Publish immutable remote commits

2026-08-10 20:05:24 +00:00
parent d6deccf3e8
commit 361dbb4ca8
15 changed files with 725 additions and 251 deletions
--- a/docs/internal/artifacts.md
+++ b/docs/internal/artifacts.md
@@ -102,10 +102,9 @@ restore, status and validation checks, and previous-cache planning.

 Core helpers:

- `LoadCurrentRunPointer`
- `LoadCurrentManifest`
 - `LoadCurrentState`
 - `ValidateCurrentStateIdentity`
+- `RemoteCommitManifest` and `CurrentCommitPointer`

 Typed missing-state errors:

@@ -133,6 +132,12 @@ Caller policy is intentionally outside artifacts helpers:
 - spool/cache paths;
 - S3 session/run/current-state key layout.

+New publication creates run-scoped immutable objects, including
+`runs/{run_id}/commit.json` and `runs/{run_id}/session-manifest.json`. The sole
+mutable selector is `current/commit-pointer.json`; readers verify its selected
+commit and declared object generations/checksums. Legacy current-pair loading
+is confined to `current_state_legacy.go` for migration only.
+
 Campaign, session, and Narratio run IDs are validated as portable opaque
 segments at configuration and artifact boundaries before they can be used in a
 workspace or S3 namespace. Previous-artifact destinations remain typed,
--- a/docs/internal/stage-publish.md
+++ b/docs/internal/stage-publish.md
@@ -16,8 +16,8 @@ Upload run/session outputs to object storage and atomically advance remote curre

 - uploaded invocation record and selected publish outputs;
 - uploaded durable previous-session cache files when present;
- updated remote current manifest; and
- remote current-run commit marker, written last.
+- immutable run-scoped commit manifest; and
+- current commit pointer, written last.

 Exact remote placement and the operator workflow belong in
 [Operations](../operations.md#publish-workflow).
@@ -40,7 +40,10 @@ Exact remote placement and the operator workflow belong in
 - selected artifact filter applies to configured artifact sources only.
 - locked outputs are skipped intentionally (including required ones).
 - optional missing outputs are skipped; required missing unlocked outputs fail.
- writes remote current manifest before current run pointer.
+- creates one complete immutable source-to-destination mapping before upload;
+- uploads and verifies every declared immutable object and the commit manifest;
+- updates `current/commit-pointer.json` exactly once, last; and
+- does not write the legacy `current/manifest.json` or `current/run_id.txt` pair.

 ## Metadata Signals

@@ -51,12 +54,13 @@ Includes counts/lists for:
 - skipped optional outputs
 - skipped unselected outputs
 - locked outputs
- current-state key paths
- `current_pointer_written`
+- remote commit and current-pointer key paths

 ## Invariants

- `current/run_id.txt` is the remote commit marker and is written last.
+- `current/commit-pointer.json` is the remote commit marker and is written last.
+- run files, selected outputs, previous-cache files, and the committed session
+  manifest are all declared by an immutable commit under the run prefix.
 - run and previous uploads contain only manifest-declared regular files opened
  from verified descriptors; symlinks, special files, replacement races, and
  undeclared entries are rejected or ignored before uploads begin.
--- a/docs/internal/workspace.md
+++ b/docs/internal/workspace.md
@@ -55,7 +55,8 @@ lock only while their context remains active, and report a release failure.
 Automatic post-publish cleanup:

 - only runs when publish actually executed and succeeded;
- requires `uploaded=true` and `current_pointer_written=true` metadata;
+- requires `uploaded=true`, a remote commit key, and a current commit-pointer
+  key in publish metadata;
 - consumes the resolved cleanup policy described in
  [Configuration](../config.md);
 - refuses unsafe deletes (root delete, out-of-root delete, and symlinked
--- a/docs/operations.md
+++ b/docs/operations.md
@@ -200,13 +200,15 @@ Publish commit model:

 - uploads eligible run files under `{session_prefix}/runs/{run_id}/`, excluding
  audio and the run-local Notarius staging bundle;
- uploads configured published outputs, including only explicitly configured
-  extraction lanes;
- uploads `previous/**` cache files when present;
- writes `current/manifest.json`;
- writes `current/run_id.txt` last.
+- uploads configured published outputs and `previous/**` cache files into the
+  same immutable run scope, including only explicitly configured extraction
+  lanes;
+- writes `{session_prefix}/runs/{run_id}/commit.json` after all declared
+  immutable objects are uploaded and verified; and
+- writes `{session_prefix}/current/commit-pointer.json` once, last.

-`current/run_id.txt` is the remote current-state commit marker.
+`current/commit-pointer.json` is the remote current-state commit marker. It
+selects exactly one immutable commit, which declares the complete object set.

 ## Remote Commit Migration

@@ -217,10 +219,10 @@ commit by version, checksum, size, and storage generation; committed artifacts
 are also checksum- and generation-bound. Readers accept this contract now and
 strictly reject mismatched or unknown data.

-The publish workflow above remains the legacy writer until its planned cutover.
 Legacy reads are limited to a coherent `current/manifest.json` and
-`current/run_id.txt` pair; a torn pair is rejected. New remote commit state does
-not carry local `current_pointer_written` metadata.
+`current/run_id.txt` pair; a torn pair is rejected. New publication does not
+write that pair and remote commit state does not carry local
+`current_pointer_written` metadata.

 ## Publish Locks

--- a/docs/policy/architecture.md
+++ b/docs/policy/architecture.md
@@ -167,13 +167,13 @@ contracts belong under [Integrations](../integrations/).
 ## Publish Commit Boundary

 Publish has one explicit remote commit boundary. A remote run becomes current
-only after Narratio has successfully uploaded the run record, required published
-outputs, `current/manifest.json`, and finally `current/run_id.txt`.
+only after Narratio has successfully uploaded its immutable run-scoped objects,
+the immutable commit manifest, and finally the current commit pointer.

-`current/run_id.txt` is the commit marker and must be written last. Failed,
-incomplete, skipped, or uncommitted publish attempts must not be presented as
-current remote state. Publish locks remain authoritative and are not bypassed by
-a forced run.
+`current/commit-pointer.json` is the sole mutable selector and must be written
+exactly once, last. Failed, incomplete, skipped, or uncommitted publish attempts
+must not be presented as current remote state. Publish locks remain authoritative
+and are not bypassed by a forced run.

 Automatic local cleanup is permitted only after a successful publish commit,
 only when explicitly configured, and only through the path-safety guardrails.
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -29,7 +29,7 @@ All stages are pending when this plan is created.
 | 11 | Make manifest and run identity singular | COR-001, TST-006 | Completed |
 | 12 | Centralize handled terminal-failure persistence | RSK-001, TST-002, SIM-001, COM-001 | Completed |
 | 13 | Introduce the immutable remote-commit model and legacy boundary | ARC-003 | Completed |
-| 14 | Publish through immutable commits and canonical mappings | COR-004, COR-011, DUP-002, TST-004 | Pending |
+| 14 | Publish through immutable commits and canonical mappings | COR-004, COR-011, DUP-002, TST-004 | Completed |
 | 15 | Make remote locks generation-safe and harden pagination | RSK-005, RSK-014 | Pending |
 | 16 | Persist retryable post-commit cleanup state | COR-006, COR-007 | Pending |
 | 17 | Bind restore/status to a committed snapshot and reject conflicts | COR-008, COR-009, TST-005 | Pending |
--- a/internal/adapters/storage/fake.go
+++ b/internal/adapters/storage/fake.go
@@ -2,6 +2,8 @@ package storage

 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"fmt"
 	"io"
 	"os"
@@ -21,6 +23,7 @@ type FakeBackend struct {
 	DownloadErr error
 	UploadErr   error
 	ExistsErr   error
+	UploadHook  func(FakeUploadCall) error
 }

 // FakeUploadCall captures one upload invocation in call order.
@@ -54,6 +57,9 @@ func (f *FakeBackend) SeedObject(obj FakeObject) {
 	obj.Key = key
 	obj.Data = append([]byte(nil), obj.Data...)
 	obj.Metadata = copyMetadata(obj.Metadata)
+	if obj.ETag == "" {
+		obj.ETag = fakeObjectETag(obj.Data)
+	}
 	f.Objects[key] = obj
 }

@@ -175,14 +181,20 @@ func (f *FakeBackend) uploadReader(ctx context.Context, source io.Reader, key st
 	}

 	normalizedKey := normalizeObjectKey(key)
-	f.Uploads = append(f.Uploads, FakeUploadCall{
+	call := FakeUploadCall{
 		LocalPath: localPath,
 		Key:       normalizedKey,
 		Options: UploadOptions{
 			Metadata:    copyMetadata(opts.Metadata),
 			ContentType: opts.ContentType,
 		},
-	})
+	}
+	f.Uploads = append(f.Uploads, call)
+	if f.UploadHook != nil {
+		if err := f.UploadHook(call); err != nil {
+			return ObjectInfo{}, err
+		}
+	}
 	now := time.Now().UTC()
 	obj := FakeObject{
 		Key:          normalizedKey,
@@ -194,10 +206,16 @@ func (f *FakeBackend) uploadReader(ctx context.Context, source io.Reader, key st
 	return ObjectInfo{
 		Key:          normalizedKey,
 		Size:         int64(len(data)),
+		ETag:         fakeObjectETag(data),
 		LastModified: &now,
 	}, nil
 }

