// Package execenv manages isolated per-task execution environments for the daemon.
// Each task gets its own directory with injected context files. Repositories are
// checked out on demand by the agent via `multica repo checkout`.
package execenv

import (
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/multica-ai/multica/server/internal/runtimeapps"
)

// RepoContextForEnv describes a workspace repo available for checkout.
type RepoContextForEnv struct {
	URL         string // remote URL
	Description string // optional repo description
	Ref         string // optional default checkout ref for this task
}

// ProjectResourceForEnv describes a single resource attached to the issue's
// project. The resource_ref payload is type-specific JSON; the agent reads
// resources.json on disk for the full structure. This struct only carries
// fields the meta-skill template needs to render a human-readable summary
// (URL for github_repo, generic label otherwise).
type ProjectResourceForEnv struct {
	ID           string          `json:"id"`              // server-assigned UUID
	ResourceType string          `json:"resource_type"`   // e.g. "github_repo"
	ResourceRef  json.RawMessage `json:"resource_ref"`    // raw JSONB payload from the API
	Label        string          `json:"label,omitempty"` // optional user-supplied label
}

// PrepareParams holds all inputs needed to set up an execution environment.
type PrepareParams struct {
	WorkspacesRoot  string // base path for all envs (e.g., ~/multica_workspaces)
	WorkspaceID     string // workspace UUID — stable identity and path suffix
	WorkspaceSlug   string // human-readable workspace path prefix
	TaskID          string // task UUID — stable identity and path suffix
	IssueIdentifier string // human-readable issue key (e.g. MUL-6063); empty for non-issue tasks
	AgentName       string // for git branch naming only
	// EnvRootPreclaimed says the CALLER already holds this env root's claim
	// (see ClaimEnvRoot) and has already reset it. Prepare then skips claiming.
	//
	// This exists because production preparation runs in a short-lived helper
	// process (PrepareIsolated): a lock taken here would be released by the
	// kernel the moment that helper exits, and the *os.File cannot cross the
	// JSON boundary back to the daemon. The claim therefore has to be held by
	// the parent, whose lifetime is the task run.
	EnvRootPreclaimed bool
	// Profile is the daemon's profile name (empty = default). It namespaces the
	// per-issue Codex session store so a second profile-daemon sharing the same
	// ~/.codex cannot see or GC this daemon's stores (MUL-4424).
	Profile      string
	Provider     string // agent provider (determines runtime config and skill injection paths)
	CodexVersion string // detected Codex CLI version (only used when Provider == "codex")
	OpenclawBin  string // resolved openclaw CLI path (only used when Provider == "openclaw"); empty = look up on PATH
	// McpConfig is the agent's saved `mcp_config` JSON, forwarded to the
	// provider-specific config preparer when that provider materialises MCP
	// via a per-task config file. Cursor, OpenClaw, and OMP consume it here;
	// other providers wire MCP via ExecOptions.McpConfig in the agent backend.
	McpConfig json.RawMessage
	// CursorMcpAuthSource is an explicit opt-in path to a Cursor mcp-auth.json
	// file, or the Cursor project data directory containing it. Only Cursor's
	// managed MCP path consumes it.
	CursorMcpAuthSource string
	// OpenclawGateway pins the OpenClaw Gateway endpoint inside the per-task
	// wrapper. Only consulted when Provider == "openclaw" and the agent's
	// runtime_config selected gateway mode (issue #3260). Zero means "inherit
	// whatever the user's global openclaw.json already configures".
	OpenclawGateway OpenclawGatewayPin
	// LocalWorkDir, when non-empty, redirects the agent's working directory
	// to a user-supplied absolute path instead of the synthesised envRoot/
	// workdir. The path is NOT copied or mounted — the agent operates on
	// the user's directory in place. The daemon still creates envRoot for
	// output/, logs/, and .gc_meta.json; only the workdir slot is
	// substituted. Used by the local_directory project_resource flow
	// (MUL-2663). When set, the envRoot/workdir directory is not created.
	LocalWorkDir string
	// LocalWorktree, when non-nil, is the worktree-mode counterpart of
	// LocalWorkDir: instead of running in the user's directory, the task gets
	// its own git worktree of that repo inside envRoot and delivers its work
	// as a branch. Tasks sharing the directory then run concurrently.
	// Mutually exclusive with LocalWorkDir — the daemon picks one based on the
	// resource's execution_mode.
	LocalWorktree *LocalWorktreeParams
	// HermesSourceHome is the shared Hermes home the per-task overlay is seeded
	// from — resolved by the daemon via execenv.ResolveHermesProfile so it honors
	// the agent's custom_env HERMES_HOME and any -p/--profile or sticky selection.
	// Only used for the hermes provider; empty falls back to the platform default.
	HermesSourceHome string
	// HermesSourceMustExist fails the overlay build closed when HermesSourceHome
	// is absent — set when an explicit named profile was requested so a typo
	// doesn't silently seed from an empty home and drop the user's auth/config.
	HermesSourceMustExist bool
	// HermesMemoryStore is the agent's persistent Hermes memory store
	// (HermesMemoryStorePath) the overlay links memories/ to, so memory outlives
	// the task. Empty keeps memories/ task-local — no agent to key on, or the
	// Multica profile dir could not be resolved.
	HermesMemoryStore string
	// HermesSessionStore is the conversation's persistent Hermes session store
	// (HermesSessionStorePath) used as HERMES_HOME, so the transcript
	// outlives the task and a follow-up turn can actually resume it. Empty keeps
	// state.db task-local — no agent or conversation to key on, or the Multica
	// profile dir could not be resolved.
	HermesSessionStore string
	// HermesEnv is the sanitized effective env (agent custom_env minus the daemon
	// blocklisted keys) used to expand ${VAR} in Hermes external_dirs so it
	// matches what the Hermes child process actually sees. Only used for hermes.
	HermesEnv map[string]string
	// ReasonixEnv is the sanitized agent custom_env, layered over the daemon's
	// own environment exactly as the child's env is built. The per-task
	// reasonix.toml restates the permissions from the user config that env
	// resolves to, so an agent that re-points (or clears) REASONIX_HOME moves the
	// daemon's read with it. Only used for reasonix.
	ReasonixEnv map[string]string
	// CodexCustomArgs are the effective Codex CLI args this task launches with
	// (daemon defaults + profile-fixed + per-agent custom_args). Only the
	// Windows sandbox decision reads them, to honor a `-c windows.sandbox=...`
	// override that never lands in config.toml (MUL-4957).
	CodexCustomArgs []string
	Task            TaskContextForEnv // context data for writing files
}

// TaskContextForEnv is the subset of task context used for writing context files.
type TaskContextForEnv struct {
	IssueID          string
	TriggerCommentID string // comment that triggered this task (empty for on_assign)
	TriggerThreadID  string // root comment ID for the triggering thread; falls back to TriggerCommentID when empty
	// CommentReplyTargets is set for a comment run that coalesced comments
	// spanning MORE THAN ONE root thread (MUL-4348). When it has >=2 entries the
	// workflow's reply step fans out — one reply per thread — instead of the
	// single --parent=trigger cookbook, keeping this persistent brief in sync
	// with the per-turn prompt so a cross-thread run cannot get one source
	// telling it "one comment" and the other "one per thread". Same-thread
	// follow-ups collapse to a single group upstream, so this stays empty and
	// the single-parent path is used (no duplicate replies).
	CommentReplyTargets []ThreadReplyTarget
	NewCommentCount     int    // issue-wide comments since this agent's last run (excludes its own and the injected trigger)
	NewCommentsSince    string // RFC3339 anchor (last run's started_at) the count is measured from; empty on cold start
	PriorSessionResumed bool   // true when the daemon will resume an existing provider session for this task
	// PriorSessionResumeUnavailable is true when this task carried a prior
	// session the daemon expected to resume but could NOT (the reused workdir was
	// gone, or the Codex rollout was not present in the task CODEX_HOME). The
	// brief surfaces this so the agent tells the user its previous conversation
	// context is gone and this run starts fresh — turning a silent context loss
	// into a user-visible one (MUL-4424). Distinct from an ordinary cold start,
	// which never had a prior session to lose.
	PriorSessionResumeUnavailable bool
	AgentID                       string // unique ID of the dispatched agent
	AgentName                     string
	AgentInstructions             string // agent identity/persona instructions, injected into CLAUDE.md
	AgentSkills                   []SkillContextForEnv
	DisabledRuntimeSkills         []RuntimeSkillRefForEnv
	Repos                         []RepoContextForEnv     // workspace repos available for checkout
	ProjectID                     string                  // active project for this task, when present
	ProjectTitle                  string                  // human-readable project title
	ProjectDescription            string                  // durable project-level context, rendered into the brief's Project Context section
	ProjectResources              []ProjectResourceForEnv // resources attached to the project
	ChatSessionID                 string                  // non-empty for chat tasks
	// ChatChannelType is the IM platform behind a chat session ("slack",
	// "feishu", "wecom"); empty for a web/mobile chat. It names the surface in
	// the brief's copy; what that surface can DELIVER is the separate field
	// below (MUL-4899). The orthogonal audience and history policies live in
	// the per-turn chat prompt (daemon/prompt.go) — the server has no history
	// reader for any other channel.
	ChatChannelType string
	// ChatChannelDeliversFiles is the server's verdict, for THIS turn, on
	// whether a file the agent produces reaches the reader: the adapter goes
	// back for the bound attachment and this deployment has the object storage
	// it goes back to. It arrives on the claim and is used as given. False
	// covers an old server that never sent it, a deployment with no storage,
	// and every channel whose adapter does not perform the hop — all three of
	// which want the same instruction, the one telling the agent to describe
	// its file in words.
	//
	// Carried here but deliberately NOT rendered into the brief. It is a
	// per-turn value: a server upgrade that starts sending it, or object
	// storage being turned on or off, flips it under a chat session that
	// resumes across the change, and the brief is the prompt-cache prefix
	// (MUL-5377). The agent-facing verdict is emitted by the per-turn chat
	// prompt (daemon.buildChatPrompt) instead, and
	// TestBriefByteIdenticalAcrossRunsForEveryKind is what keeps this field out
	// of the brief.
	ChatChannelDeliversFiles bool

