fix: separate debug and development launch profiles (#2487)

apps/backend/Makefile

@@ -7,6 +7,16 @@ GO := go
 GOFLAGS := -v
 LDFLAGS := -s -w
 
+# Debug launches get a distinct browser identity by default. An explicit
+# environment or command-line value still wins through Make's `?=` semantics.
+KANDEV_WEB_TITLE_PREFIX ?= Debug
+
+# Quote the debug title prefix for the POSIX recipe. The replacement keeps
+# embedded single quotes safe while preserving spaces and shell metacharacters.
+single_quote := '
+single_quote_escape := '\''
+shell_quote = $(single_quote)$(subst $(single_quote),$(single_quote_escape),$(1))$(single_quote)
+
 # Cross-platform commands
 #
 # Two independent axes decide these variables; conflating them breaks Git
@@ -50,8 +60,8 @@ ifeq ($(OS)$(MSYSTEM),Windows_NT)
   GO_DARWIN_AMD64 = set CGO_ENABLED=0& set GOOS=darwin& set GOARCH=amd64&
   # Run-target env prefixes and binary invocation. cmd.exe has no `NAME=VAL cmd`
   # syntax (use `set NAME=VAL&`) and no `exec`; the binary path needs backslashes.
-  DEV_ENV = set KANDEV_DEBUG_PPROF_ENABLED=true&
-  DEBUG_ENV = set KANDEV_DEBUG_PPROF_ENABLED=true& set KANDEV_LOG_LEVEL=debug&
+  DEV_ENV = set KANDEV_DEBUG_DEV_MODE=true&
+  DEBUG_ENV = set KANDEV_DEBUG_PPROF_ENABLED=true& set KANDEV_LOG_LEVEL=debug& set "KANDEV_WEB_TITLE_PREFIX=$(KANDEV_WEB_TITLE_PREFIX)"&
   EXEC =
   RUN_BIN = "$(subst /,\,$(BUILD_DIR)/$(BINARY_NAME)$(EXE))"
   # check-make-shells is a bash script; native cmd.exe can't run its shebang, so
@@ -75,8 +85,8 @@ else
   GO_LINUX_ARM64 = CGO_ENABLED=0 GOOS=linux GOARCH=arm64
   GO_DARWIN_ARM64 = CGO_ENABLED=0 GOOS=darwin GOARCH=arm64
   GO_DARWIN_AMD64 = CGO_ENABLED=0 GOOS=darwin GOARCH=amd64
-  DEV_ENV = KANDEV_DEBUG_PPROF_ENABLED=true
-  DEBUG_ENV = KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug
+  DEV_ENV = KANDEV_DEBUG_DEV_MODE=true
+  DEBUG_ENV = KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX=$(call shell_quote,$(KANDEV_WEB_TITLE_PREFIX))
   EXEC = exec
   RUN_BIN = ./$(BUILD_DIR)/$(BINARY_NAME)$(EXE)
   CHECK_SHELLS = @../../scripts/check-make-shells

apps/backend/internal/launcher/env.go

@@ -5,6 +5,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"os"
+	"strings"
 )
 
 const healthTokenBytes = 32
@@ -30,6 +31,7 @@ func backendEnv(ports portConfig, logLevel, consoleLogLevel string, debug bool,
 	if debug {
 		env = upsertEnv(env, "KANDEV_DEBUG_AGENT_MESSAGES", "true")
 		env = upsertEnv(env, "KANDEV_DEBUG_PPROF_ENABLED", "true")
+		env = setEnvIfUnset(env, "KANDEV_WEB_TITLE_PREFIX", "Debug")
 	}
 	return env
 }
@@ -37,10 +39,20 @@ func backendEnv(ports portConfig, logLevel, consoleLogLevel string, debug bool,
 func upsertEnv(env []string, key, value string) []string {
 	prefix := key + "="
 	for i, item := range env {
-		if len(item) >= len(prefix) && item[:len(prefix)] == prefix {
+		if strings.HasPrefix(item, prefix) {
 			env[i] = prefix + value
 			return env
 		}
 	}
 	return append(env, prefix+value)
 }
+
+func setEnvIfUnset(env []string, key, value string) []string {
+	prefix := key + "="
+	for _, item := range env {
+		if strings.HasPrefix(item, prefix) {
+			return env
+		}
+	}
+	return append(env, prefix+value)
+}

apps/backend/internal/launcher/start_test.go

@@ -56,6 +56,24 @@ func TestBackendEnvCarriesIndependentThresholds(t *testing.T) {
 	}
 }
 
+func TestBackendEnvDebugDefaultsToDebugTitle(t *testing.T) {
+	unsetEnvForTest(t, "KANDEV_WEB_TITLE_PREFIX")
+
+	env := backendEnv(portConfig{BackendPort: 1234, AgentctlPort: 5678}, "debug", "warn", true, "health-token")
+	if got := envValue(env, "KANDEV_WEB_TITLE_PREFIX"); got != "Debug" {
+		t.Fatalf("KANDEV_WEB_TITLE_PREFIX = %q for debug launch; want %q", got, "Debug")
+	}
+}
+
+func TestBackendEnvDebugPreservesExplicitTitle(t *testing.T) {
+	t.Setenv("KANDEV_WEB_TITLE_PREFIX", "Custom")
+
+	env := backendEnv(portConfig{BackendPort: 1234, AgentctlPort: 5678}, "debug", "warn", true, "health-token")
+	if got := envValue(env, "KANDEV_WEB_TITLE_PREFIX"); got != "Custom" {
+		t.Fatalf("KANDEV_WEB_TITLE_PREFIX = %q for explicit debug launch; want %q", got, "Custom")
+	}
+}
+
 func TestNewHealthTokenIsFreshAndOpaque(t *testing.T) {
 	first, err := newHealthToken()
 	if err != nil {
@@ -192,3 +210,28 @@ func TestRunManagedAppAttachesSignalsBeforeBackendLaunch(t *testing.T) {
 		t.Fatalf("health token launched=%q waited=%q, want one shared non-empty token", launchedHealthToken, waitedHealthToken)
 	}
 }
+
+func envValue(env []string, key string) string {
+	prefix := key + "="
+	for _, item := range env {
+		if strings.HasPrefix(item, prefix) {
+			return strings.TrimPrefix(item, prefix)
+		}
+	}
+	return ""
+}
+
+func unsetEnvForTest(t *testing.T, key string) {
+	t.Helper()
+	value, wasSet := os.LookupEnv(key)
+	if err := os.Unsetenv(key); err != nil {
+		t.Fatalf("unset %s: %v", key, err)
+	}
+	t.Cleanup(func() {
+		if wasSet {
+			_ = os.Setenv(key, value)
+			return
+		}
+		_ = os.Unsetenv(key)
+	})
+}

