / str(task.attempt)
-        task_dir.mkdir(parents=True, exist_ok=False)
         heartbeat = LeaseHeartbeat(task, self.coordinator, self.config)
         try:
+            task_dir.mkdir(parents=True, exist_ok=False)
             heartbeat.start()
             self._log("downloading", task)
             input_path = task_dir / "input"
@@ -108,20 +116,28 @@ class WorkerDaemon:
             self._log("running", task)
             result = self.runner.run(task, task_dir)
             heartbeat.raise_if_failed()
-            manifests = [
+            if len(result.artifacts) != 1:
-                {
+                raise ValueError("runner must produce exactly one result artifact")
-                    "uri": self.artifacts.upload(task, self.config.worker_id, artifact),
+            artifact = result.artifacts[0]
-                    "sha256": sha256_file(artifact.path),
+            uploaded = self.artifacts.upload(task, worker_id, artifact)
-                    "content_type": artifact.content_type,
+            manifest = self._result_manifest(uploaded)
-                }
-                for artifact in result.artifacts
-            ]
-            if not manifests:
-                raise ValueError("runner produced no artifacts")
             self._log("submitting", task)
             heartbeat.raise_if_failed()
-            self.coordinator.submit(task, {"worker_id": self.config.worker_id, "attempt": task.attempt, "status": "completed", "result": manifests[0], "artifacts": manifests, "metrics": {**result.metrics, "elapsed_seconds": round(time.monotonic() - started, 3)}})
+            self.coordinator.submit(
+                task,
+                {
+                    "worker_id": worker_id,
+                    "attempt": task.attempt,
+                    "result": manifest,
+                    "metrics": {
+                        **result.metrics,
+                        "elapsed_seconds": round(time.monotonic() - started, 3),
+                    },
+                },
+            )
             self._log("idle", task, elapsed_seconds=round(time.monotonic() - started, 3))
+        except CoordinatorConflictError as error:
+            self._log("lease_lost", task, error_type=type(error).__name__)
         except Exception as error:
             self._log("failed", task, error_type=type(error).__name__)
             self._report_failure(task, error)
@@ -132,12 +148,38 @@ class WorkerDaemon:
     def _report_failure(self, task: ClaimedTask, error: Exception) -> None:
         message = str(error).replace(str(self.config.work_dir), "<worker-dir>")[:300]
         try:
-            self.coordinator.fail(task, {"worker_id": self.config.worker_id, "attempt": task.attempt, "error_code": type(error).__name__, "error_message": message})
+            self.coordinator.fail(task, {"worker_id": self._worker_id(), "attempt": task.attempt, "error_code": type(error).__name__, "error_message": message})
         except CoordinatorTransientError:
             raise
         except Exception:
             self._log("failed", task, error_type="FailureReportError")
 
+    def _register_worker(self) -> None:
+        registered = self.coordinator.register(
+            self.config.worker_name,
+            self.config.capabilities,
+            self.config.cpu_count,
+            self.config.memory_mb,
+        )
+        self.worker_id = registered.worker_id
+        self.config = replace(
+            self.config,
+            worker_id=registered.worker_id,
+            heartbeat_interval=registered.heartbeat_interval_seconds,
+        )
+        self._registered = True
+        self._log("registered")
+
+    def _worker_id(self) -> str:
+        if not self.worker_id:
+            raise ValueError("worker is not registered")
+        return self.worker_id
+
+    @staticmethod
+    def _result_manifest(uploaded: UploadedArtifact) -> dict[str, object]:
+        """Keep completion payload exact: coordinator owns all artifact metadata."""
+        return {"artifact_id": uploaded.artifact_id}
+
     def _log(self, state: str, task: ClaimedTask | None = None, **extra: object) -> None:
         fields = {"worker_id": self.config.worker_id, "task_id": task.task_id if task else None, "attempt": task.attempt if task else None, "state": state, **extra}
         self.log.info("worker_event %s", fields)