	AutopilotRunID          string // non-empty for autopilot run_only tasks
	AutopilotID             string
	AutopilotTitle          string
	AutopilotDescription    string
	AutopilotSource         string
	AutopilotTriggerPayload string
	QuickCreatePrompt       string // non-empty for quick-create tasks
	IsSquadLeader           bool   // true when THIS TASK runs the agent in the squad-leader role (may exit silently on no_action); derived from the claim's is_leader_task / squad_id, never sniffed from instructions text (MUL-5811)
	// WorkspaceContext is the workspace-level system prompt (workspace.context
	// in the DB). Rendered into the brief as `## Workspace Context` when
	// non-empty so every agent in the workspace sees the same shared context,
	// regardless of issue / chat / autopilot / quick-create.
	WorkspaceContext string
	// IssueStatuses is the workspace's active CUSTOM status catalog from the
	// claim payload (MUL-6460), in catalog order. Rendered into the brief's
	// status-command line so agents can see and use statuses beyond the seven
	// built-ins. Like WorkspaceContext, this is durable workspace configuration,
	// not per-turn state: it may legitimately change brief bytes when an admin
	// edits the catalog between runs of a resumed session, exactly as a
	// Workspace Context edit does. Empty — including on old servers that never
	// send the field — renders the built-in-only line byte-identical to before.
	IssueStatuses []IssueStatusForEnv
	// IssueStatusesOmitted is the count of active custom statuses the server's
	// cap dropped from IssueStatuses, so the brief can disclose truncation
	// instead of presenting a partial catalog as complete.
	IssueStatusesOmitted int
	// HasProjectWorkflow is true when the claim carried a project workflow
	// brief for this issue (MUL-7420). The brief then swaps its built-in
	// in_progress / in_review rules for a pointer at that per-turn block, whose
	// statuses and commands are the issue's real contract (MUL-8145). Servers
	// that send no workflow leave it false and the brief unchanged.
	HasProjectWorkflow bool
	// ConnectedApps lists per-run external app capabilities mounted through
	// MCP overlays. Rendered briefly so the agent can map app names such as
	// Notion to the actual MCP server name (`composio`).
	ConnectedApps []runtimeapps.ConnectedApp
	// RequestingUserName + RequestingUserProfileDescription describe the
	// human the agent is acting on behalf of. v1 sources them from the
	// runtime owner (the user who registered the daemon). Rendered into the
	// brief as the `## Requesting User` section only when description is
	// non-empty — empty means the user opted out of injecting profile
	// context and the agent stays anonymous-user mode.
	RequestingUserName               string
	RequestingUserProfileDescription string
	// Initiator* carry the run's authorization human through the existing
	// daemon claim fields. The name and email are per-turn context, not part of
	// the runtime brief. Empty when the run has no originator. See GH-8674.
	InitiatorType  string
	InitiatorID    string
	InitiatorName  string
	InitiatorEmail string
}

// SkillContextForEnv represents a skill to be written into the execution environment.
// IssueStatusForEnv is one active custom workspace status rendered into the
// brief (MUL-6460). Name and Description are user-authored text and MUST pass
// through the brief sanitizers before rendering; Key is constrained by the
// storage CHECK to `^[a-z0-9][a-z0-9_]{0,31}$` but is still guarded with
// sanitizeBriefCodeToken as defense-in-depth.
type IssueStatusForEnv struct {
	Key         string
	Name        string
	Category    string
	Description string
}

type SkillContextForEnv struct {
	Name        string
	Description string
	Content     string
	Files       []SkillFileContextForEnv
}

// SkillFileContextForEnv represents a supporting file within a skill.
type SkillFileContextForEnv struct {
	Path    string
	Content string
}

// Environment represents a prepared, isolated execution environment.
type Environment struct {
	// RootDir is the top-level env directory ({workspacesRoot}/{task_id_short}/).
	RootDir string
	// WorkDir is the directory to pass as Cwd to the agent. Normally
	// ({RootDir}/workdir/); when the task is bound to a local_directory
	// project_resource, it is the user's path instead. See LocalDirectory.
	WorkDir string
	// LocalDirectory is true when WorkDir points at a user-supplied path
	// outside RootDir (the local_directory flow). Callers that key behavior
	// on "may I remove WorkDir as scratch?" must check this — for example
	// the GC loop never deletes the user's directory.
	//
	// Deliberately FALSE in worktree mode: there the workdir is a disposable
	// git worktree inside RootDir, so the env root is ordinary daemon-owned
	// scratch that the GC should reclaim on the normal schedule, and the
	// sidecar rollback that protects a user's directory is unnecessary.
	LocalDirectory bool
	// MulticaConfigRoot is the private per-task config directory exported to
	// child CLI invocations. It prevents implicit discovery of the daemon
	// owner's ~/.multica profile without changing the provider-facing HOME.
	MulticaConfigRoot string
	// LocalWorktree is set when the task runs in worktree mode against a
	// local_directory resource. The daemon calls Finalize on it after the
	// agent exits to commit leftovers, drop the worktree, and learn the
	// branch name to report as the task's result.
	LocalWorktree *LocalWorktree
	// CodexHome is the path to the per-task CODEX_HOME directory (set only for codex provider).
	CodexHome string
	// ClaudeSettingsPath is a task-local --settings JSON file that applies
	// disabled runtime-skill policy without mutating the user's Claude config.
	ClaudeSettingsPath string
	// OpenclawConfigPath is the path to the per-task synthesized OpenClaw
	// config (set only for openclaw provider). The daemon exports this as
	// OPENCLAW_CONFIG_PATH on the openclaw subprocess so its native skill
	// scanner pins workspaceDir to WorkDir.
	OpenclawConfigPath string
	// OpenclawIncludeRoot is the directory of the user's active OpenClaw
	// config (set only for openclaw provider with an on-disk user config).
	// The daemon must prepend it to OPENCLAW_INCLUDE_ROOTS so OpenClaw is
	// allowed to follow the wrapper's `$include` link out of envRoot into
	// the user's config — by default OpenClaw confines `$include` to the
	// directory holding the wrapper file. Empty when no $include is
	// emitted (fresh install).
	OpenclawIncludeRoot string
	// CursorDataDir is the per-task Cursor data directory (set only for
	// cursor provider when the agent has managed mcp_config). The daemon
	// exports this as CURSOR_DATA_DIR so project-level MCP approvals are
	// isolated from the user's persistent ~/.cursor/projects state.
	CursorDataDir string
	// HermesHome is the effective HERMES_HOME overlay (set only for
	// the hermes provider, and only when the agent has skills bound — empty
	// otherwise, leaving the user's real home in place). With a conversation
	// store it lives there; otherwise it lives under the task root. It mirrors ~/.hermes/
	// via symlink, derives a config.yaml that references the user's real skills
	// as an external root, and holds the bound skills in its skills/ subdir. The
	// daemon exports it as HERMES_HOME so the hermes CLI discovers those skills
	// natively — Hermes has no workspace-relative discovery, so the previous
	// .agent_context/skills/ fallback was never read (issue #5242). See
	// hermes_home.go.
	HermesHome string
	// HermesSessionStore is the conversation's durable home, or "" when
	// there is no conversation store and the home stays task-local.
	HermesSessionStore string
	// HermesSessionHistoryPresent reports that the mounted store actually holds
	// a session database — a prior turn's transcript this task can resume.
	// Mounting alone does not imply it: a conversation's first turn, a store the
	// GC reclaimed between turns, a switched Hermes profile and an operator's
	// `rm` all mount cleanly onto nothing. The daemon reads THIS, not the store
	// path, as the answer to "can a prior session id still resolve here?" — see
	// gateResumeToReachableSession.
	HermesSessionHistoryPresent bool
	// QwenpawWorkspace is the path to the per-task QwenPaw workspace directory
	// (set only for the qwenpaw provider). It is populated with the bound skills
	// and their skill.json manifest with enabled: true, so the skills are
	// immediately effective. The daemon passes --workspace <dir> to
	// `qwenpaw acp` so the QwenPaw agent discovers the skills natively.
	// See qwenpaw_workspace.go.
	QwenpawWorkspace string

	logger *slog.Logger // for cleanup logging
	// lockFile holds the env root's exclusive execution lock for as long as
	// this Environment is alive. Released by Cleanup. See claimEnvRoot.
	lockFile *os.File
}