apps/backend/internal/launcher/supervisor.go

@@ -176,6 +176,7 @@ func allowedSupervisorEnv(env []string) map[string]string {
 		"KANDEV_AGENT_STANDALONE_PORT": true,
 		"KANDEV_LOG_LEVEL":             true,
 		"KANDEV_CONSOLE_LOG_LEVEL":     true,
+		"KANDEV_WEB_TITLE_PREFIX":      true,
 		"KANDEV_DEBUG_DEV_MODE":        true,
 		"KANDEV_DEBUG_AGENT_MESSAGES":  true,
 		"KANDEV_DEBUG_PPROF_ENABLED":   true,

apps/backend/internal/launcher/supervisor_test.go

@@ -13,6 +13,7 @@ func TestBuildManifestUsesSameBinaryBackendMode(t *testing.T) {
 		"KANDEV_SERVER_PORT=1234",
 		"KANDEV_DESKTOP_HEALTH_TOKEN=health-token",
 		"KANDEV_CONSOLE_LOG_LEVEL=warn",
+		"KANDEV_WEB_TITLE_PREFIX=Debug",
 		"UNRELATED=value",
 	}
 	manifest := buildManifest("/opt/kandev/bin/kandev", []string{"__backend"}, "/opt/kandev/bin", env, "/tmp/home", 1234, "run")
@@ -35,6 +36,9 @@ func TestBuildManifestUsesSameBinaryBackendMode(t *testing.T) {
 	if manifest.Env["KANDEV_DESKTOP_HEALTH_TOKEN"] != "health-token" {
 		t.Fatalf("KANDEV_DESKTOP_HEALTH_TOKEN = %q", manifest.Env["KANDEV_DESKTOP_HEALTH_TOKEN"])
 	}
+	if manifest.Env["KANDEV_WEB_TITLE_PREFIX"] != "Debug" {
+		t.Fatalf("KANDEV_WEB_TITLE_PREFIX = %q", manifest.Env["KANDEV_WEB_TITLE_PREFIX"])
+	}
 }
 
 func TestPrepareSupervisorEnvWritesExpectedPaths(t *testing.T) {

apps/backend/internal/profiles/profiles.go

@@ -69,7 +69,7 @@ func DetectEnvironment() Environment {
 	if isTruthy(os.Getenv("KANDEV_E2E_MOCK")) {
 		return EnvE2E
 	}
-	if isTruthy(os.Getenv("KANDEV_DEBUG_DEV_MODE")) || isTruthy(os.Getenv("KANDEV_DEBUG_PPROF_ENABLED")) {
+	if isTruthy(os.Getenv("KANDEV_DEBUG_DEV_MODE")) {
 		return EnvDev
 	}
 	return EnvProd

apps/backend/internal/profiles/profiles.yaml

@@ -134,8 +134,8 @@ debug:
     dev:  "true"
     e2e:  ""
 
-  # Legacy alias for KANDEV_DEBUG_DEV_MODE — kept for compatibility
-  # with older deploy scripts that grep for "pprof".
+  # Legacy debug behavior variable — kept for compatibility with older
+  # deploy scripts that enable pprof. It does not select the dev profile.
   KANDEV_DEBUG_PPROF_ENABLED:
     prod: ""
     dev:  "true"

apps/backend/internal/profiles/profiles_test.go

@@ -94,6 +94,26 @@ func TestApplyProfile_DevUsesDevelopmentDefaults(t *testing.T) {
 	}
 }
 
+func TestApplyProfile_PprofDebugKeepsProductionProfile(t *testing.T) {
+	clearProfileSelectors(t)
+	clearProfilesYAMLVars(t)
+	t.Setenv("KANDEV_DEBUG_PPROF_ENABLED", "true")
+
+	_, env, err := ApplyProfile()
+	if err != nil {
+		t.Fatalf("ApplyProfile: %v", err)
+	}
+	if env != EnvProd {
+		t.Fatalf("env = %q with pprof-only debug; want %q", env, EnvProd)
+	}
+	if v := os.Getenv("KANDEV_FEATURES_OFFICE"); v != "false" {
+		t.Errorf("KANDEV_FEATURES_OFFICE = %q with pprof-only debug; want %q", v, "false")
+	}
+	if _, ok := os.LookupEnv("KANDEV_WEB_TITLE_PREFIX"); ok {
+		t.Error("KANDEV_WEB_TITLE_PREFIX was set by the production profile; want it unset")
+	}
+}
+
 func TestApplyProfile_ExplicitTitlePrefixWinsInDev(t *testing.T) {
 	clearProfileSelectors(t)
 	clearProfilesYAMLVars(t)

apps/web/e2e/tests/system/title-prefix.spec.ts

@@ -1,6 +1,22 @@
 import { expect, test } from "../../fixtures/test-base";
 