scimesh/worker/models.py

@@ -3,8 +3,40 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from datetime import datetime
+from math import isfinite
 from pathlib import Path
 from typing import Any
+from urllib.parse import urlsplit
+from uuid import UUID
+
+
+def _required_string(value: object, field: str) -> str:
+    if not isinstance(value, str) or not value.strip():
+        raise ValueError(f"{field} must be a non-empty string")
+    return value
+
+
+def _coordinator_uri(value: object, field: str) -> str:
+    uri = _required_string(value, field)
+    parsed = urlsplit(uri)
+    if uri.startswith("/"):
+        # ``//host/path`` is a network-path reference: urljoin would resolve
+        # it to another origin. Dot segments are rejected for the same reason
+        # we reject unsafe local task identifiers.
+        if parsed.netloc or any(segment == ".." for segment in parsed.path.split("/")):
+            raise ValueError(f"{field} must be a safe coordinator path")
+        return uri
+    if parsed.scheme not in {"http", "https"} or not parsed.hostname:
+        raise ValueError(f"{field} must be an absolute HTTP(S) URL or coordinator path")
+    return uri
+
+
+def _sha256(value: object, field: str) -> str:
+    digest = _required_string(value, field).lower()
+    if len(digest) != 64 or any(character not in "0123456789abcdef" for character in digest):
+        raise ValueError(f"{field} must be a SHA-256 hex digest")
+    return digest
 
 
 @dataclass(frozen=True)
@@ -26,13 +58,28 @@ class ClaimedTask:
     def from_json(cls, data: dict[str, Any]) -> "ClaimedTask":
         try:
             input_data = data["input"]
+            if not isinstance(input_data, dict):
+                raise ValueError("input must be an object")
+            raw_attempt = data["attempt"]
+            if isinstance(raw_attempt, bool) or not isinstance(raw_attempt, int) or raw_attempt < 1:
+                raise ValueError("attempt must be a positive integer")
+            task_id = str(UUID(_required_string(data["task_id"], "task_id")))
+            lease_expires_at = _required_string(data["lease_expires_at"], "lease_expires_at")
+            if datetime.fromisoformat(lease_expires_at.replace("Z", "+00:00")).tzinfo is None:
+                raise ValueError("lease_expires_at must include a timezone")
+            parameters = data.get("parameters", {})
+            if not isinstance(parameters, dict):
+                raise ValueError("parameters must be an object")
             return cls(
-                task_id=str(data["task_id"]),
+                task_id=task_id,
-                attempt=int(data["attempt"]),
+                attempt=raw_attempt,
-                lease_expires_at=str(data["lease_expires_at"]),
+                lease_expires_at=lease_expires_at,
-                workload=str(data["workload"]),
+                workload=_required_string(data["workload"], "workload"),
-                input=InputArtifact(uri=str(input_data["uri"]), sha256=str(input_data["sha256"])),
+                input=InputArtifact(
-                parameters=dict(data.get("parameters", {})),
+                    uri=_coordinator_uri(input_data["uri"], "input.uri"),
+                    sha256=_sha256(input_data["sha256"], "input.sha256"),
+                ),
+                parameters=parameters,
             )
         except (KeyError, TypeError, ValueError) as error:
             raise ValueError("invalid claimed-task response") from error
@@ -44,6 +91,61 @@ class ProducedArtifact:
     content_type: str
 
 
+@dataclass(frozen=True)
+class UploadedArtifact:
+    """Coordinator-owned artifact metadata returned after a successful upload."""
+
+    artifact_id: str
+    uri: str
+    sha256: str
+    size_bytes: int
+
+    @classmethod
+    def from_json(cls, data: object) -> "UploadedArtifact":
+        if not isinstance(data, dict):
+            raise ValueError("artifact upload response must be an object")
+        raw_size = data.get("size_bytes")
+        if isinstance(raw_size, bool) or not isinstance(raw_size, int) or raw_size < 0:
+            raise ValueError("artifact size_bytes must be a non-negative integer")
+        try:
+            return cls(
+                artifact_id=str(UUID(_required_string(data.get("artifact_id"), "artifact_id"))),
+                uri=_coordinator_uri(data.get("uri"), "uri"),
+                sha256=_sha256(data.get("sha256"), "sha256"),
+                size_bytes=raw_size,
+            )
+        except ValueError as error:
+            raise ValueError("invalid artifact upload response") from error
+
+
+@dataclass(frozen=True)
+class RegisteredWorker:
+    """Identity and heartbeat policy returned by worker registration."""
+
+    worker_id: str
+    heartbeat_interval_seconds: float
+
+    @classmethod
+    def from_json(cls, data: object) -> "RegisteredWorker":
+        if not isinstance(data, dict):
+            raise ValueError("worker registration response must be an object")
+        raw_interval = data.get("heartbeat_interval_seconds")
+        if (
+            isinstance(raw_interval, bool)
+            or not isinstance(raw_interval, (int, float))
+            or not isfinite(raw_interval)
+            or raw_interval <= 0
+        ):
+            raise ValueError("heartbeat_interval_seconds must be positive")
+        try:
+            return cls(
+                worker_id=str(UUID(_required_string(data.get("worker_id"), "worker_id"))),
+                heartbeat_interval_seconds=float(raw_interval),
+            )
+        except ValueError as error:
+            raise ValueError("invalid worker registration response") from error
+
+
 @dataclass(frozen=True)
 class RunResult:
     artifacts: tuple[ProducedArtifact, ...]