// RootDirParams is the identity and display data used to derive a new task's
// environment root. IDs provide stable collision-safe suffixes; user-controlled
// labels are only readable prefixes and never serve as identity.
type RootDirParams struct {
	WorkspacesRoot  string
	WorkspaceID     string
	WorkspaceSlug   string
	TaskID          string
	IssueIdentifier string
}

// Keep each readable segment within the same aggregate budget as main's
// <workspace UUID>/<12-char task key> layout. The env root prefixes both the
// checkout and git ref paths, so every extra character is costly on Windows.
const readablePathSegmentMax = 24

// PredictRootDir returns the readable path proposed for a task without doing
// I/O. ResolveRootDir freezes the first proposal and must be used by callers
// that need the task's authoritative physical root.
func PredictRootDir(params RootDirParams) string {
	if params.WorkspacesRoot == "" || params.WorkspaceID == "" || params.TaskID == "" {
		return ""
	}
	return filepath.Join(
		params.WorkspacesRoot,
		readablePathSegment(params.WorkspaceSlug, "workspace", params.WorkspaceID),
		readablePathSegment(params.IssueIdentifier, "task", params.TaskID),
	)
}

// readablePathSegment converts a user-controlled label into a bounded,
// lowercase ASCII prefix and appends the stable ID suffix. The suffix keeps
// paths distinct when labels differ only by case, sanitize to the same value,
// or change later.
func readablePathSegment(label, fallback, id string) string {
	prefix := strings.ToLower(strings.TrimSpace(label))
	prefix = nonAlphanumeric.ReplaceAllString(prefix, "-")
	prefix = strings.Trim(prefix, "-")
	if prefix == "" {
		prefix = fallback
	}

	// UUIDv7's leading bits are a timestamp shared by burst-created tasks.
	// taskKey takes the random tail; it is equally suitable for workspace UUIDs.
	suffix := strings.ToLower(taskKey(id))
	maxPrefix := readablePathSegmentMax - len(suffix) - 1
	if len(prefix) > maxPrefix {
		prefix = strings.TrimRight(prefix[:maxPrefix], "-")
	}
	if prefix == "" {
		prefix = fallback
	}
	return prefix + "-" + suffix
}

// Prepare creates an isolated execution environment for a task.
// The workdir starts empty (no repo checkouts). The agent checks out repos
// on demand via `multica repo checkout <url>`.
func Prepare(params PrepareParams, logger *slog.Logger) (*Environment, error) {
	if params.WorkspacesRoot == "" {
		return nil, fmt.Errorf("execenv: workspaces root is required")
	}
	if params.WorkspaceID == "" {
		return nil, fmt.Errorf("execenv: workspace ID is required")
	}
	if params.TaskID == "" {
		return nil, fmt.Errorf("execenv: task ID is required")
	}

	envRoot, err := ResolveRootDir(RootDirParams{
		WorkspacesRoot:  params.WorkspacesRoot,
		WorkspaceID:     params.WorkspaceID,
		WorkspaceSlug:   params.WorkspaceSlug,
		TaskID:          params.TaskID,
		IssueIdentifier: params.IssueIdentifier,
	})
	if err != nil {
		return nil, err
	}

	// Self-heal the root-level daemon marker on every task start so a marker
	// removed while the daemon runs is restored before the agent spawns. The
	// per-workdir marker written below only covers cwds inside the workdir;
	// the root marker keeps the CLI fail-closed guard active for subprocesses
	// that lose all MULTICA_* env vars AND escape above the workdir. Non-fatal:
	// without it the workdir marker still protects the common case.
	if err := EnsureWorkspacesRootMarker(params.WorkspacesRoot); err != nil && logger != nil {
		logger.Warn("execenv: workspaces root marker not written; fail-closed guard limited to the task workdir", "error", err)
	}

	// Take exclusive ownership of the env root before touching anything in it.
	// What follows wipes the directory, and while the segment was a UUIDv7
	// prefix that routinely wiped a live sibling task's workdir, worktree and
	// task-scoped config (#7326). taskKey now reads the id's random tail, which
	// makes a shared path improbable rather than impossible — so prove
	// ownership instead of assuming it. A task that refuses to start is
	// recoverable; one that deletes a running sibling's uncommitted work is not.
	//
	// claimEnvRoot is the only thing standing between two same-key tasks, so it
	// has to be atomic end to end: a read-then-delete would let both pass the
	// check and one still delete the other. Once claimed, the claim is held for
	// the rest of Prepare — the reset below clears the directory's CONTENTS and
	// leaves the marker in place, so there is never a moment where the env root
	// looks unowned to a racing task.
	var lockFile *os.File
	lockClaimed := false
	if params.EnvRootPreclaimed {
		// The caller holds the claim and already reset the root; just make sure
		// the directory is there before populating it.
		if err := os.MkdirAll(envRoot, 0o755); err != nil {
			return nil, fmt.Errorf("execenv: create env root %s: %w", envRoot, err)
		}
	} else {
		lock, reset, err := claimEnvRoot(envRoot, params.WorkspaceID, params.TaskID)
		if err != nil {
			return nil, fmt.Errorf("execenv: %w", err)
		}
		lockFile = lock
		// Release the lock on every failure path below. The successful path
		// hands it to the Environment.
		lockClaimed = true
		defer func() {
			if lockClaimed {
				releaseLockFile(lockFile)
			}
		}()
		// reset means this task already owned the directory and the execution
		// that left it there is gone — a rerun, which is meant to start from a
		// clean tree. Reuse of a PRIOR task's directory never reaches here;
		// that is Reuse, which takes an explicit WorkDir and deletes nothing.
		if reset {
			if err := resetEnvRootContents(envRoot); err != nil {
				return nil, fmt.Errorf("execenv: reset existing env: %w", err)
			}
		}
	}

	// Create directory tree. For the standard flow the agent's workdir is
	// envRoot/workdir; for local_directory tasks the user's path takes its
	// place and we only need to create the scratch directories under
	// envRoot.
	workDir := filepath.Join(envRoot, "workdir")
	scratchDirs := []string{filepath.Join(envRoot, "output"), filepath.Join(envRoot, "logs")}
	if params.LocalWorkDir == "" && params.LocalWorktree == nil {
		scratchDirs = append(scratchDirs, workDir)
	} else if params.LocalWorkDir != "" {
		workDir = params.LocalWorkDir
	}
	for _, dir := range scratchDirs {
		if err := os.MkdirAll(dir, 0o755); err != nil {
			return nil, fmt.Errorf("execenv: create directory %s: %w", dir, err)
		}
	}
	multicaConfigRoot := filepath.Join(envRoot, "multica-config")
	if err := os.MkdirAll(multicaConfigRoot, 0o700); err != nil {
		return nil, fmt.Errorf("execenv: create task-local Multica config directory: %w", err)
	}
	if err := os.Chmod(multicaConfigRoot, 0o700); err != nil {
		return nil, fmt.Errorf("execenv: restrict task-local Multica config directory: %w", err)
	}

	// Worktree mode: build the task's own checkout of the user's repo inside
	// envRoot and use it as the workdir. Done before any context file is
	// written so the sidecars land inside the disposable worktree instead of
	// the user's directory.
	var localWorktree *LocalWorktree
	// Tracks whether Prepare reached its successful return. Everything after
	// worktree creation can still fail — context files, provider homes, MCP
	// config — and on those paths the caller never receives an Environment, so
	// nothing downstream knows a worktree exists to clean up. Without the
	// rollback below, each such failure would leave a registration in the
	// user's repo and a branch that no task ever ran in.
	prepareSucceeded := false
	if params.LocalWorktree != nil {
		wtParams := *params.LocalWorktree
		wtParams.EnvRoot = envRoot
		wtParams.AgentName = params.AgentName
		wtParams.TaskID = params.TaskID
		wtParams.ConversationKey, wtParams.ConversationID = localWorktreeConversation(params)
		wtParams.WorkspaceID = params.WorkspaceID
		wtParams.AgentID = params.Task.AgentID
		var err error
		localWorktree, err = PrepareLocalWorktree(wtParams, logger)
		if err != nil {
			return nil, err
		}
		defer func() {
			if prepareSucceeded {
				return
			}
			// Safe to discard unconditionally: no agent has run yet, so the
			// worktree holds only what Prepare itself put there.
			localWorktree.Discard(logger)
		}()
		workDir = localWorktree.WorkDir
		// The resource may point at a subdirectory that holds only ignored
		// files, in which case git doesn't materialise it in the worktree.
		if err := os.MkdirAll(workDir, 0o755); err != nil {
			return nil, fmt.Errorf("execenv: create worktree workdir %s: %w", workDir, err)
		}
	}

	env := &Environment{
		RootDir:           envRoot,
		WorkDir:           workDir,
		LocalDirectory:    params.LocalWorkDir != "",
		LocalWorktree:     localWorktree,
		MulticaConfigRoot: multicaConfigRoot,
		logger:            logger,
		lockFile:          lockFile,
	}

	// Write context files into workdir (skills go to provider-native paths).
	// Track every file/dir we create in a manifest so CleanupSidecars can
	// roll a local_directory workdir back to its pre-Prepare state. Cloud
	// tasks don't need the manifest (the GC loop wipes envRoot wholesale),
	// but we always write one — it's cheap, keeps Prepare/Reuse symmetric,
	// and avoids a conditional that would silently disable cleanup if the
	// local_directory detection logic ever drifts.
	manifest := &sidecarManifest{}