 test.describe.serial("environment browser title prefixes", () => {
+  test("uses Debug for a diagnostics-only production profile", async ({ backend, testPage }) => {
+    await backend.restart({
+      KANDEV_E2E_MOCK: "",
+      KANDEV_DEBUG_DEV_MODE: "",
+      KANDEV_DEBUG_PPROF_ENABLED: "true",
+      KANDEV_WEB_TITLE_PREFIX: "Debug",
+    });
+
+    try {
+      await testPage.goto("/");
+      await expect(testPage).toHaveTitle("Debug Kandev");
+    } finally {
+      await backend.restart();
+    }
+  });
+
   test("uses Dev for the development profile", async ({ backend, testPage }) => {
     await backend.restart({ KANDEV_E2E_MOCK: "", KANDEV_DEBUG_DEV_MODE: "true" });
 

docs/configuration.md

@@ -34,9 +34,10 @@ All env vars use the `KANDEV_` prefix. Nested keys map by replacing `.` with `_`
 
 The aliases on the right are explicit bindings - see `LoadWithPath` in `config.go` for the full list. New keys should follow the deterministic rule (`KANDEV_<SECTION>_<KEYUPPERCASE>`) unless there is a reason to add an alias.
 
-The `make dev` launcher uses `Dev` as the default browser title prefix, and PR
-preview environments use `Preview`. An explicit `KANDEV_WEB_TITLE_PREFIX`
-value overrides those environment defaults.
+The `make dev` launcher uses `Dev` as the default browser title prefix. The
+`make start-debug` launcher keeps production defaults, enables diagnostics, and
+uses `Debug`. PR preview environments use `Preview`. An explicit
+`KANDEV_WEB_TITLE_PREFIX` value overrides those environment defaults.
 
 ## Full `config.yaml` example
 

docs/decisions/0007-runtime-feature-flags.md

@@ -57,9 +57,15 @@ Top-level sections are purely for human readability (the loader walks every leaf
 | signal | profile | who sets it |
 |---|---|---|
 | `KANDEV_E2E_MOCK=true` | `e2e` | `apps/web/e2e/fixtures/backend.ts` |
-| `KANDEV_DEBUG_DEV_MODE=true` (or `…_PPROF_ENABLED=true`) | `dev` | `apps/cli/src/dev.ts` |
+| `KANDEV_DEBUG_DEV_MODE=true` | `dev` | `apps/cli/src/dev.ts`, the `make dev` backend target |
 | (neither) | `prod` | the default for any other launch |
 
+`KANDEV_DEBUG_PPROF_ENABLED` is a legacy debug behavior variable. It enables
+pprof when a launcher sets it, but it does not select the `dev` profile. This
+keeps `make start-debug` on the production profile while it retains debug
+diagnostics; that launcher supplies the explicit `Debug` title prefix. See
+[ADR-2026-08-10-debug-launcher-profile-selection](2026-08-10-debug-launcher-profile-selection.md).
+
 `profiles.ApplyProfile()` then walks every leaf and calls `os.Setenv` **only when the var is not already set** and **only when the resolved value is non-empty**. Empty means "leave unset."
 
 This produces the precedence chain:

docs/decisions/2026-08-10-debug-launcher-profile-selection.md

@@ -0,0 +1,52 @@
+# ADR-2026-08-10: Keep Debug Launches on the Production Profile
+
+**Status:** accepted
+**Date:** 2026-08-10
+**Area:** backend, frontend, cli
+
+## Context
+
+The native `--debug` launcher sets `KANDEV_DEBUG_PPROF_ENABLED=true` and
+`KANDEV_DEBUG_AGENT_MESSAGES=true`. Profile detection also treated the pprof
+variable as the development-profile selector. As a result, `make start-debug`
+received development defaults and the `Dev Kandev` browser title.
+
+The debug launcher needs diagnostic behavior without development-only defaults.
+The source-checkout `make dev` path already has a canonical development
+selector, `KANDEV_DEBUG_DEV_MODE=true`.
+
+## Decision
+
+Use only `KANDEV_DEBUG_DEV_MODE=true` as the development-profile selector.
+Keep `KANDEV_DEBUG_PPROF_ENABLED` as a legacy behavior variable for pprof and
+related debug compatibility. It does not select the `dev` profile.
+
+The launch contracts are:
+
+- `make dev` selects `dev` and uses `Dev Kandev`.
+- `make start-debug` enables debug diagnostics, selects `prod`, and uses
+  `Debug Kandev` by default. An explicit title prefix still wins.
+- `KANDEV_E2E_MOCK=true` keeps its existing priority and selects `e2e`.
+
+The browser title continues to use `KANDEV_WEB_TITLE_PREFIX`. The debug
+launcher supplies `Debug` as its default prefix without adding a new profile.
+
+## Consequences
+
+Debugging a release-style build no longer enables development feature defaults
+or the development browser identity. It has the distinct `Debug Kandev` title
+while retaining production defaults. Contributors who need the development
+profile use `make dev` or set `KANDEV_DEBUG_DEV_MODE=true`.
+
+The legacy pprof variable remains available for older launch scripts. Tests and
+launcher checks must keep the selector and debug behavior separate.
+
+## Alternatives Considered
+
+1. Set only an empty title prefix in `make start-debug`. Rejected because it
+   fixes the browser label but leaves other development defaults enabled and
+   does not identify a diagnostics-only launch.
+2. Keep pprof as a profile selector. Rejected because pprof is a diagnostic
+   behavior, not a development-environment identity.
+3. Remove the pprof variable. Rejected because existing launchers and config
+   users depend on the compatibility alias.