+func fakeObjectETag(data []byte) string {
+	sum := sha256.Sum256(data)
+	return hex.EncodeToString(sum[:])
+}
+
 // Exists checks object presence.
 func (f *FakeBackend) Exists(ctx context.Context, key string) (bool, error) {
 	if err := ctx.Err(); err != nil {
--- a/internal/app/post_publish_cleanup.go
+++ b/internal/app/post_publish_cleanup.go
@@ -144,11 +144,11 @@ func publishCleanupEligible(cfg *config.Config, sr *manifest.StageRecord) (bool,
 	if uploaded, _ := sr.Metadata["uploaded"].(bool); !uploaded {
 		return false, "publish did not upload run record"
 	}
-	if pointer, _ := sr.Metadata["current_pointer_written"].(bool); !pointer {
-		return false, "publish did not write current pointer"
+	if strings.TrimSpace(asString(sr.Metadata["remote_commit_key"])) == "" {
+		return false, "publish remote commit key is missing"
 	}
-	if strings.TrimSpace(asString(sr.Metadata["current_run_id_key"])) == "" {
-		return false, "publish current run pointer key is missing"
+	if strings.TrimSpace(asString(sr.Metadata["current_commit_pointer_key"])) == "" {
+		return false, "publish current commit pointer key is missing"
 	}
 	return true, ""
 }
--- a/internal/app/post_publish_cleanup_test.go
+++ b/internal/app/post_publish_cleanup_test.go
@@ -25,10 +25,10 @@ func (publishSuccessStage) Name() string           { return "publish" }
 func (publishSuccessStage) Declares() stage.IODecl { return stage.IODecl{} }
 func (s publishSuccessStage) Run(_ context.Context, _ *stage.Env, _ *manifest.Manifest) (*stage.StageResult, error) {
 	md := map[string]any{
-		"stage":                   "publish",
-		"uploaded":                true,
-		"current_pointer_written": true,
-		"current_run_id_key":      "dnd/campaigns/sample-campaign/sessions/2026-05-03/current/run_id.txt",
+		"stage":                      "publish",
+		"uploaded":                   true,
+		"remote_commit_key":          "dnd/campaigns/sample-campaign/sessions/2026-05-03/runs/20260519T010203Z-a1b2c3d4/commit.json",
+		"current_commit_pointer_key": "dnd/campaigns/sample-campaign/sessions/2026-05-03/current/commit-pointer.json",
 	}
 	for k, v := range s.metadata {
 		md[k] = v
@@ -130,12 +130,12 @@ func TestPostPublishCleanupNotRunWhenPublishSkipped(t *testing.T) {
 	assertExists(t, seed.runWorkDir)
 }

-func TestPostPublishCleanupNotRunWhenCurrentPointerMissing(t *testing.T) {
+func TestPostPublishCleanupNotRunWhenCommitPointerMissing(t *testing.T) {
 	cfg, seed := cleanupFixtureConfig(t)
 	cfg.Pipeline.Spool.DeleteAudioAfterPublish = true
 	cfg.Pipeline.Workspace.CleanupAfterPublish = true

-	if _, err := executeStages(context.Background(), cfg, []stage.Stage{publishSuccessStage{metadata: map[string]any{"current_pointer_written": false}}}, RunOptions{Env: &Env{ObjectStore: &storage.FakeBackend{}}}); err != nil {
+	if _, err := executeStages(context.Background(), cfg, []stage.Stage{publishSuccessStage{metadata: map[string]any{"current_commit_pointer_key": ""}}}, RunOptions{Env: &Env{ObjectStore: &storage.FakeBackend{}}}); err != nil {
 		t.Fatalf("executeStages() error = %v", err)
 	}

@@ -216,11 +216,11 @@ func TestPostPublishCleanupNotRunWhenOutputIsMissing(t *testing.T) {
 	assertExists(t, artifacts.SessionRunRootForCampaign(cfg.Pipeline.Workspace.Root, cfg.Session.Campaign, cfg.Session.SessionID, runID))
 }

-func TestPostPublishCleanupNotRunWhenCurrentManifestUploadFails(t *testing.T) {
+func TestPostPublishCleanupNotRunWhenCommittedManifestUploadFails(t *testing.T) {
 	cfg, seed, _ := publishStageCleanupFixture(t)
 	cfg.Pipeline.Spool.DeleteAudioAfterPublish = true
 	cfg.Pipeline.Workspace.CleanupAfterPublish = true
-	failKey := seed.sessionPrefix + "current/manifest.json"
+	failKey := artifacts.S3RunSessionManifestKey(seed.sessionPrefix, seed.runID)

 	publishStageImpl, err := stage.Select("publish")
 	if err != nil {
@@ -229,19 +229,19 @@ func TestPostPublishCleanupNotRunWhenCurrentManifestUploadFails(t *testing.T) {
 	_, err = executeStages(context.Background(), cfg, []stage.Stage{publishStageImpl}, RunOptions{
 		Env: &Env{ObjectStore: &failKeyStore{delegate: &storage.FakeBackend{}, failKey: failKey}},
 	})
-	if err == nil || !strings.Contains(err.Error(), "current manifest") {
-		t.Fatalf("executeStages() error = %v, want current-manifest failure", err)
+	if err == nil || !strings.Contains(err.Error(), "immutable object") {
+		t.Fatalf("executeStages() error = %v, want committed-manifest failure", err)
 	}

 	assertExists(t, seed.spoolAudioDir)
 	assertExists(t, seed.runWorkDir)
 }

-func TestPostPublishCleanupNotRunWhenCurrentPointerUploadFails(t *testing.T) {
+func TestPostPublishCleanupNotRunWhenCommitPointerUploadFails(t *testing.T) {
 	cfg, seed, _ := publishStageCleanupFixture(t)
 	cfg.Pipeline.Spool.DeleteAudioAfterPublish = true
 	cfg.Pipeline.Workspace.CleanupAfterPublish = true
-	failKey := seed.sessionPrefix + "current/run_id.txt"
+	failKey := artifacts.S3CurrentCommitPointerKey(seed.sessionPrefix)

 	publishStageImpl, err := stage.Select("publish")
 	if err != nil {
@@ -250,8 +250,8 @@ func TestPostPublishCleanupNotRunWhenCurrentPointerUploadFails(t *testing.T) {
 	_, err = executeStages(context.Background(), cfg, []stage.Stage{publishStageImpl}, RunOptions{
 		Env: &Env{ObjectStore: &failKeyStore{delegate: &storage.FakeBackend{}, failKey: failKey}},
 	})
-	if err == nil || !strings.Contains(err.Error(), "current run pointer") {
-		t.Fatalf("executeStages() error = %v, want current-run-pointer failure", err)
+	if err == nil || !strings.Contains(err.Error(), "current commit pointer") {
+		t.Fatalf("executeStages() error = %v, want current-commit-pointer failure", err)
 	}

 	assertExists(t, seed.spoolAudioDir)
@@ -259,6 +259,7 @@ func TestPostPublishCleanupNotRunWhenCurrentPointerUploadFails(t *testing.T) {
 }

 type cleanupSeed struct {
+	runID             string
 	runWorkDir        string
 	otherRunDir       string
 	spoolAudioDir     string
@@ -312,6 +313,7 @@ func cleanupFixtureConfig(t *testing.T) (*config.Config, cleanupSeed) {
 	}

 	return cfg, cleanupSeed{
+		runID:             runID,
 		runWorkDir:        runWorkDir,
 		otherRunDir:       otherRunDir,
 		spoolAudioDir:     spoolAudioDir,
--- a/internal/artifacts/remote_commit.go
+++ b/internal/artifacts/remote_commit.go
@@ -19,6 +19,7 @@ type RemoteArtifactType string
 const (
 	RemoteArtifactTypeSessionManifest  RemoteArtifactType = "session_manifest"
 	RemoteArtifactTypeRunManifest      RemoteArtifactType = "run_manifest"
+	RemoteArtifactTypeRunFile          RemoteArtifactType = "run_file"
 	RemoteArtifactTypePublishedOutput  RemoteArtifactType = "published_output"
 	RemoteArtifactTypePreviousArtifact RemoteArtifactType = "previous_artifact"
 )
@@ -68,15 +69,38 @@ func (m RemoteCommitManifest) Validate() error {
 		return fmt.Errorf("remote commit artifacts are required")
 	}

-	destinations := make(map[string]struct{}, len(m.Artifacts))
+	if err := ValidateRemoteArtifactMapping(m.Artifacts); err != nil {
+		return err
+	}
 	for index, artifact := range m.Artifacts {
 		if err := artifact.Validate(); err != nil {
 			return fmt.Errorf("remote commit artifact %d: %w", index, err)
 		}
+	}
+	return nil
+}
+
+// ValidateRemoteArtifactMapping verifies that source and destination identities
+// form one unambiguous immutable-object mapping.
+func ValidateRemoteArtifactMapping(artifacts []RemoteArtifact) error {
+	if len(artifacts) == 0 {
+		return fmt.Errorf("remote commit artifacts are required")
+	}
+	destinations := make(map[string]struct{}, len(artifacts))
+	sources := make(map[string]struct{}, len(artifacts))
+	for index, artifact := range artifacts {
+		if err := validateRemoteArtifactIdentity(artifact); err != nil {
+			return fmt.Errorf("remote commit artifact %d: %w", index, err)
+		}
 		if _, exists := destinations[artifact.DestinationKey]; exists {
 			return fmt.Errorf("remote commit declares duplicate destination %q", artifact.DestinationKey)
 		}
 		destinations[artifact.DestinationKey] = struct{}{}
+		sourceKey := string(artifact.Type) + "\x00" + artifact.Source
+		if _, exists := sources[sourceKey]; exists {
+			return fmt.Errorf("remote commit declares ambiguous %s source %q", artifact.Type, artifact.Source)
+		}
+		sources[sourceKey] = struct{}{}
 	}
 	return nil
 }
@@ -98,16 +122,8 @@ func (m RemoteCommitManifest) ValidateForSessionPrefix(sessionPrefix string) err
 }

 func (a RemoteArtifact) Validate() error {
-	switch a.Type {
-	case RemoteArtifactTypeSessionManifest, RemoteArtifactTypeRunManifest, RemoteArtifactTypePublishedOutput, RemoteArtifactTypePreviousArtifact:
-	default:
-		return fmt.Errorf("unsupported artifact type %q", a.Type)
-	}
-	if strings.TrimSpace(a.Source) == "" {
-		return fmt.Errorf("source is required")
-	}
-	if err := validateRemoteObjectKey(a.DestinationKey); err != nil {
-		return fmt.Errorf("destination key: %w", err)
+	if err := validateRemoteArtifactIdentity(a); err != nil {
+		return err
 	}
 	if err := validateSHA256(a.SHA256); err != nil {
 		return fmt.Errorf("sha256: %w", err)
@@ -121,6 +137,21 @@ func (a RemoteArtifact) Validate() error {
 	return nil
 }