	// Arm the rollback BEFORE the first write, not after writeContextFiles
	// returns. writeContextFiles puts the daemon task marker down as its very
	// first act and can then fail on any later step — .agent_context, skill
	// files, project resources — so a defer registered after it returns would
	// miss exactly the failures that strand a marker with nothing else around
	// it. Rolling back an empty manifest is a no-op, which is what makes it
	// safe to arm this early.
	//
	// The manifest that records these writes is not persisted until the end of
	// Prepare, and the caller receives no Environment on any failure path, so
	// none of the teardown defers that normally undo this tree are ever
	// registered. Without this rollback the files stay on disk with no record
	// of what to remove (MUL-6132).
	//
	// In place only. Worktree mode discards the whole worktree on failure just
	// above, and a cloud envRoot is wiped wholesale by the GC — only the
	// local_directory flow writes into a directory that outlives the task and
	// belongs to the user, where a leftover marker disables every multica
	// command in that directory tree until someone removes it by hand.
	if params.LocalWorkDir != "" {
		defer func() {
			if prepareSucceeded {
				return
			}
			if err := rollBackPreparedSidecars(*manifest); err != nil && logger != nil {
				logger.Warn("execenv: roll back sidecars after failed prepare", "work_dir", workDir, "error", err)
			}
		}()
	}

	if err := writeContextFiles(workDir, params.Provider, params.Task, manifest); err != nil {
		return nil, fmt.Errorf("execenv: write context files: %w", err)
	}
	if err := prepareOmpMcpConfig(workDir, params.Provider, params.McpConfig, manifest); err != nil {
		return nil, fmt.Errorf("execenv: prepare omp mcp config: %w", err)
	}

	// Persist managed-env provenance for non-local resumable envs at Prepare time
	// (not on completion, where .gc_meta.json is written). A same-issue
	// follow-up can be claimed the instant the prior task completes — before
	// the prior handler writes .gc_meta.json — so reuse eligibility must be
	// provable from an artifact that exists the moment the env is created. Only
	// managed (non-local_directory) issue and chat envs get this marker; that is
	// exactly the set with a durable conversation scope. Non-fatal: a write failure
	// only costs the next follow-up its session reuse (it falls back to a fresh
	// session), which must never block dispatching this task.
	if params.LocalWorkDir == "" && (params.Task.IssueID != "" || params.Task.ChatSessionID != "") {
		if err := WriteManagedEnvProvenance(envRoot, ManagedEnvProvenance{
			WorkspaceID:   params.WorkspaceID,
			IssueID:       params.Task.IssueID,
			ChatSessionID: params.Task.ChatSessionID,
			AgentID:       params.Task.AgentID,
		}); err != nil && logger != nil {
			logger.Warn("execenv: write managed env provenance failed (non-fatal); a follow-up may start a fresh session", "error", err)
		}
	}

	// For Codex, set up a per-task CODEX_HOME seeded from ~/.codex/ with skills.
	if params.Provider == "codex" {
		codexHome := filepath.Join(envRoot, codexHomeDirName)
		if err := prepareCodexHomeWithOpts(codexHome, CodexHomeOptions{CodexVersion: params.CodexVersion, IsLocalDirectory: params.LocalWorkDir != "" || params.LocalWorktree != nil, SessionStoreKey: codexSessionStoreKey(params.Profile, params.Task), CodexCustomArgs: params.CodexCustomArgs}, logger); err != nil {
			return nil, fmt.Errorf("execenv: prepare codex-home: %w", err)
		}
		if err := hydrateCodexSkills(codexHome, params.Task.AgentSkills, params.Task.DisabledRuntimeSkills, logger); err != nil {
			return nil, fmt.Errorf("execenv: hydrate codex skills: %w", err)
		}
		env.CodexHome = codexHome
	}

	if params.Provider == "claude" {
		settingsPath, err := prepareClaudeSkillSettings(envRoot, params.Task.DisabledRuntimeSkills, params.Task.AgentSkills)
		if err != nil {
			return nil, fmt.Errorf("execenv: prepare claude skill settings: %w", err)
		}
		env.ClaudeSettingsPath = settingsPath
	}

	// For Hermes, redirect HERMES_HOME to a per-task compatibility overlay ONLY
	// when the agent has skills bound. A skill-less Hermes task keeps the user's
	// real home and its original behavior untouched. The overlay makes the bound
	// skills visible — Hermes discovers skills only from its home, so the old
	// .agent_context/skills/ fallback was never read (issue #5242). See
	// hermes_home.go.
	//
	// Note this is a local contract, not an observable product behaviour: the
	// server appends the platform's built-in skills to every agent's skill set
	// (service.LoadAgentSkillBundles), so a claimed task's AgentSkills is never
	// empty and the skill-less branch is effectively unreachable in production.
	// Emptying an agent's own skill list is NOT a way to opt out of the overlay.
	if params.Provider == "hermes" && len(params.Task.AgentSkills) > 0 {
		hermesHome := filepath.Join(envRoot, "hermes-home")
		sessions, err := prepareHermesHome(hermesHome, params.HermesSourceHome, params.HermesSourceMustExist, params.Task.AgentSkills, params.HermesEnv, params.HermesMemoryStore, params.HermesSessionStore, logger)
		if err != nil {
			return nil, fmt.Errorf("execenv: prepare hermes-home: %w", err)
		}
		env.HermesHome = sessions.Home
		if sessions.Mounted {
			env.HermesSessionStore = params.HermesSessionStore
			env.HermesSessionHistoryPresent = sessions.HistoryPresent
		}
	}
	if params.Provider == "qwenpaw" {
		qwenpawWorkspace := filepath.Join(envRoot, "qwenpaw-workspace")
		if err := prepareQwenpawWorkspace(qwenpawWorkspace, params.Task.AgentSkills, logger); err != nil {
			return nil, fmt.Errorf("execenv: prepare qwenpaw workspace: %w", err)
		}
		env.QwenpawWorkspace = qwenpawWorkspace
	}

	// For Reasonix, deny the `ask` tool for this task through a project-scoped
	// reasonix.toml. Degraded, not fatal: without it the task still runs under
	// the backend's fail-closed question handling.
	if params.Provider == "reasonix" {
		if err := writeReasonixProjectConfig(workDir, params.ReasonixEnv, manifest, logger); err != nil {
			logger.Warn("execenv: write reasonix project config failed", "error", err)
		}
	}

	// For Cursor, materialize managed MCP into project-local config and use
	// an isolated CURSOR_DATA_DIR for the per-workdir approval sidecar. Cursor
	// still reads ~/.cursor/mcp.json, but only servers with approval entries in
	// this per-task data dir can load, so user-global MCP servers do not leak
	// into managed-MCP runs.
	if params.Provider == "cursor" {
		cursorDataDir, err := prepareCursorMcpConfig(envRoot, workDir, params.McpConfig, params.CursorMcpAuthSource, manifest)
		if err != nil {
			return nil, fmt.Errorf("execenv: prepare cursor mcp config: %w", err)
		}
		env.CursorDataDir = cursorDataDir
	}

	if err := writeSidecarManifest(envRoot, manifest); err != nil {
		// In place the manifest is the ONLY record of what we wrote into the
		// user's own directory, so losing it strands the sidecar tree there
		// permanently — no crash required, a disk or permission hiccup is
		// enough (MUL-6132). Fail so the rollback registered above removes the
		// tree now, while we still hold the in-memory manifest. Elsewhere the
		// manifest is a convenience the GC can do without, so a warning stays
		// the right response.
		if params.LocalWorkDir != "" {
			return nil, fmt.Errorf("execenv: write sidecar manifest: %w", err)
		}
		logger.Warn("execenv: write sidecar manifest failed (non-fatal)", "error", err)
	}

	// For OpenClaw, synthesize a per-task config that pins workspace to
	// workDir. The skill scanner then reads {workDir}/skills/ (written by
	// writeContextFiles above). Fail closed on errors: a malformed user
	// config that the openclaw CLI can't read is a real problem and
	// silently degrading to a minimal config would mask it by booting
	// OpenClaw without the agents / providers / API keys it expects.
	if params.Provider == "openclaw" {
		result, err := prepareOpenclawConfig(envRoot, workDir, OpenclawConfigPrep{
			OpenclawBin: params.OpenclawBin,
			CacheDir:    openclawProfileCacheDir(params.Profile, logger),
			McpConfig:   params.McpConfig,
			Gateway:     params.OpenclawGateway,
			Logger:      logger,
		})
		if err != nil {
			return nil, fmt.Errorf("execenv: prepare openclaw config: %w", err)
		}
		env.OpenclawConfigPath = result.ConfigPath
		env.OpenclawIncludeRoot = result.IncludeRoot
	}

	logger.Info("execenv: prepared env", "root", envRoot, "repos_available", len(params.Task.Repos))
	prepareSucceeded = true
	lockClaimed = false // ownership of any lock passes to the Environment
	return env, nil
}