docs/decisions/INDEX.md

@@ -142,3 +142,4 @@ Read individual ADRs for full context. Create new ones via `/record decision` or
 | 2026-08-08-task-owned-worktree-lifetime | [Keep Worktree Ownership at the Task Lifecycle](2026-08-08-task-owned-worktree-lifetime.md) | accepted | backend, frontend | 2026-08-08 |
 | 2026-08-09-bind-automation-mutations-to-event-targets | [Bind Automation Mutations to Event Targets](2026-08-09-bind-automation-mutations-to-event-targets.md) | accepted | backend, agentctl, protocol, security, workflow | 2026-08-09 |
 | 2026-08-09-exclusive-runtime-state-ownership | [Lock Runtime State Before Backend Startup](2026-08-09-exclusive-runtime-state-ownership.md) | accepted | backend, infra | 2026-08-09 |
+| 2026-08-10-debug-launcher-profile-selection | [Keep Debug Launches on the Production Profile](2026-08-10-debug-launcher-profile-selection.md) | accepted | backend, frontend, cli | 2026-08-10 |

docs/plans/debug-start-production-title/plan.md

@@ -0,0 +1,153 @@
+---
+spec: docs/specs/dev-preview-title-prefixes/spec.md
+created: 2026-08-10
+status: complete
+---
+
+# Implementation Plan: Keep Debug Start on the Production Profile
+
+## Overview
+
+`make start-debug` sets the legacy pprof debug variable. The profile loader
+currently treats that variable as a development selector, so it applies the
+`Dev` title prefix. Make `KANDEV_DEBUG_DEV_MODE` the only development selector,
+keep pprof as debug behavior, and preserve `Dev Kandev` for `make dev`. The
+debug launcher supplies `Debug` as the default title prefix, producing
+`Debug Kandev` without selecting the development profile.
+
+The work proceeds from the backend profile contract to the launcher checks and
+then to the browser regression test and public documentation.
+
+The confirmed root cause is in `profiles.DetectEnvironment`: its dev branch
+checks `KANDEV_DEBUG_PPROF_ENABLED` even though the release debug launcher sets
+that variable without selecting the development profile.
+
+## Backend and launchers
+
+### Profile selection
+
+- `apps/backend/internal/profiles/profiles.go`: make
+  `KANDEV_DEBUG_DEV_MODE=true` the only non-e2e signal for the `dev` profile.
+  Keep `KANDEV_DEBUG_PPROF_ENABLED` available to the debug configuration and
+  pprof routes.
+- `apps/backend/internal/profiles/profiles_test.go`: add a pprof-only
+  regression case that resolves to `prod`, keeps the title prefix out of the
+  profile defaults, and keeps production feature defaults.
+
+### Debug title default
+
+- `apps/backend/internal/launcher/env.go`: when the native debug launcher is
+  used, supply `KANDEV_WEB_TITLE_PREFIX=Debug` only when the caller has not
+  already supplied a prefix. Keep the explicit environment override contract.
+- `apps/backend/internal/launcher/start_test.go`: verify the debug launcher
+  supplies `Debug` by default and preserves an explicit prefix.
+- `apps/backend/internal/launcher/supervisor.go`: preserve the title prefix in
+  the restart manifest so a supervised restart keeps `Debug Kandev`.
+- `apps/backend/internal/launcher/supervisor_test.go`: cover the allowlisted
+  title prefix in the restart manifest.
+
+### Make targets
+
+- `apps/backend/Makefile`: make the direct `dev` target export the canonical
+  `KANDEV_DEBUG_DEV_MODE=true` selector. Make the direct `start-debug` target
+  default to the `Debug` prefix while preserving an explicitly supplied
+  `KANDEV_WEB_TITLE_PREFIX`. The debug target continues to export pprof and
+  debug logging without the dev selector.
+- `scripts/check-make-shells`: update the expected `dev` command for Unix,
+  native Windows, and Git Bash/MSYS, plus the direct `start-debug` title
+  environment.
+
+### Durable decision record
+
+- `docs/decisions/0007-runtime-feature-flags.md`: reconcile the profile
+  selector table with the corrected contract.
+- `docs/decisions/2026-08-10-debug-launcher-profile-selection.md`: preserve the
+  reason for separating diagnostic behavior from environment identity.
+- `docs/decisions/INDEX.md`: index the new decision.
+
+## Frontend
+
+No frontend production code changes are required. The existing server-shell
+and SPA title composition already uses `KANDEV_WEB_TITLE_PREFIX` correctly.
+
+The existing title-prefix browser test will cover the debug-start result. This
+is browser metadata, not a layout or interaction surface. Desktop and phone
+viewports therefore have the same expected title, and no mobile-specific
+interaction test is required.
+
+## Public documentation
+
+- `docs/public/configuration.md`: state that `make start-debug` keeps the
+  production profile and uses the `Debug Kandev` title while enabling
+  diagnostics.
+- `docs/public/cli.md`: explain that `--debug` does not select the development
+  profile; `make dev` is the development-profile launcher.
+- `docs/configuration.md`: keep the internal configuration reference aligned.
+
+## Tests
+
+- **What:** pprof-only startup selects `prod` and does not apply `Dev`.
+  **File:** `apps/backend/internal/profiles/profiles_test.go`.
+  **How:** isolated environment unit test through `ApplyProfile`.
+- **What:** the native debug launcher supplies the `Debug` prefix by default
+  and preserves an explicit prefix.
+  **File:** `apps/backend/internal/launcher/start_test.go`.
+  **How:** inspect the environment assembled for debug and non-debug starts.
+- **What:** supervised restarts preserve the debug title prefix.
+  **File:** `apps/backend/internal/launcher/supervisor_test.go`.
+  **How:** assert the debug prefix survives the restart manifest allowlist.
+- **What:** direct `make dev` emits the canonical dev selector across shells.
+  **File:** `scripts/check-make-shells`.
+  **How:** run the existing deterministic `make -n` shell matrix.
+- **What:** the debug-start launcher uses the distinct debug title.
+  **File:** `apps/web/e2e/tests/system/title-prefix.spec.ts`.
+  **How:** restart the fixture with pprof enabled and both profile selectors
+  disabled plus the launcher's `Debug` prefix, navigate to `/`, and assert
+  `Debug Kandev`.
+- **What:** development and preview title behavior remains unchanged.
+  **File:** `apps/web/e2e/tests/system/title-prefix.spec.ts`.
+  **How:** retain the existing `Dev Kandev` and `Preview Kandev` assertions.
+
+## E2E Tests
+
+- **Scenario:** GIVEN a backend restarted with pprof/debug behavior and no
+  development or e2e selector, WHEN the browser opens Kandev, THEN the title is
+  `Debug Kandev`.
+- **Scenario:** GIVEN a backend restarted with the development selector, WHEN
+  the browser opens Kandev, THEN the title is `Dev Kandev`.
+- **Scenario:** GIVEN a backend with an explicit `Preview` prefix, WHEN the
+  browser opens Kandev, THEN the title is `Preview Kandev`.
+- **File:** `apps/web/e2e/tests/system/title-prefix.spec.ts`.
+- **Mobile note:** `document.title` is viewport-independent. The existing
+  browser metadata assertion covers the same user outcome on a phone, so no
+  `mobile-*.spec.ts` file is needed.
+
+## Verification Results
+
+- `make test-backend` — passed (full backend test suite).
+- `make lint-backend` — passed (0 issues).
+- `make build-backend` — passed (backend binaries built).
+- `cd apps/backend && make check-make-shells` — passed for Unix, native
+  Windows, and Git Bash/MSYS dispatch, including explicit prefixes with spaces.
+- `cd apps/web && pnpm e2e:run --project chromium tests/system/title-prefix.spec.ts`
+  — passed (3 tests).
+- `node --test scripts/validate-public-docs.test.mjs` — passed (58 tests).
+- `node scripts/validate-public-docs.mjs` — passed (41 published docs pages).
+- `git diff --check` — passed.
+
+## Implementation Waves And Parallel Candidates
+
+Wave 1 (sequential):
+
+- [x] [task-01-profile-selector-contract](task-01-profile-selector-contract.md)
+
+Wave 2 (sequential, depends on Wave 1):
+
+- [x] [task-02-title-regression-docs](task-02-title-regression-docs.md)
+
+Parallel delegation is not authorized by this plan. The work stays in the
+primary session and follows the dependency order above.
+
+## Open Questions
+
+None.