+func validateRemoteArtifactIdentity(a RemoteArtifact) error {
+	switch a.Type {
+	case RemoteArtifactTypeSessionManifest, RemoteArtifactTypeRunManifest, RemoteArtifactTypeRunFile, RemoteArtifactTypePublishedOutput, RemoteArtifactTypePreviousArtifact:
+	default:
+		return fmt.Errorf("unsupported artifact type %q", a.Type)
+	}
+	if strings.TrimSpace(a.Source) == "" {
+		return fmt.Errorf("source is required")
+	}
+	if err := validateRemoteObjectKey(a.DestinationKey); err != nil {
+		return fmt.Errorf("destination key: %w", err)
+	}
+	return nil
+}
+
 func (p CurrentCommitPointer) Validate() error {
 	if p.FormatVersion != RemoteCommitFormatVersion {
 		return fmt.Errorf("unsupported current commit pointer format version %d", p.FormatVersion)
--- a/internal/artifacts/s3_keys.go
+++ b/internal/artifacts/s3_keys.go
@@ -64,6 +64,12 @@ func S3RunCommitKey(sessionPrefix, runID string) string {
 	return path.Join(strings.TrimSuffix(S3RunPrefix(sessionPrefix, runID), "/"), config.S3CommitFile)
 }

+// S3RunSessionManifestKey returns the immutable session-manifest snapshot key for one run.
+// Format: {session_prefix}/runs/{run_id}/session-manifest.json
+func S3RunSessionManifestKey(sessionPrefix, runID string) string {
+	return path.Join(strings.TrimSuffix(S3RunPrefix(sessionPrefix, runID), "/"), config.S3SessionSnapshotFile)
+}
+
 // S3CurrentCommitPointerKey returns the sole mutable selector for a committed run.
 // Format: {session_prefix}/current/commit-pointer.json
 func S3CurrentCommitPointerKey(sessionPrefix string) string {
--- a/internal/artifacts/s3_keys_test.go
+++ b/internal/artifacts/s3_keys_test.go
@@ -35,6 +35,9 @@ func TestS3KeyConstruction(t *testing.T) {
 	if got, want := S3RunCommitKey(sessionPrefix, runID), wantRunPrefix+"commit.json"; got != want {
 		t.Fatalf("commit key = %q, want %q", got, want)
 	}
+	if got, want := S3RunSessionManifestKey(sessionPrefix, runID), wantRunPrefix+"session-manifest.json"; got != want {
+		t.Fatalf("session manifest key = %q, want %q", got, want)
+	}

 	runPointer := S3CurrentRunPointerKey(sessionPrefix)
 	if runPointer != "dnd/campaigns/forsaken/sessions/2026-04-19/current/run_id.txt" {
--- a/internal/config/defaults.go
+++ b/internal/config/defaults.go
@@ -83,14 +83,15 @@ const (
 	PathTranscriptFinal        = artifactmodel.TranscriptPathFinal
 	PathTranscriptFinalTrimmed = artifactmodel.TranscriptPathFinalTrimmed

-	S3CampaignsSegment  = "campaigns"
-	S3SessionsSegment   = "sessions"
-	S3RunsSegment       = "runs"
-	S3CurrentSegment    = "current"
-	S3ManifestFile      = "manifest.json"
-	S3RunIDFile         = "run_id.txt"
-	S3CommitFile        = "commit.json"
-	S3CommitPointerFile = "commit-pointer.json"
+	S3CampaignsSegment    = "campaigns"
+	S3SessionsSegment     = "sessions"
+	S3RunsSegment         = "runs"
+	S3CurrentSegment      = "current"
+	S3ManifestFile        = "manifest.json"
+	S3RunIDFile           = "run_id.txt"
+	S3CommitFile          = "commit.json"
+	S3CommitPointerFile   = "commit-pointer.json"
+	S3SessionSnapshotFile = "session-manifest.json"
 )

 // DefaultPublishOutputs defines the default publish output rules.
--- a/internal/stage/publish.go
+++ b/internal/stage/publish.go
@@ -1,6 +1,7 @@
 package stage

 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
@@ -12,7 +13,6 @@ import (
 	"path/filepath"
 	"sort"
 	"strings"
-	"time"

 	"gitea.maximumdirect.net/eric/narratio/internal/adapters/storage"
 	"gitea.maximumdirect.net/eric/narratio/internal/artifactpolicy"
@@ -59,22 +59,20 @@ func (publishStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 	if publishDisabled(env) {
 		return &StageResult{
 			Metadata: map[string]any{
-				"stage":                   "publish",
-				"skipped":                 true,
-				"publish_enabled":         false,
-				"audio_upload_skipped":    true,
-				"current_pointer_written": false,
+				"stage":                "publish",
+				"skipped":              true,
+				"publish_enabled":      false,
+				"audio_upload_skipped": true,
 			},
 		}, nil
 	}
 	if publishRunUploadDisabled(env) {
 		return &StageResult{
 			Metadata: map[string]any{
-				"stage":                   "publish",
-				"skipped":                 true,
-				"upload_run_enabled":      false,
-				"audio_upload_skipped":    true,
-				"current_pointer_written": false,
+				"stage":                "publish",
+				"skipped":              true,
+				"upload_run_enabled":   false,
+				"audio_upload_skipped": true,
 			},
 		}, nil
 	}
@@ -86,10 +84,11 @@ func (publishStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 		return nil, fmt.Errorf("publish: remote object store backend is required when publish run upload is enabled")
 	}

-	runRoot, err := resolvePublishRunRoot(env, m)
+	runManifestPath, err := resolvePublishRunManifestPath(env, m)
 	if err != nil {
-		return nil, fmt.Errorf("publish: resolve run root: %w", err)
+		return nil, fmt.Errorf("publish: resolve run manifest path: %w", err)
 	}
+	runRoot := filepath.Dir(runManifestPath)
 	runRootInfo, err := os.Lstat(runRoot)
 	if err != nil {
 		return nil, fmt.Errorf("publish: run root %q: %w", runRoot, err)
@@ -115,7 +114,7 @@ func (publishStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 		return nil, fmt.Errorf("publish: run id is required")
 	}

-	runManifestFile, err := fileops.OpenConfinedRegularFile(runRoot, "manifest.json")
+	runManifestFile, err := fileops.OpenConfinedRegularFile(runRoot, filepath.Base(runManifestPath))
 	if err != nil {
 		return nil, fmt.Errorf("publish: open run manifest: %w", err)
 	}
@@ -170,72 +169,83 @@ func (publishStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 		env.Config.Pipeline.Publish.Outputs,
 		env.Config.Pipeline.Publish.Locks,
 		env.SelectedArtifactKeys,
-		sessionPrefix,
+		runPrefix,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("publish: resolve publish output rules: %w", err)
 	}
-	runUploaded := make([]string, 0, len(runFiles))
-	for index, file := range runFiles {
-		key := artifacts.S3RunRelativeDestinationKey(runPrefix, file.RelativePath)
-		if _, err := uploader.UploadReader(ctx, runSources[index], key, storage.UploadOptions{}); err != nil {
-			return nil, fmt.Errorf("publish: upload run file %q to %q: %w", file.RelativePath, key, err)
-		}
-		runUploaded = append(runUploaded, file.RelativePath)
-	}

-	publishedUploaded := make([]string, 0, len(publishOutputs))
-	for _, publishedOutput := range publishOutputs {
-		key := artifacts.S3PublishedOutputKey(sessionPrefix, publishedOutput.Dest)
-		if _, err := env.ObjectStore.Upload(ctx, publishedOutput.LocalPath, key, storage.UploadOptions{}); err != nil {
-			return nil, fmt.Errorf("publish: upload published output source %q to %q: %w", publishedOutput.Source, key, err)
-		}
-		publishedUploaded = append(publishedUploaded, publishedOutput.Dest)
-	}
+	runUploaded := publishUploadPaths(runFiles)
+	publishedUploaded := publishOutputPaths(publishOutputs)
+	previousUploaded := publishUploadPaths(previousFiles)
+	commitKey := artifacts.S3RunCommitKey(sessionPrefix, runID)
+	pointerKey := artifacts.S3CurrentCommitPointerKey(sessionPrefix)

-	previousUploaded := make([]string, 0, len(previousFiles))
-	for index, file := range previousFiles {
-		key := artifacts.S3PublishedOutputKey(sessionPrefix, file.RelativePath)
-		if _, err := uploader.UploadReader(ctx, previousSources[index], key, storage.UploadOptions{}); err != nil {
-			return nil, fmt.Errorf("publish: upload previous file %q to %q: %w", file.RelativePath, key, err)
-		}
-		previousUploaded = append(previousUploaded, file.RelativePath)
+	transfers, err := buildPublishTransferPlan(runPrefix, runFiles, runSources, previousFiles, previousSources, publishOutputs)
+	if err != nil {
+		return nil, fmt.Errorf("publish: build immutable upload mapping: %w", err)
 	}
+	defer func() { closePublishTransfers(transfers) }()

-	currentManifestKey, currentRunPointerKey := artifacts.ResolveCurrentStateKeys(sessionPrefix)
-	manifestTempPath, err := writeCurrentManifestSnapshot(m, publishMetadataPreview(
+	manifestTempPath, err := writeCommittedSessionManifest(m, publishMetadata(
 		bucket,
 		runPrefix,
-		sessionPrefix,
 		runUploaded,
 		publishedUploaded,
 		previousUploaded,
 		skippedOptionalOutputs,
 		skippedUnselectedOutputs,
 		lockedOutputs,
-		currentManifestKey,
+		commitKey,
+		pointerKey,
 	))
 	if err != nil {
-		return nil, fmt.Errorf("publish: build current manifest snapshot: %w", err)
+		return nil, fmt.Errorf("publish: build committed session manifest: %w", err)
 	}
-	defer func() { _ = os.Remove(manifestTempPath) }()
-
-	if _, err := env.ObjectStore.Upload(ctx, manifestTempPath, currentManifestKey, storage.UploadOptions{
-		ContentType: "application/json",
-	}); err != nil {
-		return nil, fmt.Errorf("publish: upload current manifest to %q: %w", currentManifestKey, err)
+	if err := appendCommittedSessionManifest(&transfers, manifestTempPath, artifacts.S3RunSessionManifestKey(sessionPrefix, runID)); err != nil {
+		return nil, fmt.Errorf("publish: add committed session manifest: %w", err)
+	}
+	if err := validatePublishTransferPlan(transfers, commitKey); err != nil {
+		return nil, fmt.Errorf("publish: validate immutable upload mapping: %w", err)
 	}