scimesh/worker/runners.py

@@ -20,9 +20,13 @@ class SciMeshRunner:
     def run(self, task: ClaimedTask, task_dir: Path) -> RunResult:
         input_path = task_dir / "input"
         output_path = task_dir / "result.csv"
-        command = [sys.executable, "-m", "scimesh.cli", task.workload, str(input_path)]
+        # The coordinator contract historically used underscores while the
+        # public SciMesh CLI uses hyphens. Accept both spellings at this narrow
+        # boundary so an API job cannot turn into an opaque worker failure.
+        workload = task.workload.replace("_", "-")
+        command = [sys.executable, "-m", "scimesh.cli", workload, str(input_path)]
         params = task.parameters
-        if task.workload == "similarity-search":
+        if workload == "similarity-search":
             self._reject_unknown(params, {"query_id", "query_smiles", "top_k", "threshold", "threshold_direction", "max_rows", "progress_every"})
             query_id, query_smiles = params.get("query_id"), params.get("query_smiles")
             if (query_id is None) == (query_smiles is None):
@@ -31,7 +35,7 @@ class SciMeshRunner:
             command += ["--query-id", self._string(params, "query_id")] if query_id is not None else ["--query-smiles", self._string(params, "query_smiles")]
             command += ["--top-k", str(top_k)]
             self._append_common_options(command, params)
-        elif task.workload == "similarity-graph":
+        elif workload == "similarity-graph":
             self._reject_unknown(params, {"threshold", "threshold_direction", "block_size", "max_rows", "progress_every"})
             threshold = self._number(params, "threshold")
             command += ["--threshold", str(threshold)]

scimesh/worker/transport.py

@@ -0,0 +1,51 @@
+"""Small HTTP transport helpers shared by coordinator and artifact clients."""
+
+from __future__ import annotations
+
+from urllib.request import HTTPRedirectHandler, Request
+from urllib.parse import urlsplit
+
+
+def origin(uri: str) -> tuple[str, str, int | None]:
+    """Return a normalized HTTP origin for authorization decisions."""
+    parsed = urlsplit(uri)
+    scheme = parsed.scheme.lower()
+    default_port = {"http": 80, "https": 443}.get(scheme)
+    return scheme, (parsed.hostname or "").lower(), parsed.port or default_port
+
+
+class SameOriginAuthRedirectHandler(HTTPRedirectHandler):
+    """Strip coordinator authorization when an artifact redirect changes origin."""
+
+    def __init__(self, coordinator_origin: tuple[str, str, int | None]) -> None:
+        super().__init__()
+        self.coordinator_origin = coordinator_origin
+
+    def redirect_request(
+        self,
+        req: Request,
+        fp: object,
+        code: int,
+        msg: str,
+        headers: object,
+        newurl: str,
+    ) -> Request | None:
+        redirected = super().redirect_request(req, fp, code, msg, headers, newurl)
+        if redirected and origin(newurl) != self.coordinator_origin:
+            redirected.remove_header("Authorization")
+        return redirected
+
+
+class NoRedirectHandler(HTTPRedirectHandler):
+    """Reject redirects for mutating coordinator API calls."""
+
+    def redirect_request(
+        self,
+        req: Request,
+        fp: object,
+        code: int,
+        msg: str,
+        headers: object,
+        newurl: str,
+    ) -> Request | None:
+        return None

scimesh/workloads/similarity_graph.py

@@ -47,10 +47,15 @@ def _fingerprinted_molecules(
     tsv_path: Path, max_rows: int | None
 ) -> tuple[list[GraphMolecule], DatasetStats]:
     stats = DatasetStats()
-    molecules = [
+    molecules: list[GraphMolecule] = []
-        GraphMolecule(record.molecule_id, fingerprint(record.molecule))
+    seen_ids: set[str] = set()
-        for record in iter_valid_molecules(tsv_path, stats, max_rows=max_rows)
+    for record in iter_valid_molecules(tsv_path, stats, max_rows=max_rows):
-    ]
+        if not record.molecule_id:
+            raise ValueError("Dataset contains an empty chembl_id")
+        if record.molecule_id in seen_ids:
+            raise ValueError(f"Dataset contains a duplicate chembl_id: {record.molecule_id}")
+        seen_ids.add(record.molecule_id)
+        molecules.append(GraphMolecule(record.molecule_id, fingerprint(record.molecule)))
     return molecules, stats
 
