feat: add runtime per session

docs/qa/scenarios/RT-010.md

@@ -4,7 +4,7 @@ area: RT
 title: Create session
 persona: Bruno
 journey: J-17
-expected: `POST /api/sessions` with `{workspace|workspace_path, agent_name, provider?, model?, reasoning_effort?, name?, network_participation?}` validates the target, returns a durable `starting` session with an immutable Local/Live snapshot, then becomes `active` or durably `stopped` with startup diagnostics; invalid admission requests fail without a catalog row.
+expected: `POST /api/sessions` with `{workspace|workspace_path, agent_name, prompt?, provider?, model?, reasoning_effort?, name?, network_participation?}` validates the target, durably queues a non-empty first prompt before returning the `starting` session with an immutable Local/Live snapshot, then dispatches that prompt exactly once after activation or a later resume; invalid admission and prompt-queue failures leave no session residue.
 entry_points: HTTP+UDS `POST /api/sessions`; web session-create-dialog
 qa_status: untested
 bug_ids: BUG-0002; BUG-0003
@@ -33,3 +33,5 @@ Task43 QA 2026-07-08: scenario covered by persona charter plus required E2E lane
 Model-selector QA 2026-07-10: charter walked; live/manual, structured-surface, and official E2E evidence passed.
 
 QA impact 2026-07-22: public creation now accepts durably before ACP startup and reports background startup failures on the session record. Runtime fields may all be omitted to inherit project defaults. Reset to untested.
+
+QA impact 2026-07-25: create may atomically stage the first prompt before the `201`; activation or resume dispatches it exactly once under the selected immutable runtime. Reset to untested; flag only.

docs/qa/scenarios/RT-063.md

@@ -4,7 +4,7 @@ area: RT
 title: Session-create via unified runtime selector
 persona: Bruno
 journey: J-17
-expected: The trigger renders the agent's workspace-scoped effective provider·model·reasoning; submitting untouched omits all runtime fields to preserve project inheritance, while an explicit selector change sends one coherent session override.
+expected: The composer trigger renders the agent's workspace-scoped effective provider·model·reasoning without a button-like border or background; sending an untouched runtime omits all runtime fields to preserve project inheritance, while an explicit selector change atomically creates the session with one coherent runtime override and the required first prompt.
 entry_points: web session-create dialog; POST /api/sessions
 qa_status: untested
 bug_ids: BUG-0024
@@ -21,3 +21,5 @@ story: model-selector task_02 — unified RuntimeSelector replaces the three lea
 Model-selector QA 2026-07-10: charter walked; live/manual, structured-surface, and official E2E evidence passed. BUG-0024 is fixed and retested in the uncommitted worktree; no SHA exists by explicit user direction.
 
 QA impact 2026-07-22: session-create now consumes `effective_runtime` and distinguishes untouched inheritance from explicit overrides. Reset to untested.
+
+QA impact 2026-07-25: RuntimeSelector moved into the first-message composer; Send is the sole creation action and the daemon owns deferred first-prompt dispatch. Reset to untested; flag only.

docs/qa/scenarios/RT-072.md

@@ -4,7 +4,7 @@ area: RT
 title: Claude max reasoning via the web selector
 persona: Bruno
 journey: J-21
-expected: A Claude session created through the web selector with reasoning_effort=max applies the advertised ACP effort after model selection and before the first prompt (browser-use highest-risk flow).
+expected: A Claude session created through the web composer with reasoning_effort=max applies the advertised ACP effort after model selection and before the atomically queued first prompt is dispatched exactly once (browser-use highest-risk flow).
 entry_points: web session-create to Claude to max; browser-use:browser
 qa_status: untested
 bug_ids: BUG-0024
@@ -21,3 +21,5 @@ story: model-selector task_04 highest-risk browser-use flow; execution captures
 Model-selector QA 2026-07-10: charter walked; live/manual, structured-surface, and official E2E evidence passed. BUG-0024 is fixed and retested in the uncommitted worktree; no SHA exists by explicit user direction.
 