-	runIDTempPath, err := writeCurrentRunIDPointer(runID)
+	commit := artifacts.RemoteCommitManifest{
+		FormatVersion: artifacts.RemoteCommitFormatVersion,
+		Campaign:      strings.TrimSpace(m.Campaign),
+		SessionID:     strings.TrimSpace(m.SessionID),
+		RunID:         runID,
+		Artifacts:     make([]artifacts.RemoteArtifact, 0, len(transfers)),
+	}
+	for index := range transfers {
+		artifact, err := uploadVerifiedPublishTransfer(ctx, env.ObjectStore, uploader, &transfers[index])
+		if err != nil {
+			return nil, fmt.Errorf("publish: upload immutable object %q: %w", transfers[index].Artifact.DestinationKey, err)
+		}
+		commit.Artifacts = append(commit.Artifacts, artifact)
+	}
+	commitData, err := artifacts.EncodeRemoteCommitManifest(commit)
 	if err != nil {
-		return nil, fmt.Errorf("publish: build current run id pointer: %w", err)
+		return nil, fmt.Errorf("publish: encode immutable commit: %w", err)
 	}
-	defer func() { _ = os.Remove(runIDTempPath) }()
-
-	if _, err := env.ObjectStore.Upload(ctx, runIDTempPath, currentRunPointerKey, storage.UploadOptions{
-		ContentType: "text/plain; charset=utf-8",
-	}); err != nil {
-		return nil, fmt.Errorf("publish: upload current run pointer to %q: %w", currentRunPointerKey, err)
+	commitInfo, err := uploadVerifiedPublishBytes(ctx, env.ObjectStore, uploader, commitKey, commitData, "application/json")
+	if err != nil {
+		return nil, fmt.Errorf("publish: upload immutable commit %q: %w", commitKey, err)
+	}
+	pointerData, err := artifacts.EncodeCurrentCommitPointer(artifacts.CurrentCommitPointer{
+		FormatVersion:    artifacts.RemoteCommitFormatVersion,
+		Campaign:         commit.Campaign,
+		SessionID:        commit.SessionID,
+		RunID:            commit.RunID,
+		CommitKey:        commitKey,
+		CommitSHA256:     publishSHA256(commitData),
+		CommitSize:       int64(len(commitData)),
+		CommitGeneration: commitInfo.ETag,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("publish: encode current commit pointer: %w", err)
+	}
+	if _, err := uploader.UploadReader(ctx, bytes.NewReader(pointerData), pointerKey, storage.UploadOptions{ContentType: "application/json"}); err != nil {
+		return nil, fmt.Errorf("publish: update current commit pointer %q: %w", pointerKey, err)
 	}

 	return &StageResult{
@@ -254,9 +264,8 @@ func (publishStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 			"skipped_unselected_outputs": skippedUnselectedOutputMetadata(skippedUnselectedOutputs),
 			"locked_output_count":        len(lockedOutputs),
 			"locked_outputs":             lockedOutputMetadata(lockedOutputs),
-			"current_manifest_key":       currentManifestKey,
-			"current_run_id_key":         currentRunPointerKey,
-			"current_pointer_written":    true,
+			"remote_commit_key":          commitKey,
+			"current_commit_pointer_key": pointerKey,
 			"audio_upload_skipped":       true,
 		},
 	}, nil
@@ -270,6 +279,12 @@ type publishOutput struct {
 	Provenance string
 }

+type publishTransfer struct {
+	Artifact      artifacts.RemoteArtifact
+	Source        *os.File
+	TemporaryPath string
+}
+
 type publishLockedOutput struct {
 	Source     string
 	Dest       string
@@ -286,6 +301,292 @@ type publishSkippedUnselectedOutput struct {
 	Required bool
 }