// ReuseParams describes the inputs to Reuse. It mirrors PrepareParams for
// the per-provider knobs (CodexVersion, OpenclawBin) so callers can pass
// the same resolved binary path on both first-run and reuse paths.
type ReuseParams struct {
	// WorkspacesRoot is the daemon-owned root under which all task envs live.
	// Passed on reuse so the root-level fail-closed marker is self-healed here
	// too — a marker removed while the daemon runs is restored before a reused
	// task spawns, not only on the fresh-Prepare path.
	WorkspacesRoot string
	WorkDir        string
	Provider       string
	CodexVersion   string // only used when Provider == "codex"
	// ResumeSessionID is the prior Codex thread/session ID this reused task
	// intends to resume, when any. Only consulted when Provider == "codex" and
	// only used while migrating a legacy per-task home whose sessions/ still
	// symlinks the shared ~/.codex/sessions — the single rollout for this ID is
	// exposed into the new task-local sessions dir so thread/resume still finds
	// it. Empty means a fresh thread. See prepareCodexSessionsDir (MUL-4424).
	ResumeSessionID string
	OpenclawBin     string // only used when Provider == "openclaw"; empty = PATH lookup
	// McpConfig is the agent's saved `mcp_config` JSON. Reused on reuse so a
	// freshly-saved managed set re-materialises into the wrapper before the
	// task starts — without this a stale wrapper from a prior run would keep
	// the old MCP set in play.
	McpConfig json.RawMessage
	// CursorMcpAuthSource mirrors PrepareParams.CursorMcpAuthSource on reuse.
	CursorMcpAuthSource string
	// OpenclawGateway is the per-task Gateway pin re-applied on reuse so the
	// agent picks up any runtime_config changes saved since the prior run.
	OpenclawGateway OpenclawGatewayPin
	// Profile is the daemon's profile name (empty = default), mirroring
	// PrepareParams.Profile so a reused task keys its per-issue Codex session
	// store into the same profile namespace (MUL-4424).
	Profile string
	// LocalDirectory is true when the reused WorkDir is a user-supplied
	// directory (the local_directory flow). The flag is propagated into
	// the returned Environment so downstream callers (notably the GC
	// loop) keep the "never delete the user's directory" invariant on
	// reuse paths.
	LocalDirectory bool
	// HermesSourceHome, HermesEnv, HermesMemoryStore and HermesSessionStore
	// mirror PrepareParams on reuse so the Hermes overlay re-derives against the
	// agent's current source home / profile, external_dirs vars, memory store and
	// conversation session store.
	HermesSourceHome      string
	HermesSourceMustExist bool
	HermesEnv             map[string]string
	HermesMemoryStore     string
	HermesSessionStore    string
	// ReasonixEnv mirrors PrepareParams.ReasonixEnv on reuse so the rewritten
	// reasonix.toml keeps restating the owner's current permissions.
	ReasonixEnv map[string]string
	// CodexCustomArgs mirrors PrepareParams.CodexCustomArgs on reuse so the
	// Windows sandbox decision honors a `-c windows.sandbox=...` override here
	// too (MUL-4957).
	CodexCustomArgs []string
	Task            TaskContextForEnv // refreshed context files / skills
}

// Reuse wraps an existing workdir into an Environment and refreshes context files.
// Returns nil if the workdir does not exist or required provider setup fails
// (caller should fall back to Prepare).
func Reuse(params ReuseParams, logger *slog.Logger) *Environment {
	if _, err := os.Stat(params.WorkDir); err != nil {
		return nil
	}

	// Self-heal the root-level daemon marker on the reuse path too, so a marker
	// removed while the daemon runs is restored before a reused task spawns —
	// otherwise reuse could run without the fail-closed guard until the next
	// fresh Prepare. Non-fatal: the per-workdir marker still protects the common
	// case, and an empty WorkspacesRoot (legacy callers) simply skips this.
	if params.WorkspacesRoot != "" {
		if err := EnsureWorkspacesRootMarker(params.WorkspacesRoot); err != nil && logger != nil {
			logger.Warn("execenv: workspaces root marker not written on reuse; fail-closed guard limited to the task workdir", "error", err)
		}
	}

	rootDir := filepath.Dir(params.WorkDir)
	if params.LocalDirectory {
		// For local_directory tasks the user's WorkDir is unrelated to
		// envRoot (envRoot still lives under workspacesRoot/{wsID}/...),
		// so reading it from filepath.Dir(WorkDir) would point at the
		// parent of the user's directory. Callers that need a real
		// RootDir on the reuse path should arrange to pass it in
		// explicitly; for v1 the daemon only ever reuses local_directory
		// workdirs after a fresh Prepare in the same task lifetime, so
		// the empty RootDir on reuse is fine for the current callers
		// (GC writes meta from Prepare's result, not Reuse's).
		rootDir = ""
	}
	env := &Environment{
		RootDir:        rootDir,
		WorkDir:        params.WorkDir,
		LocalDirectory: params.LocalDirectory,
		logger:         logger,
	}
	if env.RootDir != "" {
		env.MulticaConfigRoot = filepath.Join(env.RootDir, "multica-config")
		if err := os.MkdirAll(env.MulticaConfigRoot, 0o700); err != nil {
			logger.Warn("execenv: restore task-local Multica config directory failed; forcing fresh prepare", "error", err)
			return nil
		}
		if err := os.Chmod(env.MulticaConfigRoot, 0o700); err != nil {
			logger.Warn("execenv: restrict task-local Multica config directory failed; forcing fresh prepare", "error", err)
			return nil
		}
	}

	// Roll back the previous dispatch's sidecar writes before refreshing.
	// On reuse the workdir still holds the prior run's skill directories (and,
	// for a workdir prepared before MUL-6984, its issue_context.md); without
	// clearing them first, writeSkillFiles sees
	// its own earlier output occupying the canonical slug and falls back to
	// a collision-free sibling (issue-review, issue-review-multica,
	// issue-review-multica-2, …), accumulating a fresh duplicate on every
	// re-dispatch to the same issue. allocateCollisionFreeSkillDir exists to
	// dodge *user*-owned skill dirs (the local_directory flow), not our own
	// prior writes, so we undo them via the prior manifest first and let the
	// refresh below re-create each skill at its natural slug. This also brings
	// the standard providers in line with the Codex path, where
	// hydrateCodexSkills already wipes its skills dir before re-hydrating.
	//
	// Two steps, in order:
	//   1. removeReusedManagedSkillDirs reclaims the platform's own skill
	//      directories even when a prior-run agent left a file inside one.
	//      CleanupSidecars alone can't do this — it preserves any recorded dir
	//      the agent populated (correct on the local_directory teardown path),
	//      which would otherwise keep the canonical slug occupied and push the
	//      refresh back to issue-review-multica.
	//   2. CleanupSidecars rolls back the remaining sidecar files (project
	//      resources today, plus any issue_context.md recorded by a manifest
	//      an older build wrote — legacy upgrade cleanup, not a live writer)
	//      and the manifest itself.
	//
	// No-op when RootDir is empty (legacy local_directory reuse, which the
	// daemon skips anyway) or when no prior manifest exists (older build).
	if env.RootDir != "" {
		if err := removeReusedManagedSkillDirs(env.RootDir, skillsDirPath(params.WorkDir, params.Provider)); err != nil {
			logger.Warn("execenv: reclaim managed skill dirs on reuse failed", "error", err)
		}
		if err := CleanupSidecars(env.RootDir); err != nil {
			logger.Warn("execenv: roll back prior sidecars on reuse failed", "error", err)
		}
	}

	// Refresh context files (skills, project resources). Reuse tracks a
	// fresh manifest under env.RootDir so a later CleanupSidecars sees
	// the up-to-date list of writes (an old manifest from a prior run
	// would otherwise reference files this Reuse no longer creates). For
	// local_directory tasks the daemon skips Reuse entirely (see
	// daemon.runTask), but writing the manifest unconditionally keeps
	// Prepare/Reuse symmetric so a future caller can rely on the
	// manifest being current after either path. RootDir is empty on the
	// legacy local_directory Reuse fallback — skip the persist in that
	// case to avoid creating a stray manifest at the filesystem root.
	manifest := &sidecarManifest{}
	if err := writeContextFiles(params.WorkDir, params.Provider, params.Task, manifest); err != nil {
		logger.Warn("execenv: refresh context files failed", "error", err)
	}
	if err := prepareOmpMcpConfig(params.WorkDir, params.Provider, params.McpConfig, manifest); err != nil {
		logger.Warn("execenv: refresh omp mcp config failed; forcing fresh prepare", "error", err)
		return nil
	}

	// Restore CodexHome for Codex provider — the per-task codex-home directory
	// lives alongside the workdir. Re-run prepareCodexHomeWithOpts to ensure
	// config (especially sandbox/network access) is up to date.
	if params.Provider == "codex" {
		codexHome := filepath.Join(env.RootDir, codexHomeDirName)
		if err := prepareCodexHomeWithOpts(codexHome, CodexHomeOptions{CodexVersion: params.CodexVersion, ResumeSessionID: params.ResumeSessionID, IsLocalDirectory: params.LocalDirectory, SessionStoreKey: codexSessionStoreKey(params.Profile, params.Task), CodexCustomArgs: params.CodexCustomArgs}, logger); err != nil {
			// Leaving env.CodexHome empty does not launch Codex against an
			// ambient home: configureCodexTaskShellEnvironment rejects the empty
			// value ("task CODEX_HOME is missing") and the run fails before
			// launch. Decline the reuse instead, so the caller falls back to
			// Prepare and the task still gets a usable task-local home. The
			// prior session is not carried over, and a fresh Prepare that fails
			// the same way still stops the task.
			logger.Warn("execenv: refresh codex-home failed; forcing fresh prepare", "error", err)
			return nil
		} else {
			env.CodexHome = codexHome
			if err := hydrateCodexSkills(codexHome, params.Task.AgentSkills, params.Task.DisabledRuntimeSkills, logger); err != nil {
				logger.Warn("execenv: refresh codex skills failed", "error", err)
			}
		}
	}

	if params.Provider == "claude" && env.RootDir != "" {
		settingsPath, err := prepareClaudeSkillSettings(env.RootDir, params.Task.DisabledRuntimeSkills, params.Task.AgentSkills)
		if err != nil {
			logger.Warn("execenv: refresh claude skill settings failed", "error", err)
		} else {
			env.ClaudeSettingsPath = settingsPath
		}
	}