 2026-07-22 selector redesign: reasoning is now picked on a slider (no None or Default stops; the model default renders preselected while the wire value stays empty). Max is the last stop. Flagged untested for the next QA cycle.
+
+QA impact 2026-07-25: the composer sends the first prompt and max-reasoning override in one create request; the daemon applies runtime overrides before deferred prompt dispatch. Reset to untested; flag only.

docs/qa/scenarios/RT-new-session-fast-feedback.md

@@ -4,7 +4,7 @@ area: RT
 title: Start a new session with immediate truthful feedback
 persona: Bruno
 journey: J-17
-expected: Clicking New session gives visible feedback within 100 ms, navigates to one durable `starting` session within 250 ms, keeps the composer disabled until `active`, and surfaces a durable startup failure without duplicate creation; runtime-related failures link to runtime settings, while unrelated startup failures do not.
+expected: Clicking New session opens a first-message composer; Send gives visible feedback within 100 ms, atomically queues the prompt, navigates to one durable `starting` session within 250 ms, and surfaces a durable startup failure without duplicate creation; the queued prompt remains available for explicit resume and is never posted a second time by the web client.
 entry_points: web agent detail New session; web Agents Start session
 qa_status: untested
 bug_ids: BUG-20260713-cursor-model-startup-contract, BUG-20260713-new-session-modal-lingers, BUG-20260713-first-prompt-optimistic-stuck, BUG-20260713-stop-generation-local-stuck
@@ -43,3 +43,5 @@ verified.
 QA impact 2026-07-22: session admission is now durable and asynchronous, the Web polls `starting`
 at 500 ms, and startup failure has an explicit recovery pane. Reset to untested for a fresh timing
 and failure-path replay.
+
+QA impact 2026-07-25: first-message creation is now atomic: the `201 starting` session already owns the queued prompt, navigation remains immediate, and resume delivers a prompt retained across startup failure. Reset to untested; flag only.

internal/api/contract/contract_test.go

@@ -612,6 +612,34 @@ func TestCreateSessionRequestJSONShape(t *testing.T) {
 		}
 	})
 
+	t.Run("Should round-trip the optional initial prompt", func(t *testing.T) {
+		t.Parallel()
+
+		req := contract.CreateSessionRequest{
+			AgentName: "coder",
+			Workspace: "alpha",
+			Prompt:    "Investigate the failing build",
+		}
+		raw, err := json.Marshal(req)
+		if err != nil {
+			t.Fatalf("json.Marshal() error = %v", err)
+		}
+		var decoded contract.CreateSessionRequest
+		if err := json.Unmarshal(raw, &decoded); err != nil {
+			t.Fatalf("json.Unmarshal() error = %v", err)
+		}
+		if decoded.Prompt != req.Prompt {
+			t.Fatalf("decoded.Prompt = %q, want %q", decoded.Prompt, req.Prompt)
+		}
+		var shape map[string]any
+		if err := json.Unmarshal(raw, &shape); err != nil {
+			t.Fatalf("json.Unmarshal(map) error = %v", err)
+		}
+		if shape["prompt"] != req.Prompt {
+			t.Fatalf("shape = %#v, want prompt key %q", shape, req.Prompt)
+		}
+	})
+
 	t.Run("Should omit model and reasoning_effort cleanly when absent", func(t *testing.T) {
 		t.Parallel()
 
@@ -624,6 +652,18 @@ func TestCreateSessionRequestJSONShape(t *testing.T) {
 			t.Fatalf("raw = %s", string(raw))
 		}
 	})
+
+	t.Run("Should omit prompt cleanly when absent", func(t *testing.T) {
+		t.Parallel()
+
+		raw, err := json.Marshal(contract.CreateSessionRequest{AgentName: "coder", Workspace: "alpha"})
+		if err != nil {
+			t.Fatalf("json.Marshal() error = %v", err)
+		}
+		if strings.Contains(string(raw), "prompt") {
+			t.Fatalf("raw = %s, want prompt omitted", string(raw))
+		}
+	})
 }
 