+func buildPublishTransferPlan(
+	runPrefix string,
+	runFiles []publishUploadFile,
+	runSources []*os.File,
+	previousFiles []publishUploadFile,
+	previousSources []*os.File,
+	publishOutputs []publishOutput,
+) ([]publishTransfer, error) {
+	if len(runFiles) != len(runSources) || len(previousFiles) != len(previousSources) {
+		return nil, fmt.Errorf("verified publish sources do not match their declared files")
+	}
+	transfers := make([]publishTransfer, 0, len(runFiles)+len(previousFiles)+len(publishOutputs))
+	add := func(artifact artifacts.RemoteArtifact, source *os.File) error {
+		if source == nil {
+			return fmt.Errorf("source for %q is required", artifact.DestinationKey)
+		}
+		transfers = append(transfers, publishTransfer{Artifact: artifact, Source: source})
+		return nil
+	}
+	for index, file := range runFiles {
+		artifactType := artifacts.RemoteArtifactTypeRunFile
+		source := "run:" + file.RelativePath
+		if file.RelativePath == config.S3ManifestFile {
+			artifactType = artifacts.RemoteArtifactTypeRunManifest
+			source = "run.manifest"
+		}
+		if err := add(artifacts.RemoteArtifact{
+			Type:           artifactType,
+			Source:         source,
+			DestinationKey: artifacts.S3RunRelativeDestinationKey(runPrefix, file.RelativePath),
+		}, runSources[index]); err != nil {
+			closePublishTransfers(transfers)
+			return nil, err
+		}
+	}
+	for index, file := range previousFiles {
+		if err := add(artifacts.RemoteArtifact{
+			Type:           artifacts.RemoteArtifactTypePreviousArtifact,
+			Source:         "previous:" + file.SourceRelativePath,
+			DestinationKey: artifacts.S3RunRelativeDestinationKey(runPrefix, file.RelativePath),
+		}, previousSources[index]); err != nil {
+			closePublishTransfers(transfers)
+			return nil, err
+		}
+	}
+	for _, output := range publishOutputs {
+		source, err := openPublishOutputSource(output.LocalPath)
+		if err != nil {
+			closePublishTransfers(transfers)
+			return nil, fmt.Errorf("open output source %q: %w", output.Source, err)
+		}
+		if err := add(artifacts.RemoteArtifact{
+			Type:           artifacts.RemoteArtifactTypePublishedOutput,
+			Source:         output.Source,
+			DestinationKey: publishOutputRemoteKey(runPrefix, output.Dest),
+		}, source); err != nil {
+			_ = source.Close()
+			closePublishTransfers(transfers)
+			return nil, err
+		}
+	}
+	sort.Slice(transfers, func(i, j int) bool {
+		return transfers[i].Artifact.DestinationKey < transfers[j].Artifact.DestinationKey
+	})
+	return transfers, nil
+}
+
+func appendCommittedSessionManifest(transfers *[]publishTransfer, localPath, destinationKey string) error {
+	if transfers == nil {
+		return fmt.Errorf("transfer plan is required")
+	}
+	source, err := os.Open(localPath)
+	if err != nil {
+		return err
+	}
+	*transfers = append(*transfers, publishTransfer{
+		Artifact: artifacts.RemoteArtifact{
+			Type:           artifacts.RemoteArtifactTypeSessionManifest,
+			Source:         "session.manifest",
+			DestinationKey: destinationKey,
+		},
+		Source:        source,
+		TemporaryPath: localPath,
+	})
+	sort.Slice(*transfers, func(i, j int) bool {
+		return (*transfers)[i].Artifact.DestinationKey < (*transfers)[j].Artifact.DestinationKey
+	})
+	return nil
+}
+
+func validatePublishTransferPlan(transfers []publishTransfer, commitKey string) error {
+	artifactsToUpload := make([]artifacts.RemoteArtifact, 0, len(transfers))
+	for _, transfer := range transfers {
+		if transfer.Artifact.DestinationKey == commitKey {
+			return fmt.Errorf("artifact destination %q is reserved for the immutable commit", commitKey)
+		}
+		artifactsToUpload = append(artifactsToUpload, transfer.Artifact)
+	}
+	return artifacts.ValidateRemoteArtifactMapping(artifactsToUpload)
+}
+
+func openPublishOutputSource(localPath string) (*os.File, error) {
+	path := filepath.Clean(strings.TrimSpace(localPath))
+	if path == "" || path == "." {
+		return nil, fmt.Errorf("local path is required")
+	}
+	return fileops.OpenConfinedRegularFile(filepath.Dir(path), filepath.Base(path))
+}
+
+func publishOutputRemoteKey(runPrefix, destination string) string {
+	return artifacts.S3RunRelativeDestinationKey(runPrefix, filepath.ToSlash(filepath.Join("published", destination)))
+}
+
+func uploadVerifiedPublishTransfer(
+	ctx context.Context,
+	store storage.ObjectStore,
+	uploader storage.ReaderUploader,
+	transfer *publishTransfer,
+) (artifacts.RemoteArtifact, error) {
+	if transfer == nil || transfer.Source == nil {
+		return artifacts.RemoteArtifact{}, fmt.Errorf("transfer source is required")
+	}
+	if err := preparePublishTransfer(transfer); err != nil {
+		return artifacts.RemoteArtifact{}, err
+	}
+	if existing, found, err := verifyExistingImmutableObject(ctx, store, transfer.Artifact.DestinationKey, transfer.Artifact.SHA256, transfer.Artifact.Size); err != nil {
+		return artifacts.RemoteArtifact{}, err
+	} else if found {
+		transfer.Artifact.Generation = existing.ETag
+		return transfer.Artifact, nil
+	}
+	info, err := uploader.UploadReader(ctx, transfer.Source, transfer.Artifact.DestinationKey, storage.UploadOptions{})
+	if err != nil {
+		return artifacts.RemoteArtifact{}, err
+	}
+	verified, err := verifyPublishedObject(ctx, store, transfer.Artifact.DestinationKey, transfer.Artifact.Size, info.ETag)
+	if err != nil {
+		return artifacts.RemoteArtifact{}, err
+	}
+	transfer.Artifact.Generation = verified.ETag
+	return transfer.Artifact, nil
+}
+
+func uploadVerifiedPublishBytes(
+	ctx context.Context,
+	store storage.ObjectStore,
+	uploader storage.ReaderUploader,
+	key string,
+	data []byte,
+	contentType string,
+) (storage.ObjectInfo, error) {
+	checksum := publishSHA256(data)
+	if existing, found, err := verifyExistingImmutableObject(ctx, store, key, checksum, int64(len(data))); err != nil {
+		return storage.ObjectInfo{}, err
+	} else if found {
+		return existing, nil
+	}
+	info, err := uploader.UploadReader(ctx, bytes.NewReader(data), key, storage.UploadOptions{ContentType: contentType})
+	if err != nil {
+		return storage.ObjectInfo{}, err
+	}
+	return verifyPublishedObject(ctx, store, key, int64(len(data)), info.ETag)
+}
+
+func verifyExistingImmutableObject(ctx context.Context, store storage.ObjectStore, key, wantSHA256 string, wantSize int64) (storage.ObjectInfo, bool, error) {
+	exists, err := store.Exists(ctx, key)
+	if err != nil {
+		return storage.ObjectInfo{}, false, fmt.Errorf("check immutable object %q: %w", key, err)
+	}
+	if !exists {
+		return storage.ObjectInfo{}, false, nil
+	}
+	path, err := storage.DownloadObjectToTemp(ctx, store, key, "narratio-verify-immutable-*.bin")
+	if err != nil {
+		return storage.ObjectInfo{}, false, fmt.Errorf("download existing immutable object %q: %w", key, err)
+	}
+	defer func() { _ = os.Remove(path) }()
+	file, err := os.Open(path)
+	if err != nil {
+		return storage.ObjectInfo{}, false, fmt.Errorf("open existing immutable object %q: %w", key, err)
+	}
+	hash := sha256.New()
+	size, copyErr := io.Copy(hash, file)
+	closeErr := file.Close()
+	if copyErr != nil {
+		return storage.ObjectInfo{}, false, fmt.Errorf("checksum existing immutable object %q: %w", key, copyErr)
+	}
+	if closeErr != nil {
+		return storage.ObjectInfo{}, false, fmt.Errorf("close existing immutable object %q: %w", key, closeErr)
+	}
+	if size != wantSize || hex.EncodeToString(hash.Sum(nil)) != wantSHA256 {
+		return storage.ObjectInfo{}, false, fmt.Errorf("immutable object %q already exists with different content", key)
+	}
+	info, err := verifyPublishedObject(ctx, store, key, wantSize, "")
+	if err != nil {
+		return storage.ObjectInfo{}, false, err
+	}
+	return info, true, nil
+}
+
+func preparePublishTransfer(transfer *publishTransfer) error {
+	if _, err := transfer.Source.Seek(0, io.SeekStart); err != nil {
+		return fmt.Errorf("rewind source %q: %w", transfer.Artifact.Source, err)
+	}
+	info, err := transfer.Source.Stat()
+	if err != nil {
+		return fmt.Errorf("stat source %q: %w", transfer.Artifact.Source, err)
+	}
+	if !info.Mode().IsRegular() {
+		return fmt.Errorf("source %q is not a regular file", transfer.Artifact.Source)
+	}
+	hash := sha256.New()
+	if _, err := io.Copy(hash, transfer.Source); err != nil {
+		return fmt.Errorf("checksum source %q: %w", transfer.Artifact.Source, err)
+	}
+	if _, err := transfer.Source.Seek(0, io.SeekStart); err != nil {
+		return fmt.Errorf("rewind source %q after checksum: %w", transfer.Artifact.Source, err)
+	}
+	transfer.Artifact.Size = info.Size()
+	transfer.Artifact.SHA256 = hex.EncodeToString(hash.Sum(nil))
+	return nil
+}
+
+func verifyPublishedObject(ctx context.Context, store storage.ObjectStore, key string, wantSize int64, uploadedGeneration string) (storage.ObjectInfo, error) {
+	objects, err := store.List(ctx, key)
+	if err != nil {
+		return storage.ObjectInfo{}, fmt.Errorf("list uploaded object %q: %w", key, err)
+	}
+	var found *storage.ObjectInfo
+	for _, object := range objects {
+		if object.Key != key {
+			continue
+		}
+		if found != nil {
+			return storage.ObjectInfo{}, fmt.Errorf("uploaded object %q is ambiguous", key)
+		}
+		copy := object
+		found = &copy
+	}
+	if found == nil {
+		return storage.ObjectInfo{}, fmt.Errorf("uploaded object %q is missing", key)
+	}
+	if found.Size != wantSize {
+		return storage.ObjectInfo{}, fmt.Errorf("uploaded object %q size is %d, want %d", key, found.Size, wantSize)
+	}
+	if strings.TrimSpace(found.ETag) == "" {
+		return storage.ObjectInfo{}, fmt.Errorf("uploaded object %q has no generation", key)
+	}
+	if strings.TrimSpace(uploadedGeneration) != "" && found.ETag != uploadedGeneration {
+		return storage.ObjectInfo{}, fmt.Errorf("uploaded object %q generation changed during verification", key)
+	}
+	return *found, nil
+}
+
+func closePublishTransfers(transfers []publishTransfer) {
+	for _, transfer := range transfers {
+		if transfer.Source != nil {
+			_ = transfer.Source.Close()
+		}
+		if transfer.TemporaryPath != "" {
+			_ = os.Remove(transfer.TemporaryPath)
+		}
+	}
+}
+
+func publishUploadPaths(files []publishUploadFile) []string {
+	paths := make([]string, 0, len(files))
+	for _, file := range files {
+		paths = append(paths, file.RelativePath)
+	}
+	return paths
+}
+
+func publishOutputPaths(outputs []publishOutput) []string {
+	paths := make([]string, 0, len(outputs))
+	for _, output := range outputs {
+		paths = append(paths, output.Dest)
+	}
+	return paths
+}
+
+func publishSHA256(data []byte) string {
+	sum := sha256.Sum256(data)
+	return hex.EncodeToString(sum[:])
+}
+
 func publishDisabled(env *Env) bool {
 	cfg := env.Config.Pipeline.Publish
 	if cfg == nil {
@@ -318,7 +619,7 @@ func validatePublishPrerequisites(m *manifest.Manifest) error {
 	return nil
 }

-func resolvePublishRunRoot(env *Env, m *manifest.Manifest) (string, error) {
+func resolvePublishRunManifestPath(env *Env, m *manifest.Manifest) (string, error) {
 	sessionID := strings.TrimSpace(env.Config.Session.SessionID)
 	if sessionID == "" && m != nil {
 		sessionID = strings.TrimSpace(m.SessionID)
@@ -338,13 +639,13 @@ func resolvePublishRunRoot(env *Env, m *manifest.Manifest) (string, error) {
 		return "", fmt.Errorf("run id is required")
 	}

-	canonical := filepath.Clean(artifacts.SessionRunRootForCampaign(env.Config.Pipeline.Workspace.Root, campaign, sessionID, runID))
-	canonicalExists, err := directoryExists(canonical)
+	canonical := filepath.Clean(artifacts.SessionRunManifestPathForCampaign(env.Config.Pipeline.Workspace.Root, campaign, sessionID, runID))
+	canonicalExists, err := directoryExists(filepath.Dir(canonical))
 	if err != nil {
-		return "", fmt.Errorf("check canonical run root %q: %w", canonical, err)
+		return "", fmt.Errorf("check canonical run manifest directory %q: %w", filepath.Dir(canonical), err)
 	}
 	if !canonicalExists {
-		return "", fmt.Errorf("run root not found for campaign %q session %q run %q at canonical path %q", campaign, sessionID, runID, canonical)
+		return "", fmt.Errorf("run manifest directory not found for campaign %q session %q run %q at canonical path %q", campaign, sessionID, runID, filepath.Dir(canonical))
 	}
 	return canonical, nil
 }
@@ -387,7 +688,7 @@ func resolvePublishOutputs(
 	rules []config.PublishOutputRule,
 	locks []config.PublishLockRule,
 	selectedArtifactKeys []string,
-	sessionPrefix string,
+	runPrefix string,
 ) ([]publishOutput, []string, []publishSkippedUnselectedOutput, []publishLockedOutput, error) {
 	out := make([]publishOutput, 0, len(rules))
 	skippedOptionalOutputs := make([]string, 0)
@@ -423,7 +724,7 @@ func resolvePublishOutputs(
 				lockedOutputs = append(lockedOutputs, publishLockedOutput{
 					Source:    source,
 					Dest:      dest,
-					RemoteKey: artifacts.S3PublishedOutputKey(sessionPrefix, dest),
+					RemoteKey: publishOutputRemoteKey(runPrefix, dest),
 					Reason:    strings.TrimSpace(lock.Reason),
 					Required:  required,
 				})
@@ -442,7 +743,7 @@ func resolvePublishOutputs(
 			lockedOutputs = append(lockedOutputs, publishLockedOutput{
 				Source:     source,
 				Dest:       dest,
-				RemoteKey:  artifacts.S3PublishedOutputKey(sessionPrefix, dest),
+				RemoteKey:  publishOutputRemoteKey(runPrefix, dest),
 				Reason:     strings.TrimSpace(lock.Reason),
 				Required:   required,
 				LocalPath:  resolved.Path,
@@ -810,7 +1111,7 @@ func directoryExists(path string) (bool, error) {
 	return false, err
 }