	// Re-deny Reasonix's `ask` tool on reuse: CleanupSidecars above removed the
	// prior run's reasonix.toml, so without this the next turn would run with
	// the tool available again.
	if params.Provider == "reasonix" {
		if err := writeReasonixProjectConfig(params.WorkDir, params.ReasonixEnv, manifest, logger); err != nil {
			logger.Warn("execenv: refresh reasonix project config failed", "error", err)
		}
	}

	// Refresh (or tear down) the per-task QwenPaw workspace on reuse.
	// Rebuild the workspace so an added/removed/edited skill is reflected.
	if params.Provider == "qwenpaw" && env.RootDir != "" {
		qwenpawWorkspace := filepath.Join(env.RootDir, "qwenpaw-workspace")
		if err := prepareQwenpawWorkspace(qwenpawWorkspace, params.Task.AgentSkills, logger); err != nil {
			logger.Warn("execenv: refresh qwenpaw workspace failed; forcing fresh prepare", "error", err)
			return nil
		}
		env.QwenpawWorkspace = qwenpawWorkspace
	}

	// Refresh (or tear down) the per-task HERMES_HOME on reuse. With skills
	// bound, rebuild the overlay so an added/removed/edited skill and the
	// mirrored home/config track the user's current ~/.hermes/ before the next
	// hermes process starts. With no skills bound, drop the redirect entirely so
	// the task reverts to the user's real home — matching a fresh Prepare for a
	// skill-less agent.
	if params.Provider == "hermes" && env.RootDir != "" {
		hermesHome := filepath.Join(env.RootDir, "hermes-home")
		if len(params.Task.AgentSkills) > 0 {
			sessions, err := prepareHermesHome(hermesHome, params.HermesSourceHome, params.HermesSourceMustExist, params.Task.AgentSkills, params.HermesEnv, params.HermesMemoryStore, params.HermesSessionStore, logger)
			if err != nil {
				// Fail closed: a half-built overlay must not run. Returning nil
				// makes the daemon fall back to a fresh Prepare, whose error
				// then blocks dispatch rather than silently dropping the bound
				// skill.
				logger.Warn("execenv: refresh hermes-home failed; forcing fresh prepare", "error", err)
				return nil
			}
			env.HermesHome = sessions.Home
			env.HermesSessionStore = ""
			env.HermesSessionHistoryPresent = false
			if sessions.Mounted {
				env.HermesSessionStore = params.HermesSessionStore
				env.HermesSessionHistoryPresent = sessions.HistoryPresent
			}
		} else {
			env.HermesHome = ""
			env.HermesSessionStore = ""
			env.HermesSessionHistoryPresent = false
			if err := os.RemoveAll(hermesHome); err != nil {
				logger.Warn("execenv: remove stale hermes-home failed", "error", err)
			}
		}
	}

	// Refresh Cursor's managed MCP sidecars on reuse. A newly saved agent
	// mcp_config must replace the prior run's .cursor/mcp.json and isolated
	// approvals before the next cursor-agent process starts.
	if params.Provider == "cursor" && env.RootDir != "" {
		cursorDataDir, err := prepareCursorMcpConfig(env.RootDir, params.WorkDir, params.McpConfig, params.CursorMcpAuthSource, manifest)
		if err != nil {
			logger.Warn("execenv: refresh cursor mcp config failed", "error", err)
			return nil
		}
		env.CursorDataDir = cursorDataDir
	}

	if env.RootDir != "" {
		if err := writeSidecarManifest(env.RootDir, manifest); err != nil {
			logger.Warn("execenv: refresh sidecar manifest failed", "error", err)
		}
	}

	// Refresh the per-task OpenClaw config on reuse — the user may have
	// added/removed agents or rotated providers since the prior task ran,
	// and the workspace override always re-targets the current workDir.
	// Fail closed: a user config that can no longer be parsed should block
	// reuse rather than degrade to a minimal config that boots OpenClaw
	// without the registered agents.
	if params.Provider == "openclaw" {
		result, err := prepareOpenclawConfig(env.RootDir, params.WorkDir, OpenclawConfigPrep{
			OpenclawBin: params.OpenclawBin,
			CacheDir:    openclawProfileCacheDir(params.Profile, logger),
			McpConfig:   params.McpConfig,
			Gateway:     params.OpenclawGateway,
			Logger:      logger,
		})
		if err != nil {
			logger.Warn("execenv: refresh openclaw config failed", "error", err)
			return nil
		}
		env.OpenclawConfigPath = result.ConfigPath
		env.OpenclawIncludeRoot = result.IncludeRoot
	}

	logger.Info("execenv: reusing env", "workdir", params.WorkDir)
	return env
}

// hydrateCodexSkills populates the per-task CODEX_HOME/skills directory with
// both user-installed skills (from the shared ~/.codex/skills/) and
// workspace-assigned skills. Workspace skills win on name conflict — they are
// written last and seedUserCodexSkills already pre-filters their names.
//
// The skills directory is wiped first so two stale-state classes that the
// Reuse path would otherwise leak are gone:
//
//   - A name now claimed by a workspace skill that previously held only a
//     user-seeded copy — support files from the user version would otherwise
//     linger under the workspace skill's directory.
//   - A user skill removed from the shared ~/.codex/skills/ since the last
//     run — its old contents would otherwise remain visible to the codex
//     CLI.
//
// Codex is the only runtime that needs this two-stage hydration because the
// daemon sets CODEX_HOME to a per-task directory, isolating the CLI from the
// user's real ~/.codex/. Other runtimes leave HOME untouched and discover
// user-level skills natively (see context.go for the workdir-local paths
// they use for workspace skills).
func hydrateCodexSkills(codexHome string, workspaceSkills []SkillContextForEnv, disabledRuntimeSkills []RuntimeSkillRefForEnv, logger *slog.Logger) error {
	skillsDir := filepath.Join(codexHome, "skills")
	if err := os.RemoveAll(skillsDir); err != nil {
		return fmt.Errorf("clear codex skills dir: %w", err)
	}
	if err := seedUserCodexSkills(codexHome, workspaceSkills, logger); err != nil {
		logger.Warn("execenv: seed user codex skills failed", "error", err)
	}
	if len(workspaceSkills) > 0 {
		if err := writeSkillFiles(skillsDir, workspaceSkills, nil); err != nil {
			return err
		}
	}
	return ensureCodexDisabledSkillsConfig(filepath.Join(codexHome, "config.toml"), codexHome, disabledRuntimeSkills, workspaceSkills)
}

// GCMetaKind identifies which kind of parent record a task workdir belongs to.
// The GC loop dispatches its decision tree on this value so chat / autopilot /
// quick-create tasks are no longer forced through the issue-centric path.
type GCMetaKind string

const (
	GCKindIssue        GCMetaKind = "issue"
	GCKindChat         GCMetaKind = "chat"
	GCKindAutopilotRun GCMetaKind = "autopilot_run"
	GCKindQuickCreate  GCMetaKind = "quick_create"
)

// GCMeta is persisted to .gc_meta.json inside the env root so the GC loop
// can decide whether the directory is reclaimable. It is a discriminated
// union keyed on Kind: only the parent ID field matching Kind is meaningful.
// TaskID is also persisted for every new task so local reports never need to
// recover task identity from the directory name; for quick-create it doubles
// as the parent ID used by the GC status endpoint.
//
// Older meta files (pre-v2) lack the Kind field; readers must default empty
// Kind to GCKindIssue for backward compatibility — only IssueID was written
// before, and only issue-centric tasks ever produced a meta file.
type GCMeta struct {
	Kind           GCMetaKind `json:"kind,omitempty"`
	IssueID        string     `json:"issue_id,omitempty"`
	ChatSessionID  string     `json:"chat_session_id,omitempty"`
	AutopilotRunID string     `json:"autopilot_run_id,omitempty"`
	TaskID         string     `json:"task_id,omitempty"`
	WorkspaceID    string     `json:"workspace_id"`
	CompletedAt    time.Time  `json:"completed_at"`
	// LocalDirectory marks tasks whose WorkDir pointed at a user-owned
	// path rather than the synthesised envRoot/workdir. The GC loop honours
	// this by never falling into the gcActionClean branch (which would
	// RemoveAll envRoot — safe by structure, but we still want to keep the
	// envRoot's output/ and logs/ around longer so users can inspect what
	// the agent did in their own tree). Pattern-based artifact cleanup is
	// still allowed.
	LocalDirectory bool `json:"local_directory,omitempty"`
}

const gcMetaFile = ".gc_meta.json"