docs/plans/debug-start-production-title/task-01-profile-selector-contract.md

@@ -0,0 +1,77 @@
+---
+id: "01-profile-selector-contract"
+title: "Separate debug profile selector"
+status: done
+wave: 1
+depends_on: []
+plan: "plan.md"
+spec: "../../specs/dev-preview-title-prefixes/spec.md"
+---
+
+# Task 01: Separate debug profile selector
+
+## Acceptance
+
+- `KANDEV_DEBUG_PPROF_ENABLED=true` without `KANDEV_DEBUG_DEV_MODE=true` selects
+  `prod` and does not receive the `Dev` profile prefix.
+- `KANDEV_DEBUG_DEV_MODE=true` still selects `dev` and supplies the `Dev`
+  title prefix.
+- The native and direct backend `start-debug` launchers supply the `Debug`
+  prefix by default, while preserving an explicit prefix.
+- A supervised backend restart preserves the configured title prefix.
+- The direct backend `dev` target exports `KANDEV_DEBUG_DEV_MODE=true`, while
+  `start-debug` retains pprof and debug logging without that selector.
+- The profile ADR and its index describe the corrected boundary.
+
+## Verification
+
+- `make test-backend`
+- `make lint-backend`
+- `make build-backend`
+- `make check-make-shells`
+- `git diff --check`
+
+## Files likely touched
+
+- `apps/backend/internal/profiles/profiles.go`
+- `apps/backend/internal/profiles/profiles_test.go`
+- `apps/backend/internal/launcher/env.go`
+- `apps/backend/internal/launcher/start_test.go`
+- `apps/backend/internal/launcher/supervisor.go`
+- `apps/backend/internal/launcher/supervisor_test.go`
+- `apps/backend/Makefile`
+- `scripts/check-make-shells`
+- `docs/decisions/0007-runtime-feature-flags.md`
+- `docs/decisions/2026-08-10-debug-launcher-profile-selection.md`
+- `docs/decisions/INDEX.md`
+
+## Dependencies
+
+None.
+
+## Parallelism
+
+Sequential. The profile selector and launcher environment are one shared
+startup contract.
+
+## Inputs
+
+- The `What`, API surface, failure modes, and scenarios in the repair spec.
+- The confirmed root cause in `plan.md`.
+- `profiles.DetectEnvironment`, `profiles.ApplyProfile`, and the existing shell
+  dispatch harness.
+
+## Output contract
+
+Report the changed files, exact test commands and results, any risks, and the
+updated task and plan statuses in the same conversation. Do not delegate this
+task to a subagent without explicit user authorization.
+
+## Results
+
+- `make test-backend` — passed (full backend test suite).
+- `make lint-backend` — passed (0 issues).
+- `make build-backend` — passed (backend binaries built).
+- `make check-make-shells` — passed (Unix, native Windows, and Git Bash/MSYS
+  dispatch, including explicit prefixes with spaces).
+- `git diff --check` — passed.