 func TestMemoryV2PublicContractJSONShape(t *testing.T) {

internal/api/contract/session_runtime_payloads.go

@@ -20,6 +20,7 @@ type CreateSessionRequest struct {
 	Provider             string                 `json:"provider,omitempty"`
 	Model                string                 `json:"model,omitempty"`
 	ReasoningEffort      ReasoningEffort        `json:"reasoning_effort,omitempty"`
+	Prompt               string                 `json:"prompt,omitempty"`
 	Name                 string                 `json:"name,omitempty"`
 	Workspace            string                 `json:"workspace,omitempty"`
 	WorkspacePath        string                 `json:"workspace_path,omitempty"`

internal/api/core/handlers.go

@@ -80,7 +80,10 @@ func (h *BaseHandlers) CreateSession(c *gin.Context) {
 		)
 		return
 	}
-	info, err := h.SessionAcceptance.CreateAccepted(c.Request.Context(), opts)
+	info, err := h.SessionAcceptance.CreateAccepted(c.Request.Context(), session.CreateAcceptedOpts{
+		Session:       opts,
+		InitialPrompt: strings.TrimSpace(req.Prompt),
+	})
 	if err != nil {
 		h.respondError(c, StatusForSessionError(err), err)
 		return

internal/api/core/handlers_test.go

@@ -46,27 +46,20 @@ func TestBaseHandlersSessionEndpoints(t *testing.T) {
 		ListAllFn: func(context.Context) ([]*session.Info, error) {
 			return []*session.Info{testutil.NewSessionInfo("sess-a")}, nil
 		},
-		CreateFn: func(_ context.Context, opts session.CreateOpts) (*session.Session, error) {
-			createCalled.Store(true)
-			if opts.AgentName != "coder" ||
-				opts.Provider != "fake" ||
-				opts.Workspace != "alpha" ||
-				opts.Type != session.SessionTypeUser {
-				t.Fatalf("Create opts = %#v", opts)
-			}
-			created := testutil.NewSession("sess-created")
-			created.AgentName = opts.AgentName
-			created.Provider = opts.Provider
-			return created, nil
-		},
-		CreateAcceptedFn: func(_ context.Context, opts session.CreateOpts) (*session.Info, error) {
+		CreateAcceptedFn: func(_ context.Context, acceptedOpts session.CreateAcceptedOpts) (*session.Info, error) {
 			createCalled.Store(true)
+			opts := acceptedOpts.Session
 			if opts.AgentName != "coder" ||
 				opts.Provider != "fake" ||
+				opts.Model != "fake-pro" ||
+				opts.ReasoningEffort != "high" ||
 				opts.Workspace != "alpha" ||
 				opts.Type != session.SessionTypeUser {
 				t.Fatalf("CreateAccepted opts = %#v", opts)
 			}
+			if acceptedOpts.InitialPrompt != "Investigate the failing build" {
+				t.Fatalf("CreateAccepted initial prompt = %q", acceptedOpts.InitialPrompt)
+			}
 			created := testutil.NewSessionInfo("sess-created")
 			created.AgentName = opts.AgentName
 			created.Provider = opts.Provider
@@ -190,7 +183,14 @@ func TestBaseHandlersSessionEndpoints(t *testing.T) {
 			fixture.Engine,
 			http.MethodPost,
 			"/sessions",
-			[]byte(`{"agent_name":"coder","provider":"fake","workspace":"alpha"}`),
+			[]byte(`{
+				"agent_name":"coder",
+				"provider":"fake",
+				"model":"fake-pro",
+				"reasoning_effort":"high",
+				"workspace":"alpha",
+				"prompt":"  Investigate the failing build  "
+			}`),
 		)
 		if createResp.Code != http.StatusCreated || !createCalled.Load() {
 			t.Fatalf("create status = %d, called=%v", createResp.Code, createCalled.Load())

internal/api/core/interfaces.go

@@ -99,7 +99,7 @@ type SessionManager interface {
 // SessionAcceptanceManager durably accepts user-created sessions without
 // waiting for provider startup.
 type SessionAcceptanceManager interface {
-	CreateAccepted(ctx context.Context, opts session.CreateOpts) (*session.Info, error)
+	CreateAccepted(ctx context.Context, opts session.CreateAcceptedOpts) (*session.Info, error)
 }
 
 // DaemonDrainController owns daemon-global new-work admission state.