-func writeCurrentManifestSnapshot(m *manifest.Manifest, publishMetadata map[string]any) (string, error) {
+func writeCommittedSessionManifest(m *manifest.Manifest, publishMetadata map[string]any) (string, error) {
 	if m == nil {
 		return "", fmt.Errorf("manifest is required")
 	}
@@ -840,8 +1141,7 @@ func writeCurrentManifestSnapshot(m *manifest.Manifest, publishMetadata map[stri
 		clone.Stages[name] = &stageCopy
 	}

-	now := time.Now().UTC()
-	clone.MarkStageSucceeded("publish", now, nil)
+	clone.MarkStageSucceeded("publish", clone.UpdatedAt, nil)
 	if sr := clone.Stages["publish"]; sr != nil {
 		sr.Metadata = publishMetadata
 	}
@@ -852,7 +1152,7 @@ func writeCurrentManifestSnapshot(m *manifest.Manifest, publishMetadata map[stri
 	}
 	data = append(data, '\n')

-	tmp, err := os.CreateTemp("", "narratio-current-manifest-*.json")
+	tmp, err := os.CreateTemp("", "narratio-committed-session-manifest-*.json")
 	if err != nil {
 		return "", fmt.Errorf("create temp file: %w", err)
 	}
@@ -867,31 +1167,16 @@ func writeCurrentManifestSnapshot(m *manifest.Manifest, publishMetadata map[stri
 	return path, nil
 }

-func writeCurrentRunIDPointer(runID string) (string, error) {
-	tmp, err := os.CreateTemp("", "narratio-current-run-id-*.txt")
-	if err != nil {
-		return "", fmt.Errorf("create temp file: %w", err)
-	}
-	path := tmp.Name()
-	if _, err := tmp.WriteString(runID + "\n"); err != nil {
-		_ = tmp.Close()
-		return "", fmt.Errorf("write temp run id pointer: %w", err)
-	}
-	if err := tmp.Close(); err != nil {
-		return "", fmt.Errorf("close temp run id pointer: %w", err)
-	}
-	return path, nil
-}
-
-func publishMetadataPreview(
-	bucket, runPrefix, sessionPrefix string,
+func publishMetadata(
+	bucket, runPrefix string,
 	runUploaded []string,
 	publishedUploaded []string,
 	previousUploaded []string,
 	skippedOptionalOutputs []string,
 	skippedUnselectedOutputs []publishSkippedUnselectedOutput,
 	lockedOutputs []publishLockedOutput,
-	currentManifestKey string,
+	commitKey string,
+	pointerKey string,
 ) map[string]any {
 	return map[string]any{
 		"stage":                      "publish",
@@ -908,9 +1193,8 @@ func publishMetadataPreview(
 		"skipped_unselected_outputs": skippedUnselectedOutputMetadata(skippedUnselectedOutputs),
 		"locked_output_count":        len(lockedOutputs),
 		"locked_outputs":             lockedOutputMetadata(lockedOutputs),
-		"current_manifest_key":       currentManifestKey,
-		"current_run_id_key":         artifacts.S3CurrentRunPointerKey(sessionPrefix),
-		"current_pointer_written":    false,
+		"remote_commit_key":          commitKey,
+		"current_commit_pointer_key": pointerKey,
 		"audio_upload_skipped":       true,
 	}
 }
--- a/internal/stage/publish_test.go
+++ b/internal/stage/publish_test.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
-	"io"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -127,8 +126,8 @@ func TestPublishUploadsRunRecordPublishedOutputsAndCurrentPointer(t *testing.T)
 		}
 	}

-	trimmedKey := sessionPrefix + "transcripts/final.trimmed.json"
-	recapKey := sessionPrefix + "artifacts/session_recap.md"
+	trimmedKey := publishOutputRemoteKey(runPrefix, "transcripts/final.trimmed.json")
+	recapKey := publishOutputRemoteKey(runPrefix, "artifacts/session_recap.md")
 	if _, ok := fake.Objects[trimmedKey]; !ok {
 		t.Fatalf("missing published output key %q", trimmedKey)
 	}
@@ -136,16 +135,20 @@ func TestPublishUploadsRunRecordPublishedOutputsAndCurrentPointer(t *testing.T)
 		t.Fatalf("missing published output key %q", recapKey)
 	}

-	currentManifestKey := sessionPrefix + "current/manifest.json"
-	currentRunIDKey := sessionPrefix + "current/run_id.txt"
-	if _, ok := fake.Objects[currentManifestKey]; !ok {
-		t.Fatalf("missing current manifest key %q", currentManifestKey)
+	commitKey := artifacts.S3RunCommitKey(sessionPrefix, m.RunID)
+	pointerKey := artifacts.S3CurrentCommitPointerKey(sessionPrefix)
+	if _, ok := fake.Objects[commitKey]; !ok {
+		t.Fatalf("missing immutable commit key %q", commitKey)
 	}
-	if _, ok := fake.Objects[currentRunIDKey]; !ok {
-		t.Fatalf("missing current run pointer key %q", currentRunIDKey)
+	if _, ok := fake.Objects[pointerKey]; !ok {
+		t.Fatalf("missing current commit pointer key %q", pointerKey)
 	}
-	if got := string(fake.Objects[currentRunIDKey].Data); got != m.RunID+"\n" {
-		t.Fatalf("run pointer contents = %q, want %q", got, m.RunID+"\\n")
+	pointer, err := artifacts.DecodeCurrentCommitPointer(fake.Objects[pointerKey].Data)
+	if err != nil {
+		t.Fatalf("DecodeCurrentCommitPointer() error = %v", err)
+	}
+	if pointer.CommitKey != commitKey || pointer.RunID != m.RunID {
+		t.Fatalf("pointer = %#v, want selected commit %q", pointer, commitKey)
 	}

 	audioKey := runPrefix + "audio/speaker.flac"
@@ -157,12 +160,12 @@ func TestPublishUploadsRunRecordPublishedOutputsAndCurrentPointer(t *testing.T)
 	if len(uploads) == 0 {
 		t.Fatal("expected uploads")
 	}
-	if uploads[len(uploads)-1].Key != currentRunIDKey {
-		t.Fatalf("last upload key = %q, want current run pointer key %q", uploads[len(uploads)-1].Key, currentRunIDKey)
+	if uploads[len(uploads)-1].Key != pointerKey {
+		t.Fatalf("last upload key = %q, want current commit pointer key %q", uploads[len(uploads)-1].Key, pointerKey)
 	}

-	if result.Metadata["current_pointer_written"] != true {
-		t.Fatalf("metadata = %#v, want current_pointer_written=true", result.Metadata)
+	if result.Metadata["current_commit_pointer_key"] != pointerKey {
+		t.Fatalf("metadata = %#v, want current commit pointer key", result.Metadata)
 	}
 	if result.Metadata["published_files_uploaded"] != 2 {
 		t.Fatalf("metadata published_files_uploaded = %#v, want 2", result.Metadata["published_files_uploaded"])
@@ -195,8 +198,8 @@ func TestPublishUploadsPreviousCacheWhenPresent(t *testing.T) {
 		t.Fatalf("Run() error = %v", err)
 	}

-	previousManifestKey := m.S3SessionPrefix + "previous/manifest.json"
-	previousRecapKey := m.S3SessionPrefix + "previous/artifacts/session_recap.md"
+	previousManifestKey := artifacts.S3RunRelativeDestinationKey(m.S3RunPrefix, "previous/manifest.json")
+	previousRecapKey := artifacts.S3RunRelativeDestinationKey(m.S3RunPrefix, "previous/artifacts/session_recap.md")
 	if _, ok := fake.Objects[previousManifestKey]; !ok {
 		t.Fatalf("missing published previous manifest key %q", previousManifestKey)
 	}
@@ -405,10 +408,10 @@ func TestPublishUsesCustomOutputRules(t *testing.T) {
 	}

 	fake := env.ObjectStore.(*storage.FakeBackend)
-	if _, ok := fake.Objects[m.S3SessionPrefix+"published/trimmed.json"]; !ok {
+	if _, ok := fake.Objects[publishOutputRemoteKey(m.S3RunPrefix, "published/trimmed.json")]; !ok {
 		t.Fatalf("missing custom published trimmed key")
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"published/recap.md"]; !ok {
+	if _, ok := fake.Objects[publishOutputRemoteKey(m.S3RunPrefix, "published/recap.md")]; !ok {
 		t.Fatalf("missing custom published recap key")
 	}
 }
@@ -427,7 +430,7 @@ func TestPublishUploadsExplicitExtractionAndPreservesManifestMetadata(t *testing
 	}
 	fake := env.ObjectStore.(*storage.FakeBackend)
 	durableBundleRoot := filepath.Dir(filepath.Dir(lanePath))
-	publishedKey := m.S3SessionPrefix + "artifacts/encounters.json"
+	publishedKey := publishOutputRemoteKey(m.S3RunPrefix, "artifacts/encounters.json")
 	if got := string(fake.Objects[publishedKey].Data); got != `{"encounters":[]}` {
 		t.Fatalf("published extraction = %q", got)
 	}
@@ -448,13 +451,13 @@ func TestPublishUploadsExplicitExtractionAndPreservesManifestMetadata(t *testing
 	if result.Metadata["published_files_uploaded"] != 1 {
 		t.Fatalf("published_files_uploaded = %#v, want 1", result.Metadata["published_files_uploaded"])
 	}
-	if uploads := fake.Uploads; len(uploads) == 0 || uploads[len(uploads)-1].Key != m.S3SessionPrefix+"current/run_id.txt" {
+	if uploads := fake.Uploads; len(uploads) == 0 || uploads[len(uploads)-1].Key != artifacts.S3CurrentCommitPointerKey(m.S3SessionPrefix) {
 		t.Fatalf("last upload = %#v, want current run pointer", uploads)
 	}