 
@@ -119,6 +124,7 @@ def build_similarity_graph(
 
 def write_graph_edges(output_path: Path, edges: list[SimilarityEdge]) -> None:
     """Write a deterministic sparse edge list CSV."""
+    output_path.parent.mkdir(parents=True, exist_ok=True)
     with output_path.open("w", encoding="utf-8", newline="") as destination:
         writer = csv.DictWriter(destination, fieldnames=["source_id", "target_id", "similarity"])
         writer.writeheader()

scimesh/workloads/similarity_search.py

@@ -135,6 +135,7 @@ def search_similar(
 
 def write_search_results(output_path: Path, matches: list[SimilarityMatch]) -> None:
     """Write ranked matches to a deterministic CSV file."""
+    output_path.parent.mkdir(parents=True, exist_ok=True)
     with output_path.open("w", encoding="utf-8", newline="") as destination:
         writer = csv.DictWriter(
             destination,

tests/test_similarity_graph.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 from pathlib import Path
 
+import pytest
 from rdkit import DataStructs
 
 from scimesh.chemistry.dataset import DatasetStats, iter_valid_molecules
@@ -61,3 +62,19 @@ def test_graph_supports_less_than_threshold_direction(small_dataset: Path) -> No
     )
 
     assert all(edge.similarity <= 0.15 for edge in result.edges)
+
+
+def test_graph_rejects_duplicate_identifiers(tmp_path: Path) -> None:
+    dataset = tmp_path / "duplicate_ids.tsv"
+    dataset.write_text(
+        "chembl_id\tcanonical_smiles\nDUP\tCCO\nDUP\tCCC\n", encoding="utf-8"
+    )
+
+    with pytest.raises(ValueError, match="duplicate chembl_id"):
+        build_similarity_graph(dataset, threshold=0.1, block_size=1)
+
+
+def test_graph_writer_creates_missing_output_directory(tmp_path: Path) -> None:
+    output = tmp_path / "nested" / "edges.csv"
+    write_graph_edges(output, [])
+    assert output.read_text(encoding="utf-8").startswith("source_id,target_id")

tests/test_similarity_search.py

@@ -6,7 +6,11 @@ from rdkit import Chem, DataStructs
 
 from scimesh.chemistry.dataset import DatasetStats, find_molecule_by_id, iter_valid_molecules
 from scimesh.chemistry.fingerprints import fingerprint
-from scimesh.workloads.similarity_search import SimilarityMatch, search_similar
+from scimesh.workloads.similarity_search import (
+    SimilarityMatch,
+    search_similar,
+    write_search_results,
+)
 
 
 def test_search_matches_full_sorting_and_skips_query_and_invalid(
@@ -56,3 +60,9 @@ def test_search_can_rank_and_filter_least_similar_molecules(
     assert result.matches == sorted(
         result.matches, key=lambda match: match.sort_key("less")
     )
+
+
+def test_search_writer_creates_missing_output_directory(tmp_path: Path) -> None:
+    output = tmp_path / "nested" / "results.csv"
+    write_search_results(output, [])
+    assert output.read_text(encoding="utf-8").startswith("rank,chembl_id")

tests/test_worker_daemon.py

@@ -11,9 +11,17 @@ import pytest
 from scimesh.worker.config import WorkerConfig
 from scimesh.worker.coordinator import CoordinatorTransientError
 from scimesh.worker.daemon import LeaseHeartbeat, WorkerDaemon
-from scimesh.worker.models import ClaimedTask, InputArtifact, ProducedArtifact, RunResult
+from scimesh.worker.models import (
+    ClaimedTask,
+    InputArtifact,
+    ProducedArtifact,
+    RegisteredWorker,
+    RunResult,
+    UploadedArtifact,
+)
 from scimesh.worker.artifacts import HttpArtifactClient, _SameOriginAuthRedirectHandler, _origin
 from scimesh.worker.runners import SciMeshRunner
+from scimesh.worker.transport import NoRedirectHandler
 
 
 class FakeCoordinator:
@@ -24,6 +32,11 @@ class FakeCoordinator:
         task, self.task = self.task, None
         return task
 