internal/api/testutil/session_stub.go

@@ -2,6 +2,8 @@ package testutil
 
 import (
 	"context"
+	"errors"
+	"strings"
 
 	"github.com/compozy/agh/internal/acp"
 	core "github.com/compozy/agh/internal/api/core"
@@ -13,7 +15,7 @@ import (
 
 type StubSessionManager struct {
 	CreateFn            func(context.Context, session.CreateOpts) (*session.Session, error)
-	CreateAcceptedFn    func(context.Context, session.CreateOpts) (*session.Info, error)
+	CreateAcceptedFn    func(context.Context, session.CreateAcceptedOpts) (*session.Info, error)
 	ListFn              func() []*session.Info
 	ListAllFn           func(context.Context) ([]*session.Info, error)
 	ListPageFn          func(context.Context, session.ListQuery) (session.ListPage, error)
@@ -56,11 +58,17 @@ func (s StubSessionManager) Create(ctx context.Context, opts session.CreateOpts)
 	return nil, session.ErrSessionNotFound
 }
 
-func (s StubSessionManager) CreateAccepted(ctx context.Context, opts session.CreateOpts) (*session.Info, error) {
+func (s StubSessionManager) CreateAccepted(
+	ctx context.Context,
+	opts session.CreateAcceptedOpts,
+) (*session.Info, error) {
 	if s.CreateAcceptedFn != nil {
 		return s.CreateAcceptedFn(ctx, opts)
 	}
-	created, err := s.Create(ctx, opts)
+	if strings.TrimSpace(opts.InitialPrompt) != "" {
+		return nil, errors.New("testutil: CreateAcceptedFn is required for an initial prompt")
+	}
+	created, err := s.Create(ctx, opts.Session)
 	if created == nil || err != nil {
 		return nil, err
 	}

internal/api/udsapi/transport_parity_integration_test.go

@@ -25,6 +25,7 @@ import (
 	apispec "github.com/compozy/agh/internal/api/spec"
 	automationpkg "github.com/compozy/agh/internal/automation"
 	aghconfig "github.com/compozy/agh/internal/config"
+	"github.com/compozy/agh/internal/session"
 	"github.com/compozy/agh/internal/store"
 	"github.com/compozy/agh/internal/testutil/acpmock"
 	e2etest "github.com/compozy/agh/internal/testutil/e2e"
@@ -529,6 +530,7 @@ func TestUDSTransportSessionProviderCreateReadMatchesHTTP(t *testing.T) {
 		AgentName:     transportUDSAutomationAgent,
 		Provider:      provider,
 		WorkspacePath: runtimeHarness.WorkspaceRoot,
+		Prompt:        "Continue delegated task run",
 	}, &created); err != nil {
 		t.Fatalf("UDS create session error = %v", err)
 	}
@@ -538,6 +540,18 @@ func TestUDSTransportSessionProviderCreateReadMatchesHTTP(t *testing.T) {
 	if created.Session.Provider != provider {
 		t.Fatalf("UDS create provider = %q, want %q", created.Session.Provider, provider)
 	}
+	if created.Session.State != session.StateStarting {
+		t.Fatalf("UDS accepted create state = %q, want %q", created.Session.State, session.StateStarting)
+	}
+	created.Session = waitForTransportSessionActive(t, ctx, runtimeHarness, created.Session)
+	waitForTransportTranscriptText(
+		t,
+		ctx,
+		runtimeHarness,
+		created.Session.ID,
+		"Continue delegated task run",
+		"Delegated task session responded.",
+	)
 
 	var udsDetail aghcontract.SessionResponse
 	if err := runtimeHarness.UDSJSON(
@@ -1886,6 +1900,56 @@ func joinTransportTranscript(messages []transcriptpkg.UIMessage) string {
 	return transcriptpkg.JoinUIMessageText(messages)
 }
 