 	var current manifest.Manifest
-	if err := json.Unmarshal(fake.Objects[m.S3SessionPrefix+"current/manifest.json"].Data, &current); err != nil {
-		t.Fatalf("unmarshal current manifest: %v", err)
+	if err := json.Unmarshal(fake.Objects[artifacts.S3RunSessionManifestKey(m.S3SessionPrefix, m.RunID)].Data, &current); err != nil {
+		t.Fatalf("unmarshal committed session manifest: %v", err)
 	}
 	extractRecord := current.Stages["extract"]
 	if extractRecord == nil || len(extractRecord.Outputs) != 2 {
@@ -528,7 +531,7 @@ func TestPublishArtifactSelectionDoesNotFilterExtractionOutputs(t *testing.T) {
 	if _, err := (publishStage{}).Run(context.Background(), env, m); err != nil {
 		t.Fatalf("Run() error = %v", err)
 	}
-	if _, ok := env.ObjectStore.(*storage.FakeBackend).Objects[m.S3SessionPrefix+"artifacts/encounters.json"]; !ok {
+	if _, ok := env.ObjectStore.(*storage.FakeBackend).Objects[publishOutputRemoteKey(m.S3RunPrefix, "artifacts/encounters.json")]; !ok {
 		t.Fatal("explicit extraction output was filtered by Scriptorium artifact selection")
 	}
 }
@@ -565,10 +568,10 @@ func TestPublishSkipsRequiredUnselectedConfiguredOutput(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Run() error = %v", err)
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"transcripts/final.trimmed.json"]; !ok {
+	if _, ok := fake.Objects[publishOutputRemoteKey(m.S3RunPrefix, "transcripts/final.trimmed.json")]; !ok {
 		t.Fatalf("missing built-in published trimmed key")
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"artifacts/session_recap.md"]; ok {
+	if _, ok := fake.Objects[publishOutputRemoteKey(m.S3RunPrefix, "artifacts/session_recap.md")]; ok {
 		t.Fatalf("unexpected unselected recap published output upload")
 	}
 	skipped := result.Metadata["skipped_unselected_outputs"].([]map[string]any)
@@ -581,7 +584,7 @@ func TestPublishSkipsRequiredUnselectedConfiguredOutput(t *testing.T) {
 	if result.Metadata["locked_output_count"] != 0 {
 		t.Fatalf("locked_output_count = %#v, want 0", result.Metadata["locked_output_count"])
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"current/run_id.txt"]; !ok {
+	if _, ok := fake.Objects[artifacts.S3CurrentCommitPointerKey(m.S3SessionPrefix)]; !ok {
 		t.Fatalf("missing current pointer")
 	}
 }
@@ -616,7 +619,7 @@ func TestPublishLockedSelectedOutputSkipsAsLocked(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Run() error = %v", err)
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"artifacts/session_recap.md"]; ok {
+	if _, ok := fake.Objects[publishOutputRemoteKey(m.S3RunPrefix, "artifacts/session_recap.md")]; ok {
 		t.Fatalf("unexpected locked recap published output upload")
 	}
 	if result.Metadata["locked_output_count"] != 1 {
@@ -665,11 +668,11 @@ func TestPublishSkipsLockedRequiredOutputAndCommits(t *testing.T) {
 		t.Fatalf("Run() error = %v", err)
 	}

-	trimmedKey := m.S3SessionPrefix + "transcripts/final.trimmed.json"
+	trimmedKey := publishOutputRemoteKey(m.S3RunPrefix, "transcripts/final.trimmed.json")
 	if _, ok := fake.Objects[trimmedKey]; ok {
 		t.Fatalf("locked published output key %q should not be uploaded", trimmedKey)
 	}
-	recapKey := m.S3SessionPrefix + "artifacts/session_recap.md"
+	recapKey := publishOutputRemoteKey(m.S3RunPrefix, "artifacts/session_recap.md")
 	if _, ok := fake.Objects[recapKey]; !ok {
 		t.Fatalf("unlocked published output key %q should be uploaded", recapKey)
 	}
@@ -678,9 +681,9 @@ func TestPublishSkipsLockedRequiredOutputAndCommits(t *testing.T) {
 		t.Fatalf("run-local locked source output %q should still be uploaded", runTrimmedKey)
 	}

-	currentRunIDKey := m.S3SessionPrefix + "current/run_id.txt"
-	if len(fake.Uploads) == 0 || fake.Uploads[len(fake.Uploads)-1].Key != currentRunIDKey {
-		t.Fatalf("last upload = %#v, want current run pointer %q", fake.Uploads, currentRunIDKey)
+	pointerKey := artifacts.S3CurrentCommitPointerKey(m.S3SessionPrefix)
+	if len(fake.Uploads) == 0 || fake.Uploads[len(fake.Uploads)-1].Key != pointerKey {
+		t.Fatalf("last upload = %#v, want current commit pointer %q", fake.Uploads, pointerKey)
 	}

 	if result.Metadata["published_files_uploaded"] != 1 {
@@ -703,7 +706,7 @@ func TestPublishSkipsLockedRequiredOutputAndCommits(t *testing.T) {
 		t.Fatalf("locked published output metadata = %#v", locked[0])
 	}

-	currentManifestKey := m.S3SessionPrefix + "current/manifest.json"
+	currentManifestKey := artifacts.S3RunSessionManifestKey(m.S3SessionPrefix, m.RunID)
 	var current map[string]any
 	if err := json.Unmarshal(fake.Objects[currentManifestKey].Data, &current); err != nil {
 		t.Fatalf("unmarshal current manifest: %v", err)
@@ -735,12 +738,12 @@ func TestPublishLockedRequiredMissingOutputSucceeds(t *testing.T) {
 	}

 	fake := env.ObjectStore.(*storage.FakeBackend)
-	mergedKey := m.S3SessionPrefix + "transcripts/base.json"
+	mergedKey := publishOutputRemoteKey(m.S3RunPrefix, "transcripts/base.json")
 	if _, ok := fake.Objects[mergedKey]; ok {
 		t.Fatalf("locked missing published output key %q should not be uploaded", mergedKey)
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"current/run_id.txt"]; !ok {
-		t.Fatalf("current run pointer should be written for locked missing output")
+	if _, ok := fake.Objects[artifacts.S3CurrentCommitPointerKey(m.S3SessionPrefix)]; !ok {
+		t.Fatalf("current commit pointer should be written for locked missing output")
 	}
 	locked := result.Metadata["locked_outputs"].([]map[string]any)
 	if len(locked) != 1 {
@@ -757,7 +760,7 @@ func TestPublishLockDoesNotOverwriteExistingOutput(t *testing.T) {
 		{Source: "narratio.transcript.final_trimmed", Reason: "already published"},
 	}
 	fake := env.ObjectStore.(*storage.FakeBackend)
-	trimmedKey := m.S3SessionPrefix + "transcripts/final.trimmed.json"
+	trimmedKey := publishOutputRemoteKey(m.S3RunPrefix, "transcripts/final.trimmed.json")
 	fake.SeedObject(storage.FakeObject{Key: trimmedKey, Data: []byte("previously published\n")})

 	if _, err := (publishStage{}).Run(context.Background(), env, m); err != nil {
@@ -797,49 +800,145 @@ func TestPublishFailsWhenCanonicalRunRootMissing(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected missing run-root error, got nil")
 	}
-	if !strings.Contains(err.Error(), "run root not found") {
-		t.Fatalf("error = %v, want missing run-root error", err)
+	if !strings.Contains(err.Error(), "run manifest directory not found") {
+		t.Fatalf("error = %v, want missing run-manifest directory error", err)
 	}
 }

-func TestPublishDoesNotWriteCurrentPointerWhenOutputUploadFails(t *testing.T) {
+func TestPublishFailurePreservesPreviousCommittedSnapshotAndRetryIsDeterministic(t *testing.T) {
 	env, m, _ := publishFixture(t)
 	fake := env.ObjectStore.(*storage.FakeBackend)
-	trimmedKey := m.S3SessionPrefix + "transcripts/final.trimmed.json"
+	oldRunID := "20260515T010203Z-a1b2c3d4"
+	seedCommittedCurrentState(t, fake, m, oldRunID)
+	pointerKey := artifacts.S3CurrentCommitPointerKey(m.S3SessionPrefix)
+	priorPointer := append([]byte(nil), fake.Objects[pointerKey].Data...)
+	failingKey := publishOutputRemoteKey(m.S3RunPrefix, "transcripts/final.trimmed.json")
+	fake.UploadHook = func(call storage.FakeUploadCall) error {
+		if call.Key == failingKey {
+			return errors.New("forced upload failure")
+		}
+		return nil
+	}

-	origUploadErr := fake.UploadErr
-	fake.UploadErr = nil
-	failingKey := trimmedKey
+	_, err := publishStage{}.Run(context.Background(), env, m)
+	if err == nil || !strings.Contains(err.Error(), "forced upload failure") {
+		t.Fatalf("Run() error = %v, want immutable object upload failure", err)
+	}
+	if got := fake.Objects[pointerKey].Data; !reflect.DeepEqual(got, priorPointer) {
+		t.Fatalf("current pointer changed after failed publication: %q", got)
+	}
+	state, err := artifacts.LoadCurrentState(context.Background(), fake, m.S3SessionPrefix, artifacts.CurrentStateValidation{ValidateRunID: true})
+	if err != nil {
+		t.Fatalf("LoadCurrentState() error = %v", err)
+	}
+	if state.RunID != oldRunID {
+		t.Fatalf("readable current run = %q, want %q", state.RunID, oldRunID)
+	}
+	for _, upload := range fake.Uploads {
+		if upload.Key == pointerKey {
+			t.Fatalf("current pointer was uploaded after a pre-commit failure")
+		}
+	}
+
+	fake.UploadHook = nil
 	fake.Uploads = nil
-
-	originalUpload := fake.Upload
-	_ = originalUpload
-	// Use UploadErr toggle by checking call sequence in postcondition.
-	// First failure point is published output upload; simulate by setting error immediately before published output key write.
-	// We cannot hook FakeBackend per-key without changing public behavior; use dedicated backend wrapper instead.
-	env.ObjectStore = &publishedOutputFailingStore{delegate: fake, failKey: failingKey}
-
-	_, err := publishStage{}.Run(context.Background(), env, m)
-	if err == nil || !strings.Contains(err.Error(), "upload published output source") {
-		t.Fatalf("Run() error = %v, want published output upload failure", err)
+	if _, err := (publishStage{}).Run(context.Background(), env, m); err != nil {
+		t.Fatalf("retry Run() error = %v", err)
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"current/run_id.txt"]; ok {
-		t.Fatalf("unexpected current pointer write on published output failure")
+	if len(fake.Uploads) == 0 || fake.Uploads[len(fake.Uploads)-1].Key != pointerKey {
+		t.Fatalf("retry uploads = %#v, want pointer as final mutation", fake.Uploads)
+	}
+	state, err = artifacts.LoadCurrentState(context.Background(), fake, m.S3SessionPrefix, artifacts.CurrentStateValidation{ValidateRunID: true})
+	if err != nil {
+		t.Fatalf("LoadCurrentState() after retry error = %v", err)
+	}
+	if state.RunID != m.RunID {
+		t.Fatalf("retried current run = %q, want %q", state.RunID, m.RunID)
+	}
+	if state.Commit == nil {
+		t.Fatal("retried current state has no immutable commit")
+	}
+	destinations := make([]string, 0, len(state.Commit.Artifacts))
+	for _, artifact := range state.Commit.Artifacts {
+		destinations = append(destinations, artifact.DestinationKey)
+	}
+	if !sort.StringsAreSorted(destinations) {
+		t.Fatalf("retried immutable mapping is not deterministic: %v", destinations)
+	}
+	if _, exists := fake.Objects[m.S3SessionPrefix+"current/manifest.json"]; exists {
+		t.Fatal("new publication wrote legacy current manifest")
 	}
-	fake.UploadErr = origUploadErr
 }