docs/plans/debug-start-production-title/task-02-title-regression-docs.md

@@ -0,0 +1,67 @@
+---
+id: "02-title-regression-docs"
+title: "Prove debug title behavior"
+status: done
+wave: 2
+depends_on: ["01-profile-selector-contract"]
+plan: "plan.md"
+spec: "../../specs/dev-preview-title-prefixes/spec.md"
+---
+
+# Task 02: Prove debug title behavior
+
+## Acceptance
+
+- The title-prefix E2E test asserts `Debug Kandev` for a pprof/debug restart
+  without development or e2e profile selectors.
+- The existing `Dev Kandev` and `Preview Kandev` assertions continue to pass.
+- Public and internal configuration docs explain the different `make dev` and
+  `make start-debug` title behavior.
+- The viewport-independent metadata behavior has an explicit mobile-parity
+  justification. No touch or layout surface changes.
+
+## Verification
+
+- `cd apps/web && pnpm e2e:run --project chromium tests/system/title-prefix.spec.ts`
+- `node --test scripts/validate-public-docs.test.mjs`
+- `node scripts/validate-public-docs.mjs`
+- `git diff --check`
+
+If the fresh worktree has no frontend dependencies, first run
+`cd apps && pnpm install --frozen-lockfile`.
+
+## Files likely touched
+
+- `apps/web/e2e/tests/system/title-prefix.spec.ts`
+- `docs/public/configuration.md`
+- `docs/public/cli.md`
+- `docs/configuration.md`
+
+## Dependencies
+
+Task 01 must pass before this task starts.
+
+## Parallelism
+
+Sequential. The browser assertion depends on the profile-selector behavior.
+
+## Inputs
+
+- The title scenarios in `docs/specs/dev-preview-title-prefixes/spec.md`.
+- The mobile-parity conclusion in `plan.md`.
+- Existing fixture restart behavior in `apps/web/e2e/fixtures/backend.ts`.
+
+## Output contract
+
+Report the changed files, exact E2E and documentation checks, cleanup status,
+and the updated task and plan statuses in the same conversation.
+
+## Results
+
+- `cd apps/web && pnpm e2e:run --project chromium tests/system/title-prefix.spec.ts`
+  — passed (3 tests: Debug, Dev, and Preview titles).
+- `node --test scripts/validate-public-docs.test.mjs` — passed (58 tests).
+- `node scripts/validate-public-docs.mjs` — passed (41 published docs pages).
+- `cd apps && pnpm exec prettier --check web/e2e/tests/system/title-prefix.spec.ts`
+  — passed.
+- `git diff --check` — passed.

docs/public/cli.md

@@ -251,7 +251,15 @@ Flags take precedence over the equivalent port variables. `KANDEV_BACKEND_PORT`
 
 The launcher also sets the selected server and `agentctl` ports for the backend. Treat its supervisor socket and manifest under `<home>/supervisor/` as private implementation state, not a control API.
 
-`--debug` sets `KANDEV_DEBUG_AGENT_MESSAGES=true` and `KANDEV_DEBUG_PPROF_ENABLED=true`. Debug events go to `<home>/logs/backend-logs.log`; warn and above still appear on stdout. ACP logs can contain full prompts, file content, and tool calls, while diagnostic endpoints expose process details. Use debug mode only on a trusted machine and remove retained debug logs afterward. [Configuration](./configuration.md) lists locations and retention.
+`--debug` sets `KANDEV_DEBUG_AGENT_MESSAGES=true` and
+`KANDEV_DEBUG_PPROF_ENABLED=true` without selecting the `dev` profile. The
+`make start-debug` launcher also defaults the browser title to `Debug Kandev`;
+`make dev` selects the development profile and uses `Dev Kandev`. Debug events
+go to `<home>/logs/backend-logs.log`; warn and above still appear on stdout.
+ACP logs can contain full prompts, file content, and tool calls, while
+diagnostic endpoints expose process details. Use debug mode only on a trusted
+machine and remove retained debug logs afterward. [Configuration](./configuration.md)
+lists locations and retention.
 
 ## Data and cleanup
 

docs/public/configuration.md

@@ -58,7 +58,7 @@ Some common camelCase keys have explicit compatibility aliases. Use the document
 | `server.readTimeout` | `KANDEV_SERVER_READTIMEOUT` | `30` | HTTP read timeout in seconds. |
 | `server.writeTimeout` | `KANDEV_SERVER_WRITETIMEOUT` | `30` | HTTP write timeout in seconds. |
 | `server.webInternalUrl` | `KANDEV_WEB_INTERNAL_URL` | empty | Development reverse-proxy target for a separately running web app. Installed releases normally serve embedded assets. |
-| `server.webTitlePrefix` | `KANDEV_WEB_TITLE_PREFIX` | empty | Prefixes the browser tab title as `<prefix> Kandev` (for example `TEST` renders `TEST Kandev`), so several instances stay distinguishable in adjacent tabs. `make dev` defaults to `Dev`; PR previews use `Preview`. An explicit value overrides these defaults. Empty keeps the plain `Kandev` title. |
+| `server.webTitlePrefix` | `KANDEV_WEB_TITLE_PREFIX` | empty | Prefixes the browser tab title as `<prefix> Kandev` (for example `TEST` renders `TEST Kandev`), so several instances stay distinguishable in adjacent tabs. `make dev` defaults to `Dev`; `make start-debug` keeps production defaults, enables diagnostics, and defaults to `Debug`; PR previews use `Preview`. An explicit value overrides these defaults. Empty keeps the plain `Kandev` title. |
 
 The default host exposes the server on every interface even though the CLI prints a `localhost` URL. The current local product path must not be treated as an authenticated multi-user perimeter. For remote access, bind to loopback and use a trusted authenticated tunnel/proxy, or isolate the network at the deployment layer.
 