// WriteGCMeta writes GC metadata into the given directory. The caller is
// responsible for choosing Kind and populating the matching ID field;
// CompletedAt is stamped here so callers don't have to think about clocks.
func WriteGCMeta(envRoot string, meta GCMeta, logger *slog.Logger) error {
	if envRoot == "" {
		return nil
	}
	if meta.Kind == "" {
		// Defensive: a task that doesn't fit any known kind would write a
		// meta file the GC loop can't dispatch on. Skip silently — the
		// directory falls back to the orphan-by-mtime path.
		logger.Debug("execenv: skipping .gc_meta.json write: kind is empty", "envRoot", envRoot)
		return nil
	}
	meta.CompletedAt = time.Now().UTC()
	data, err := json.Marshal(meta)
	if err != nil {
		return fmt.Errorf("marshal gc meta: %w", err)
	}
	return os.WriteFile(filepath.Join(envRoot, gcMetaFile), data, 0o644)
}

// ReadGCMeta reads GC metadata from a task directory root. Pre-v2 meta files
// (no kind field) are normalized to GCKindIssue so the legacy issue path
// keeps working without a migration.
func ReadGCMeta(envRoot string) (*GCMeta, error) {
	data, err := os.ReadFile(filepath.Join(envRoot, gcMetaFile))
	if err != nil {
		return nil, err
	}
	var meta GCMeta
	if err := json.Unmarshal(data, &meta); err != nil {
		return nil, err
	}
	if meta.Kind == "" {
		meta.Kind = GCKindIssue
	}
	return &meta, nil
}

const managedEnvProvenanceFile = ".managed_env.json"

// ManagedEnvProvenanceManagedBy discriminates a managed-env provenance file
// the daemon wrote from any lookalike JSON that happens to share the path.
const ManagedEnvProvenanceManagedBy = "multica-daemon-managed-env"

// ManagedEnvProvenance is persisted to .managed_env.json inside the env root at
// Prepare time (NOT on completion, unlike .gc_meta.json). It records that this
// env root is a daemon-managed, non-local_directory resumable env owned by a
// specific workspace, conversation scope, and agent.
//
// Its whole reason to exist is timing. A squad-leader follow-up on the same
// issue can be claimed the instant the prior task completes — the server's
// task-complete handler reconciles the follow-up and wakes the runtime before
// the prior task's daemon handler writes .gc_meta.json. Keying reuse
// eligibility off .gc_meta.json therefore raced: the successor read a
// not-yet-written file and started a fresh session (MUL-4886). This marker is
// on disk from the moment the env is created, so the successor can prove reuse
// safety inside that window. It is written only for non-local managed issue or
// chat envs, so its presence is itself the "safe to reuse, not a user
// local_directory" assertion; see shouldReusePriorWorkdir.
type ManagedEnvProvenance struct {
	ManagedBy     string `json:"managed_by"`
	WorkspaceID   string `json:"workspace_id"`
	IssueID       string `json:"issue_id,omitempty"`
	ChatSessionID string `json:"chat_session_id,omitempty"`
	AgentID       string `json:"agent_id"`
}

// WriteManagedEnvProvenance persists the reuse-eligibility marker at the env
// root. Callers must only invoke it for non-local_directory resumable envs, since
// the file's presence is the non-local assertion. ManagedBy is stamped here so
// callers cannot forget the discriminator.
func WriteManagedEnvProvenance(envRoot string, p ManagedEnvProvenance) error {
	if envRoot == "" {
		return nil
	}
	p.ManagedBy = ManagedEnvProvenanceManagedBy
	data, err := json.Marshal(p)
	if err != nil {
		return fmt.Errorf("marshal managed env provenance: %w", err)
	}
	return os.WriteFile(filepath.Join(envRoot, managedEnvProvenanceFile), data, 0o644)
}

// ReadManagedEnvProvenance reads the Prepare-time reuse-eligibility marker from
// an env root. A missing or malformed file returns an error; callers fail
// closed (no reuse) on any error.
func ReadManagedEnvProvenance(envRoot string) (*ManagedEnvProvenance, error) {
	data, err := os.ReadFile(filepath.Join(envRoot, managedEnvProvenanceFile))
	if err != nil {
		return nil, err
	}
	var p ManagedEnvProvenance
	if err := json.Unmarshal(data, &p); err != nil {
		return nil, err
	}
	return &p, nil
}

// Cleanup tears down the execution environment.
// If removeAll is true, the entire env root is deleted. Otherwise, workdir is
// removed but output/ and logs/ are preserved for debugging.
//
// For local_directory tasks (env.LocalDirectory==true) WorkDir is the
// user's own path — Cleanup MUST NEVER delete it, regardless of removeAll.
// In that mode we only ever delete the envRoot scratch directory.
func (env *Environment) Cleanup(removeAll bool) error {
	if env == nil {
		return nil
	}
	// Drop the execution lock first. Until it is released the env root still
	// reads as "a live execution owns this", which would make a legitimate
	// rerun fail closed. The daemon also defers ReleaseLock for the task run;
	// both paths are idempotent.
	env.ReleaseLock()

	if env.LocalDirectory {
		// Never touch the user's directory. RootDir is the daemon's own
		// scratch; safe to remove when the caller asked for a full
		// teardown.
		if removeAll && env.RootDir != "" {
			if err := os.RemoveAll(env.RootDir); err != nil {
				env.logger.Warn("execenv: cleanup local_directory envRoot failed", "error", err)
				return err
			}
		}
		return nil
	}

	if removeAll {
		if err := os.RemoveAll(env.RootDir); err != nil {
			env.logger.Warn("execenv: cleanup removeAll failed", "error", err)
			return err
		}
		return nil
	}

	// Partial cleanup: remove workdir, keep output/ and logs/.
	if err := os.RemoveAll(env.WorkDir); err != nil {
		env.logger.Warn("execenv: cleanup workdir failed", "error", err)
		return err
	}
	return nil
}

// EnvRootClaim is a held claim on a task's env root. It exists so the claim can
// outlive the code that prepares the directory.
//
// Production preparation runs in a short-lived helper process
// (PrepareIsolated / ReuseIsolated). A lock taken inside that helper is
// released by the kernel as soon as it exits, and *os.File cannot travel back
// through the helper's JSON response — so a claim taken there protects
// nothing by the time the agent actually runs. The daemon parent takes the
// claim instead and holds it for the whole task run.
type EnvRootClaim struct {
	rootDir string
	lock    *os.File
}

// RootDir is the env root this claim covers.
func (c *EnvRootClaim) RootDir() string {
	if c == nil {
		return ""
	}
	return c.rootDir
}

// Release drops the claim. Safe on nil and safe to call twice.
func (c *EnvRootClaim) Release() {
	if c == nil || c.lock == nil {
		return
	}
	releaseLockFile(c.lock)
	c.lock = nil
}

// ClaimEnvRoot takes the full claim for a fresh preparation of taskID: it
// proves ownership, refuses a root a live execution or another task holds, and
// resets a stale root this task owns so the caller receives a clean directory.
//
// Callers that pass the claim to Prepare must also set
// PrepareParams.EnvRootPreclaimed, or Prepare will try to take a lock this
// claim already holds and fail.
func ClaimEnvRoot(params RootDirParams) (*EnvRootClaim, error) {
	envRoot, err := ResolveRootDir(params)
	if err != nil {
		return nil, fmt.Errorf("execenv: resolve env root: %w", err)
	}
	if envRoot == "" {
		return nil, fmt.Errorf("execenv: claim env root: workspaces root, workspace ID and task ID are all required")
	}
	lock, reset, err := claimEnvRoot(envRoot, params.WorkspaceID, params.TaskID)
	if err != nil {
		return nil, fmt.Errorf("execenv: %w", err)
	}
	if reset {
		if err := resetEnvRootContents(envRoot); err != nil {
			releaseLockFile(lock)
			return nil, fmt.Errorf("execenv: reset existing env: %w", err)
		}
	}
	return &EnvRootClaim{rootDir: envRoot, lock: lock}, nil
}

// ErrEnvRootBusy reports that a live execution already holds an env root. On
// the reuse path it is a reason to fall back to a fresh Prepare, not to fail
// the task.
var ErrEnvRootBusy = errors.New("env root is held by a running execution")

// LockEnvRootForReuse takes the exclusion half of a claim, without the identity
// half, for a task continuing in a PRIOR task's directory.
//
// Reuse adopts another task's env root on purpose, so the owner marker names
// that earlier task and must not be reinterpreted or overwritten — but two
// continuations of the same task still must not refresh and run the same
// directory at once.
//
// wsRoot must be a Root the CALLER opened before it validated anything, and
// rel the env root's path within it. Both matter:
//
//   - Opening the Root here, from a name the caller validated a moment ago,
//     would re-resolve that name. Renaming the whole workspaces root aside and
//     leaving a symlink to a look-alike tree in its place would have os.Root
//     faithfully pin the replacement — Root guarantees you cannot escape the
//     tree it opened, not that it opened the tree you meant.
//   - Every operation below goes through ONE sub-Root pinned on the env root,
//     so the directory whose identity is returned and the directory the lock
//     file is created in cannot be two different directories. Resolving rel
//     twice from wsRoot would allow exactly that: A on the first resolution,
//     B on the second.
//
// It returns that directory's FileInfo so the caller can confirm it is the one
// validation approved; Root still follows symlinks that stay inside the tree,
// so "locked A, reused B" has to be ruled out by identity, not containment.
//
// Returns a nil claim and no error when the env root is missing, and
// ErrEnvRootBusy when another execution holds it — both mean "fall back to a
// fresh Prepare".
func LockEnvRootForReuse(wsRoot *os.Root, rel, envRoot string) (*EnvRootClaim, os.FileInfo, error) {
	if wsRoot == nil || rel == "" || !filepath.IsLocal(rel) {
		return nil, nil, fmt.Errorf("execenv: env root %s is not inside the workspaces root", envRoot)
	}