+    def register(
+        self, name: str, capabilities: tuple[str, ...], cpu_count: int, memory_mb: int | None
+    ) -> RegisteredWorker:
+        return RegisteredWorker("11111111-1111-4111-8111-111111111111", 15)
+
     def submit(self, task: ClaimedTask, payload: dict) -> None:
         self.submissions.append(payload)
 
@@ -42,9 +55,17 @@ class FakeArtifacts:
     def download(self, uri: str, destination: Path) -> None:
         destination.write_bytes(self.content)
 
-    def upload(self, task: ClaimedTask, worker_id: str, artifact: ProducedArtifact) -> str:
+    def upload(
+        self, task: ClaimedTask, worker_id: str, artifact: ProducedArtifact
+    ) -> UploadedArtifact:
         self.uploaded.append((task.task_id, worker_id, artifact.path))
-        return f"https://example.test/tasks/{task.task_id}/artifacts/{artifact.path.name}"
+        content = artifact.path.read_bytes()
+        return UploadedArtifact(
+            "22222222-2222-4222-8222-222222222222",
+            f"https://example.test/tasks/{task.task_id}/artifacts/{artifact.path.name}",
+            hashlib.sha256(content).hexdigest(),
+            len(content),
+        )
 
 class FakeRunner:
     def __init__(self) -> None:
@@ -75,9 +96,10 @@ def test_claims_runs_uploads_and_submits_csv(tmp_path: Path) -> None:
     assert runner.calls == 1
     assert len(artifacts.uploaded) == 1
     assert coordinator.heartbeats == [("task-1", 1, "worker-1")]
-    assert coordinator.submissions[0]["status"] == "completed"
+    assert "status" not in coordinator.submissions[0]
-    assert coordinator.submissions[0]["result"]["content_type"] == "text/csv"
+    assert coordinator.submissions[0]["result"] == {
-    assert coordinator.submissions[0]["result"]["uri"].startswith("https://example.test/tasks/task-1/artifacts/")
+        "artifact_id": "22222222-2222-4222-8222-222222222222"
+    }
 
 
 def test_no_task_does_not_create_directory(tmp_path: Path) -> None:
@@ -95,6 +117,14 @@ def test_bad_checksum_reports_failure_without_running(tmp_path: Path) -> None:
     assert not coordinator.submissions
 
 
+def test_directory_creation_failure_is_reported(tmp_path: Path) -> None:
+    content = b"input fixture"
+    worker, coordinator, _, _, config = daemon(tmp_path, make_task(content), content)
+    (config.work_dir / "task-1" / "1").mkdir(parents=True)
+    assert worker.run_once() is True
+    assert coordinator.failures[0]["error_code"] == "FileExistsError"
+
+
 def test_transient_claim_error_is_propagated_for_bounded_backoff(tmp_path: Path) -> None:
     class UnavailableCoordinator(FakeCoordinator):
         def claim(self, worker_id: str, capabilities: tuple[str, ...]) -> ClaimedTask | None:
@@ -123,6 +153,15 @@ def test_input_token_is_sent_only_to_the_coordinator_origin() -> None:
     assert client._auth_headers_for("https://bucket.example/presigned") == {}
 
 
+def test_relative_input_uri_is_resolved_against_the_coordinator() -> None:
+    client = HttpArtifactClient("https://coordinator.example/api", 10, "secret")
+    assert client._auth_headers_for("https://coordinator.example/tasks/1/input") == {
+        "Authorization": "Bearer secret"
+    }
+    # The coordinator's contract returns root-relative artifact paths.
+    assert client.coordinator_url == "https://coordinator.example/api"
+
+
 def test_redirect_to_external_storage_strips_authorization() -> None:
     handler = _SameOriginAuthRedirectHandler(_origin("https://coordinator.example"))
     source = Request(
@@ -133,6 +172,12 @@ def test_redirect_to_external_storage_strips_authorization() -> None:
     assert redirected.get_header("Authorization") is None
 