@@ -170,9 +170,17 @@ Discovery roots bound automatic filesystem traversal, so scope them narrowly. Th
 | YAML key | Environment variable | Default | Current behavior |
 |---|---|---|---|
 | `debug.devMode` | `KANDEV_DEBUG_DEV_MODE` | `false` | Enables diagnostic endpoints and agent-message debug logging. |
-| `debug.pprofEnabled` | `KANDEV_DEBUG_PPROF_ENABLED` | `false` | Legacy alias; also enables debug mode. |
+| `debug.pprofEnabled` | `KANDEV_DEBUG_PPROF_ENABLED` | `false` | Legacy diagnostics switch. It enables pprof behavior but does not select the `dev` profile. |
 
-Debug mode is high risk. It enables local diagnostic surfaces and implies `KANDEV_DEBUG_AGENT_MESSAGES=true` and `KANDEV_DEBUG_PPROF_ENABLED=true` when not explicitly locked by the environment. ACP JSONL frames include complete prompts, file content, and tool calls. Do not enable it on a shared or network-exposed backend.
+`KANDEV_DEBUG_DEV_MODE=true` selects the `dev` profile. `make dev` sets that
+selector and defaults the browser title to `Dev Kandev`. `make start-debug`
+enables pprof and debug logging without selecting the `dev` profile, and
+defaults the browser title to `Debug Kandev`. Debug mode is high risk. It
+enables local diagnostic surfaces and implies
+`KANDEV_DEBUG_AGENT_MESSAGES=true` and `KANDEV_DEBUG_PPROF_ENABLED=true` when
+not explicitly locked by the environment. ACP JSONL frames include complete
+prompts, file content, and tool calls. Do not enable it on a shared or
+network-exposed backend.
 
 ## Minimal examples
 
@@ -304,7 +312,7 @@ Copying this entire file is unnecessary and can freeze old defaults in a deploym
 | `features.auth` | `KANDEV_FEATURES_AUTH` | off | Authentication and per-user workspaces for the whole install. |
 | `features.claudeBackgroundPromptHandoff` | `KANDEV_FEATURES_CLAUDE_BACKGROUND_PROMPT_HANDOFF` | off | High-risk Claude Code experiment that exposes recognized background-only activity and admits a successor prompt. |
 | `features.claudeMidTurnSteering` | `KANDEV_FEATURES_CLAUDE_MID_TURN_STEERING` | off | High-risk Claude Code experiment that delivers a prompt into a still-generating turn (mid-turn steering) instead of queuing it, for agents advertising prompt queueing. |
-| `debug.devMode` | `KANDEV_DEBUG_DEV_MODE` (also locked by explicit legacy/debug-message vars) | off | High-risk diagnostic endpoints and ACP frame logging. |
+| `debug.devMode` | `KANDEV_DEBUG_DEV_MODE` | off | High-risk diagnostic endpoints and ACP frame logging. |
 
 UI changes are persisted in the database and require a restart. An explicitly set environment value wins and locks the UI control. Otherwise a database override wins over the embedded profile/default. Resetting a toggle removes its database override.
 

docs/specs/dev-preview-title-prefixes/spec.md

@@ -6,6 +6,8 @@ owner: Kandev
 
 # Environment-specific browser tab title prefixes
 
+The profile-selection boundary follows [ADR-2026-08-10-debug-launcher-profile-selection](../../decisions/2026-08-10-debug-launcher-profile-selection.md).
+
 ## Why
 
 Developers often keep a local development instance and one or more pull-request
@@ -24,6 +26,9 @@ easy to use the wrong instance.
   contract.
 - A normal production/start launch with no explicit prefix keeps the plain
   `Kandev` title.
+- A debug start (`make start-debug`) can enable pprof and debug logging without
+  selecting the development profile. It uses the explicit prefix `Debug` by
+  default, so its title is `Debug Kandev`.
 - The prefix is present both on the initial server-rendered page and after a
   client boot from `/api/v1/app-state`, using the title behavior delivered by
   PR #2459.
@@ -37,6 +42,7 @@ The existing environment contract remains the public configuration surface:
 |---|---|---|
 | Development profile (`make dev`) | `Dev` by default | `Dev Kandev` |
 | PR preview launcher | `Preview` | `Preview Kandev` |
+| Debug start (`make start-debug`) | `Debug` by default | `Debug Kandev` |
 | Normal start with no override | unset | `Kandev` |
 | Any launch with an explicit override | caller value | `<value> Kandev` |
 
@@ -46,6 +52,9 @@ not changed from the Kandev UI.
 ## Failure modes
 
 - If the prefix is unset or blank, the title remains `Kandev`.
+- `KANDEV_DEBUG_PPROF_ENABLED=true` enables legacy pprof behavior but does not
+  select the development profile or add the `Dev` prefix. The debug launcher
+  supplies the `Debug` prefix unless the caller supplies another prefix.
 - If the preview launcher cannot set the environment variable, the preview
   falls back to the existing plain-title behavior rather than failing startup.
 - If a supervised restart occurs, the launcher preserves the allowlisted prefix
@@ -69,11 +78,14 @@ caller supplies the same environment or profile again.
   the backend starts, **THEN** the browser title is `Custom Kandev`.
 - **GIVEN** a normal start with no title-prefix environment variable, **WHEN**
   the user opens Kandev, **THEN** the browser title is `Kandev`.
+- **GIVEN** a debug start with pprof and debug logging enabled but without the
+  development-profile selector, **WHEN** the user opens Kandev, **THEN** the
+  browser title is `Debug Kandev`.
 - **GIVEN** a preview or development backend with a configured prefix, **WHEN**
   its supervisor restarts the backend, **THEN** the browser title retains the
   same prefix.
 - **GIVEN** a phone-sized browser viewport, **WHEN** either environment is
-  opened, **THEN** the same title is shown; no viewport-specific interaction is
+  opened, **THEN** the same title is shown. No viewport-specific interaction is
   required.
 