+func waitForTransportTranscriptText(
+	t testing.TB,
+	ctx context.Context,
+	runtimeHarness *e2etest.RuntimeHarness,
+	sessionID string,
+	want ...string,
+) {
+	t.Helper()
+
+	waitCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+	ticker := time.NewTicker(25 * time.Millisecond)
+	defer ticker.Stop()
+	var (
+		lastText string
+		lastErr  error
+	)
+	for {
+		page, err := runtimeHarness.SessionTranscript(waitCtx, sessionID)
+		if err == nil {
+			lastText = joinTransportTranscript(transcriptpkg.MessagesFromEntries(page.Entries))
+			matched := true
+			for _, expected := range want {
+				if !strings.Contains(lastText, expected) {
+					matched = false
+					break
+				}
+			}
+			if matched {
+				return
+			}
+		} else {
+			lastErr = err
+		}
+
+		select {
+		case <-waitCtx.Done():
+			t.Fatalf(
+				"timed out waiting for session %q transcript text %q: %v; last error=%v transcript=%q",
+				sessionID,
+				want,
+				waitCtx.Err(),
+				lastErr,
+				lastText,
+			)
+		case <-ticker.C:
+		}
+	}
+}
+
 func transportMockFixturePath(t testing.TB, name string) string {
 	t.Helper()
 

internal/cli/session_create.go

@@ -7,33 +7,39 @@ import (
 	"github.com/spf13/cobra"
 )
 
+const sessionCreateExample = `  # Start a session in the current workspace using the configured default agent
+  agh session new
+
+  # Start a named session for a specific registered workspace and agent
+  agh session new --workspace checkout-api --agent reviewer --name review-api
+
+  # Override provider, model, and reasoning effort for this session only
+  agh session new --provider codex --model gpt-5.6-sol --reasoning-effort max
+
+  # Create the session and dispatch its first prompt after runtime activation
+  agh session new --prompt "Inspect the failing build and propose a fix"
+
+  # Auto-register an absolute workspace path before creating the session
+  agh session new --cwd "$PWD" --agent reviewer`
+
 func newSessionCreateCommand(deps commandDeps) *cobra.Command {
 	var (
 		agentName       string
 		cwd             string
 		name            string
 		provider        string
 		model           string
+		prompt          string
 		reasoningEffort string
 		workspaceRef    string
 		noWait          bool
 		networkFlags    networkParticipationFlags
 	)
 
 	cmd := &cobra.Command{
-		Use:   sessionNewKey,
-		Short: "Create a new session",
-		Example: `  # Start a session in the current workspace using the configured default agent
-  agh session new
-
-  # Start a named session for a specific registered workspace and agent
-  agh session new --workspace checkout-api --agent reviewer --name review-api
-
-  # Override provider, model, and reasoning effort for this session only
-  agh session new --provider codex --model gpt-5.6-sol --reasoning-effort max
-
-  # Auto-register an absolute workspace path before creating the session
-  agh session new --cwd "$PWD" --agent reviewer`,
+		Use:     sessionNewKey,
+		Short:   "Create a new session",
+		Example: sessionCreateExample,
 		RunE: func(cmd *cobra.Command, _ []string) error {
 			client, err := clientFromDeps(deps)
 			if err != nil {
@@ -54,6 +60,7 @@ func newSessionCreateCommand(deps commandDeps) *cobra.Command {
 				Provider:             strings.TrimSpace(provider),
 				Model:                strings.TrimSpace(model),
 				ReasoningEffort:      contract.ReasoningEffort(strings.TrimSpace(reasoningEffort)),
+				Prompt:               strings.TrimSpace(prompt),
 				Name:                 name,
 				Workspace:            workspace,
 				WorkspacePath:        workspacePath,
@@ -79,6 +86,7 @@ func newSessionCreateCommand(deps commandDeps) *cobra.Command {
 	bindNamedNetworkParticipationFlags(cmd, &networkFlags)
 	cmd.Flags().StringVar(&provider, sessionProviderKey, "", "Optional provider override for this session")
 	cmd.Flags().StringVar(&model, "model", "", "Optional model override for this session")
+	cmd.Flags().StringVar(&prompt, "prompt", "", "Initial prompt to dispatch after the session becomes active")
 	cmd.Flags().BoolVar(&noWait, "no-wait", false, "Return after the durable starting session is accepted")
 	cmd.Flags().StringVar(
 		&reasoningEffort,