 
+def test_api_requests_never_follow_redirects() -> None:
+    handler = NoRedirectHandler()
+    request = Request("https://coordinator.example/tasks/claim", headers={"Authorization": "Bearer secret"})
+    assert handler.redirect_request(request, None, 302, "Found", {}, "https://other.example") is None
+
+
 def test_lease_is_renewed_while_a_runner_is_still_working(tmp_path: Path) -> None:
     content = b"input fixture"
     worker, coordinator, _, _, config = daemon(tmp_path, make_task(content), content)
@@ -184,3 +229,93 @@ def test_runner_maps_graph_and_smiles_search_parameters(tmp_path: Path, monkeypa
     assert "--block-size" in commands[0] and "42" in commands[0]
     assert "--max-rows" in commands[0] and "7" in commands[0]
     assert "--query-smiles" in commands[1] and "CCO" in commands[1]
+
+
+def test_runner_accepts_coordinator_workload_names(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    commands: list[list[str]] = []
+
+    def fake_run(command: list[str], **_: object) -> None:
+        commands.append(command)
+        output = Path(command[command.index("--output") + 1])
+        output.parent.mkdir(parents=True, exist_ok=True)
+        output.write_text("a,b\\n", encoding="utf-8")
+
+    monkeypatch.setattr("scimesh.worker.runners.subprocess.run", fake_run)
+    task = ClaimedTask(
+        "search", 1, "2026-07-30T00:00:00Z", "similarity_search",
+        InputArtifact("https://example/input", "a" * 64), {"query_smiles": "CCO"},
+    )
+    SciMeshRunner().run(task, tmp_path / "search")
+    assert commands[0][3] == "similarity-search"
+
+
+def test_claimed_task_rejects_path_traversal_and_invalid_metadata() -> None:
+    payload = {
+        "task_id": "../outside",
+        "attempt": 1,
+        "lease_expires_at": "2026-07-30T00:00:00Z",
+        "workload": "similarity-search",
+        "input": {"uri": "https://example.test/input", "sha256": "a" * 64},
+        "parameters": {},
+    }
+    with pytest.raises(ValueError, match="invalid claimed-task response"):
+        ClaimedTask.from_json(payload)
+
+    payload["task_id"] = "11111111-1111-4111-8111-111111111111"
+    payload["input"] = {"uri": "//outside.example/input", "sha256": "a" * 64}
+    with pytest.raises(ValueError, match="invalid claimed-task response"):
+        ClaimedTask.from_json(payload)
+
+    payload["input"] = {"uri": "/tasks/../outside/input", "sha256": "a" * 64}
+    with pytest.raises(ValueError, match="invalid claimed-task response"):
+        ClaimedTask.from_json(payload)
+
+
+def test_claimed_task_accepts_a_coordinator_relative_input_path() -> None:
+    task = ClaimedTask.from_json(
+        {
+            "task_id": "11111111-1111-4111-8111-111111111111",
+            "attempt": 1,
+            "lease_expires_at": "2026-07-30T00:00:00Z",
+            "workload": "similarity_search",
+            "input": {"uri": "/tasks/11111111-1111-4111-8111-111111111111/input", "sha256": "a" * 64},
+            "parameters": {},
+        }
+    )
+    assert task.input.uri.startswith("/tasks/")
+
+
+def test_uploaded_artifact_requires_complete_durable_metadata() -> None:
+    artifact = UploadedArtifact.from_json(
+        {
+            "artifact_id": "22222222-2222-4222-8222-222222222222",
+            "uri": "https://coordinator.example/artifacts/222/download",
+            "sha256": "a" * 64,
+            "size_bytes": 12,
+        }
+    )
+    assert artifact.size_bytes == 12
+    with pytest.raises(ValueError, match="artifact size_bytes"):
+        UploadedArtifact.from_json({"artifact_id": "missing"})
+
+
+def test_environment_overrides_allow_cli_only_configuration(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
+    monkeypatch.delenv("SCIMESH_COORDINATOR_URL", raising=False)
+    config = WorkerConfig.from_environment(
+        {
+            "coordinator_url": "https://coordinator.example",
+            "work_dir": tmp_path,
+            "worker_name": "test-worker",
+        }
+    )
+    assert config.coordinator_url == "https://coordinator.example"
+    assert config.worker_id is None
+    assert "similarity-search" in config.capabilities
+    assert "similarity_search" in config.capabilities
+
+
+def test_worker_registration_sets_returned_identity(tmp_path: Path) -> None:
+    worker, _, _, _, _ = daemon(tmp_path, None, b"")
+    worker._register_worker()
+    assert worker.worker_id == "11111111-1111-4111-8111-111111111111"
+    assert worker.config.heartbeat_interval == 15