 ## Out of scope

scripts/check-make-shells

@@ -29,7 +29,7 @@ status=0
 
 # expect <label> <OS> <MSYSTEM> <target> <expected recipe tail>
 expect() {
-	local label=$1 os=$2 msys=$3 target=$4 want=$5 marker=${6:-__backend} got
+	local label=$1 os=$2 msys=$3 target=$4 want=$5 marker=${6:-__backend} title_prefix=${7:-} got
 	# The OS=/MSYSTEM= overrides only steer which branch the Makefile picks;
 	# $(shell ...) still runs under this harness's POSIX shell, and it expands
 	# even under `make -n`. So neutralise the build-stamp probes rather than let
@@ -38,10 +38,17 @@ expect() {
 	# NULL_REDIR (rather than passing /dev/null) also dodges Git Bash rewriting
 	# a /dev/null argument to `nul` on its way to native make. None of this
 	# affects the run/dev/start-debug recipes under assertion.
-	got=$(make -C "$backend_dir" OS="$os" MSYSTEM="$msys" NULL_REDIR= BUILD_TIME=simulated -n "$target" 2>/dev/null \
-		| grep -F "$marker" \
-		| sed 's/^[[:space:]]*//; s/[[:space:]]*$//; s/[[:space:]]\{1,\}/ /g' \
-		|| true)
+	if [ -n "$title_prefix" ]; then
+		got=$(KANDEV_WEB_TITLE_PREFIX="$title_prefix" make -C "$backend_dir" OS="$os" MSYSTEM="$msys" NULL_REDIR= BUILD_TIME=simulated -n "$target" 2>/dev/null \
+			| grep -F "$marker" \
+			| sed 's/^[[:space:]]*//; s/[[:space:]]*$//; s/[[:space:]]\{1,\}/ /g' \
+			|| true)
+	else
+		got=$(env -u KANDEV_WEB_TITLE_PREFIX make -C "$backend_dir" OS="$os" MSYSTEM="$msys" NULL_REDIR= BUILD_TIME=simulated -n "$target" 2>/dev/null \
+			| grep -F "$marker" \
+			| sed 's/^[[:space:]]*//; s/[[:space:]]*$//; s/[[:space:]]\{1,\}/ /g' \
+			|| true)
+	fi
 	if [ "$got" = "$want" ]; then
 		printf 'ok    %-16s %-12s %s\n' "$label" "$target" "$got"
 	else
@@ -53,18 +60,24 @@ expect() {
 
 # Unix — no .exe, POSIX env-prefix + exec.
 expect unix '' '' run         './bin/kandev __backend'
-expect unix '' '' dev         'KANDEV_DEBUG_PPROF_ENABLED=true exec ./bin/kandev __backend'
-expect unix '' '' start-debug 'KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug exec ./bin/kandev __backend'
+expect unix '' '' dev         'KANDEV_DEBUG_DEV_MODE=true exec ./bin/kandev __backend'
+expect unix '' '' start-debug "KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX='Debug' exec ./bin/kandev __backend"
+expect unix '' '' start-debug "KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX='Preview' exec ./bin/kandev __backend" __backend Preview
+expect unix '' '' start-debug "KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX='QA Debug' exec ./bin/kandev __backend" __backend "QA Debug"
 
 # Native Windows (cmd/PowerShell) — .exe, `set VAR=VAL&`, backslash path, no exec.
 expect windows-native Windows_NT '' run         '"bin\kandev.exe" __backend'
-expect windows-native Windows_NT '' dev         'set KANDEV_DEBUG_PPROF_ENABLED=true& "bin\kandev.exe" __backend'
-expect windows-native Windows_NT '' start-debug 'set KANDEV_DEBUG_PPROF_ENABLED=true& set KANDEV_LOG_LEVEL=debug& "bin\kandev.exe" __backend'
+expect windows-native Windows_NT '' dev         'set KANDEV_DEBUG_DEV_MODE=true& "bin\kandev.exe" __backend'
+expect windows-native Windows_NT '' start-debug 'set KANDEV_DEBUG_PPROF_ENABLED=true& set KANDEV_LOG_LEVEL=debug& set "KANDEV_WEB_TITLE_PREFIX=Debug"& "bin\kandev.exe" __backend'
+expect windows-native Windows_NT '' start-debug 'set KANDEV_DEBUG_PPROF_ENABLED=true& set KANDEV_LOG_LEVEL=debug& set "KANDEV_WEB_TITLE_PREFIX=Preview"& "bin\kandev.exe" __backend' __backend Preview
+expect windows-native Windows_NT '' start-debug 'set KANDEV_DEBUG_PPROF_ENABLED=true& set KANDEV_LOG_LEVEL=debug& set "KANDEV_WEB_TITLE_PREFIX=QA Debug"& "bin\kandev.exe" __backend' __backend "QA Debug"
 
 # Git Bash/MSYS — .exe suffix but POSIX syntax (recipes run through sh).
 expect git-bash Windows_NT MINGW64 run         './bin/kandev.exe __backend'
-expect git-bash Windows_NT MINGW64 dev         'KANDEV_DEBUG_PPROF_ENABLED=true exec ./bin/kandev.exe __backend'
-expect git-bash Windows_NT MINGW64 start-debug 'KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug exec ./bin/kandev.exe __backend'
+expect git-bash Windows_NT MINGW64 dev         'KANDEV_DEBUG_DEV_MODE=true exec ./bin/kandev.exe __backend'
+expect git-bash Windows_NT MINGW64 start-debug "KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX='Debug' exec ./bin/kandev.exe __backend"
+expect git-bash Windows_NT MINGW64 start-debug "KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX='Preview' exec ./bin/kandev.exe __backend" __backend Preview
+expect git-bash Windows_NT MINGW64 start-debug "KANDEV_DEBUG_PPROF_ENABLED=true KANDEV_LOG_LEVEL=debug KANDEV_WEB_TITLE_PREFIX='QA Debug' exec ./bin/kandev.exe __backend" __backend "QA Debug"
 
 # deadcode — the analyzer is invoked through the same shell-specific env-prefix
 # mechanism, but its command has no __backend marker, so match its module path.