-func TestPublishDoesNotWriteCurrentPointerWhenCurrentManifestUploadFails(t *testing.T) {
+func TestPublishRejectsConflictingImmutableObject(t *testing.T) {
 	env, m, _ := publishFixture(t)
 	fake := env.ObjectStore.(*storage.FakeBackend)
-	env.ObjectStore = &publishedOutputFailingStore{delegate: fake, failKey: m.S3SessionPrefix + "current/manifest.json"}
+	conflictingKey := publishOutputRemoteKey(m.S3RunPrefix, "transcripts/final.trimmed.json")
+	fake.SeedObject(storage.FakeObject{Key: conflictingKey, Data: []byte("different content\n")})

-	_, err := publishStage{}.Run(context.Background(), env, m)
-	if err == nil || !strings.Contains(err.Error(), "current manifest") {
-		t.Fatalf("Run() error = %v, want current manifest upload failure", err)
+	_, err := (publishStage{}).Run(context.Background(), env, m)
+	if err == nil || !strings.Contains(err.Error(), "already exists with different content") {
+		t.Fatalf("Run() error = %v, want immutable conflict", err)
 	}
-	if _, ok := fake.Objects[m.S3SessionPrefix+"current/run_id.txt"]; ok {
-		t.Fatalf("unexpected current pointer write when current manifest upload fails")
+	if _, exists := fake.Objects[artifacts.S3CurrentCommitPointerKey(m.S3SessionPrefix)]; exists {
+		t.Fatal("current pointer was updated after immutable object conflict")
+	}
+}
+
+func TestPublishRejectsAmbiguousOrCollidingOutputMappings(t *testing.T) {
+	tests := []struct {
+		name    string
+		outputs []config.PublishOutputRule
+	}{
+		{
+			name: "ambiguous source",
+			outputs: []config.PublishOutputRule{
+				{Source: "narratio.transcript.final_trimmed", Dest: "published/first.json", Required: boolPtr(true)},
+				{Source: "narratio.transcript.final_trimmed", Dest: "published/second.json", Required: boolPtr(true)},
+			},
+		},
+		{
+			name: "colliding destination",
+			outputs: []config.PublishOutputRule{
+				{Source: "narratio.transcript.final_trimmed", Dest: "published/shared.json", Required: boolPtr(true)},
+				{Source: "narratio.artifact.session_recap", Dest: "published/shared.json", Required: boolPtr(true)},
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			env, m, _ := publishFixture(t)
+			env.Config.Pipeline.Publish.Outputs = test.outputs
+			_, err := (publishStage{}).Run(context.Background(), env, m)
+			if err == nil || !strings.Contains(err.Error(), "immutable upload mapping") {
+				t.Fatalf("Run() error = %v, want invalid mapping", err)
+			}
+			if uploads := env.ObjectStore.(*storage.FakeBackend).Uploads; len(uploads) != 0 {
+				t.Fatalf("uploads = %#v, want mapping failure before upload", uploads)
+			}
+		})
+	}
+}
+
+func TestPublishKeepsSameBasenameSourcesDistinct(t *testing.T) {
+	env, m, _ := publishFixture(t)
+	writeStageTestFile(t, filepath.Join(env.Config.Pipeline.Workspace.Root, "work", m.Campaign, m.SessionID, "reports", "session_recap.md"), "# other recap\n")
+	env.Config.Pipeline.Scriptorium.Artifacts["other_recap"] = config.ScriptoriumArtifactConfig{
+		Enabled: true, PromptID: "dnd.other_recap", OutputPath: "reports/session_recap.md",
+	}
+	env.Config.Pipeline.Publish.Outputs = []config.PublishOutputRule{
+		{Source: "narratio.artifact.session_recap", Dest: "published/first/session_recap.md", Required: boolPtr(true)},
+		{Source: "narratio.artifact.other_recap", Dest: "published/second/session_recap.md", Required: boolPtr(true)},
+	}
+
+	if _, err := (publishStage{}).Run(context.Background(), env, m); err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+	fake := env.ObjectStore.(*storage.FakeBackend)
+	first := publishOutputRemoteKey(m.S3RunPrefix, "published/first/session_recap.md")
+	second := publishOutputRemoteKey(m.S3RunPrefix, "published/second/session_recap.md")
+	if string(fake.Objects[first].Data) != "# recap\n" || string(fake.Objects[second].Data) != "# other recap\n" {
+		t.Fatalf("same-basename outputs were not kept distinct: first=%q second=%q", fake.Objects[first].Data, fake.Objects[second].Data)
 	}
 }

@@ -1022,35 +1121,53 @@ func configurePublishExtractionFixture(t *testing.T, env *Env, m *manifest.Manif
 	return lanePath
 }

-type publishedOutputFailingStore struct {
-	delegate *storage.FakeBackend
-	failKey  string
-}
-
-func (s *publishedOutputFailingStore) List(ctx context.Context, prefix string) ([]storage.ObjectInfo, error) {
-	return s.delegate.List(ctx, prefix)
-}
-
-func (s *publishedOutputFailingStore) Download(ctx context.Context, key, localPath string) error {
-	return s.delegate.Download(ctx, key, localPath)
-}
-
-func (s *publishedOutputFailingStore) Upload(ctx context.Context, localPath, key string, opts storage.UploadOptions) (storage.ObjectInfo, error) {
-	if strings.TrimSpace(key) == strings.TrimSpace(s.failKey) {
-		return storage.ObjectInfo{}, errors.New("forced upload failure")
+func seedCommittedCurrentState(t *testing.T, fake *storage.FakeBackend, source *manifest.Manifest, runID string) {
+	t.Helper()
+	copy := *source
+	copy.RunID = runID
+	manifestData, err := json.Marshal(&copy)
+	if err != nil {
+		t.Fatalf("marshal committed manifest: %v", err)
 	}
-	return s.delegate.Upload(ctx, localPath, key, opts)
-}
-
-func (s *publishedOutputFailingStore) UploadReader(ctx context.Context, source io.Reader, key string, opts storage.UploadOptions) (storage.ObjectInfo, error) {
-	if strings.TrimSpace(key) == strings.TrimSpace(s.failKey) {
-		return storage.ObjectInfo{}, errors.New("forced upload failure")
+	manifestData = append(manifestData, '\n')
+	manifestKey := artifacts.S3RunSessionManifestKey(copy.S3SessionPrefix, runID)
+	fake.SeedObject(storage.FakeObject{Key: manifestKey, Data: manifestData})
+	manifestObject := fake.Objects[manifestKey]
+	commit := artifacts.RemoteCommitManifest{
+		FormatVersion: artifacts.RemoteCommitFormatVersion,
+		Campaign:      copy.Campaign,
+		SessionID:     copy.SessionID,
+		RunID:         runID,
+		Artifacts: []artifacts.RemoteArtifact{{
+			Type:           artifacts.RemoteArtifactTypeSessionManifest,
+			Source:         "session.manifest",
+			DestinationKey: manifestKey,
+			SHA256:         publishSHA256(manifestData),
+			Size:           int64(len(manifestData)),
+			Generation:     manifestObject.ETag,
+		}},
 	}
-	return s.delegate.UploadReader(ctx, source, key, opts)
-}
-
-func (s *publishedOutputFailingStore) Exists(ctx context.Context, key string) (bool, error) {
-	return s.delegate.Exists(ctx, key)
+	commitData, err := artifacts.EncodeRemoteCommitManifest(commit)
+	if err != nil {
+		t.Fatalf("encode remote commit: %v", err)
+	}
+	commitKey := artifacts.S3RunCommitKey(copy.S3SessionPrefix, runID)
+	fake.SeedObject(storage.FakeObject{Key: commitKey, Data: commitData})
+	commitObject := fake.Objects[commitKey]
+	pointerData, err := artifacts.EncodeCurrentCommitPointer(artifacts.CurrentCommitPointer{
+		FormatVersion:    artifacts.RemoteCommitFormatVersion,
+		Campaign:         copy.Campaign,
+		SessionID:        copy.SessionID,
+		RunID:            runID,
+		CommitKey:        commitKey,
+		CommitSHA256:     publishSHA256(commitData),
+		CommitSize:       int64(len(commitData)),
+		CommitGeneration: commitObject.ETag,
+	})
+	if err != nil {
+		t.Fatalf("encode current commit pointer: %v", err)
+	}
+	fake.SeedObject(storage.FakeObject{Key: artifacts.S3CurrentCommitPointerKey(copy.S3SessionPrefix), Data: pointerData})
 }

 func boolPtr(v bool) *bool {