	// Pin the env root itself. From here on nothing is resolved by name again.
	envRootHandle, err := wsRoot.OpenRoot(rel)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return nil, nil, nil
		}
		return nil, nil, fmt.Errorf("execenv: open env root %s: %w", envRoot, err)
	}
	defer envRootHandle.Close()

	info, err := envRootHandle.Stat(".")
	if err != nil {
		return nil, nil, fmt.Errorf("execenv: inspect env root %s: %w", envRoot, err)
	}
	if !info.IsDir() {
		return nil, nil, nil
	}

	lock, err := envRootHandle.OpenFile(envRootLockFile, os.O_CREATE|os.O_RDWR, 0o644)
	if err != nil {
		return nil, nil, fmt.Errorf("execenv: open env root lock for %s: %w", envRoot, err)
	}
	locked, err := lockFileExclusiveNonBlocking(lock)
	if err != nil {
		lock.Close()
		return nil, nil, fmt.Errorf("execenv: lock env root %s: %w", envRoot, err)
	}
	if !locked {
		lock.Close()
		return nil, nil, fmt.Errorf("execenv: reuse %s: %w", envRoot, ErrEnvRootBusy)
	}
	return &EnvRootClaim{rootDir: envRoot, lock: lock}, info, nil
}

// envRootOwnerFile records which workspace and task an env root belongs to:
// WHO owns it. The execution lock below separately answers whether that owner
// is still running.
const envRootOwnerFile = ".task_owner"

const (
	envRootOwnerTempPrefix = ".task_owner-"
	envRootOwnerTempSuffix = ".tmp"
)

// envRootLockFile carries the env root's exclusive execution lock: whether the
// owner is STILL RUNNING. The two answer different questions and both are
// needed — a dead task's directory still holds its work, and a live task's
// directory must not be reset even by another execution of the same task.
const envRootLockFile = ".task_lock"

// claimEnvRoot takes exclusive ownership of envRoot for taskID.
//
// It returns the held lock file — the caller owns it until Cleanup — and
// whether the directory needs resetting before use.
//
// The lock is an OS advisory lock, and the kernel releases it when the holding
// process exits for any reason. That is what makes it a lock rather than a
// third marker file: it answers "is the previous execution still alive?"
// across processes, with no heartbeat, no PID table and no stale-state cleanup
// path. An identity marker alone cannot answer it, which is how the previous
// design let a re-dispatched execution of the SAME task id wipe the directory
// of an execution that was still running (#7326 follow-up):
//
//   - The server re-delivers a task row whose prepare lease expired
//     (ReclaimStaleDispatchedTaskForRuntime) using the same task id.
//   - A failing lease renewal only logs; it does not cancel the Prepare that
//     is still in flight.
//   - So two Prepare calls for one task id could overlap, and "owner == mine"
//     read as "my own rerun, safe to reset".
//
// Holding the lock also serialises everything below it, which is what makes
// repairing a torn marker safe: no other execution can be mid-claim.
func claimEnvRoot(envRoot, workspaceID, taskID string) (lockFile *os.File, reset bool, err error) {
	if err := os.MkdirAll(envRoot, 0o755); err != nil {
		return nil, false, fmt.Errorf("create env root %s: %w", envRoot, err)
	}

	lockFile, err = openLockFile(filepath.Join(envRoot, envRootLockFile))
	if err != nil {
		return nil, false, fmt.Errorf("open env root lock for %s: %w", envRoot, err)
	}
	locked, err := lockFileExclusiveNonBlocking(lockFile)
	if err != nil {
		lockFile.Close()
		return nil, false, fmt.Errorf("lock env root %s: %w", envRoot, err)
	}
	if !locked {
		lockFile.Close()
		return nil, false, fmt.Errorf("env root %s is held by a running execution; refusing to reset it for task %s", envRoot, taskID)
	}
	// Past this point we are the only execution touching this env root, in this
	// process or any other, so the checks below cannot race.
	defer func() {
		if err != nil {
			releaseLockFile(lockFile)
			lockFile = nil
		}
	}()
	if err := removeStaleEnvRootOwnerTemps(envRoot); err != nil {
		return nil, false, fmt.Errorf("remove stale env root owner temp files for %s: %w", envRoot, err)
	}

	owner, err := ReadEnvRootOwner(envRoot)
	if err != nil {
		return nil, false, fmt.Errorf("read env root owner for %s: %w", envRoot, err)
	}
	switch {
	case owner.TaskID == taskID && (owner.WorkspaceID == "" || owner.WorkspaceID == workspaceID):
		// Upgrade legacy task-only markers while the lock makes the rewrite
		// exclusive. Disk usage can then attribute active roots by workspace.
		if owner.WorkspaceID == "" {
			if err := writeEnvRootOwner(envRoot, workspaceID, taskID); err != nil {
				return nil, false, err
			}
		}
		// Ours, and the execution that left it is provably gone — we hold the
		// lock it would still be holding.
		return lockFile, true, nil
	case owner.TaskID != "":
		return nil, false, fmt.Errorf("env root %s belongs to task %s in workspace %s; refusing to reset it for task %s in workspace %s", envRoot, owner.TaskID, owner.WorkspaceID, taskID, workspaceID)
	}

	// No owner recorded. Either the directory is new, or a crash tore the
	// marker before it named anyone. Work with no owner is never ours to
	// delete; an env root with nothing in it costs nothing to adopt.
	hasWork, err := envRootHoldsWork(envRoot)
	if err != nil {
		return nil, false, fmt.Errorf("inspect env root %s: %w", envRoot, err)
	}
	if hasWork {
		return nil, false, fmt.Errorf("env root %s already holds files but names no owning task; refusing to delete it", envRoot)
	}
	if err := writeEnvRootOwner(envRoot, workspaceID, taskID); err != nil {
		return nil, false, err
	}
	return lockFile, false, nil
}

// ReleaseLock drops the env root's execution lock. The daemon defers this for
// the duration of a task run: the lock's lifetime is the EXECUTION, not this
// value. Cleanup is not the right place on its own — production never calls it
// (the GC reclaims env roots later), so a lock released only there would be
// held until the daemon exits and would fail-closed every legitimate rerun of
// that task. Safe on nil and safe to call twice.
func (env *Environment) ReleaseLock() {
	if env == nil || env.lockFile == nil {
		return
	}
	releaseLockFile(env.lockFile)
	env.lockFile = nil
}

// releaseLockFile drops the execution lock and closes the file. Safe on nil.
func releaseLockFile(f *os.File) {
	if f == nil {
		return
	}
	_ = unlockFile(f)
	_ = f.Close()
}

// writeEnvRootOwner records authoritative workspace/task identity. Callers
// must hold the env root lock, which makes overwriting a torn or legacy marker
// safe from another execution racing mid-claim. The same-directory temp file
// and rename keep lock-free readers from observing a truncated JSON marker.
func writeEnvRootOwner(envRoot, workspaceID, taskID string) error {
	path := filepath.Join(envRoot, envRootOwnerFile)
	data, err := json.Marshal(EnvRootOwner{WorkspaceID: workspaceID, TaskID: taskID})
	if err != nil {
		return fmt.Errorf("encode env root owner for %s: %w", envRoot, err)
	}

	tmp, err := os.CreateTemp(envRoot, envRootOwnerTempPrefix+"*"+envRootOwnerTempSuffix)
	if err != nil {
		return fmt.Errorf("create temp env root owner for %s: %w", envRoot, err)
	}
	tmpPath := tmp.Name()
	defer os.Remove(tmpPath)

	if _, err := tmp.Write(data); err != nil {
		tmp.Close()
		return fmt.Errorf("write temp env root owner for %s: %w", envRoot, err)
	}
	if err := tmp.Chmod(0o644); err != nil {
		tmp.Close()
		return fmt.Errorf("chmod temp env root owner for %s: %w", envRoot, err)
	}
	if err := tmp.Sync(); err != nil {
		tmp.Close()
		return fmt.Errorf("sync temp env root owner for %s: %w", envRoot, err)
	}
	if err := tmp.Close(); err != nil {
		return fmt.Errorf("close temp env root owner for %s: %w", envRoot, err)
	}
	if err := os.Rename(tmpPath, path); err != nil {
		return fmt.Errorf("replace env root owner for %s: %w", envRoot, err)
	}
	return nil
}

// removeStaleEnvRootOwnerTemps clears unpublished files left by a process that
// exited before the atomic rename. Callers hold the env root lock, so no live
// owner write can be using one of these files.
func removeStaleEnvRootOwnerTemps(envRoot string) error {
	entries, err := os.ReadDir(envRoot)
	if err != nil {
		return err
	}
	for _, entry := range entries {
		name := entry.Name()
		if !strings.HasPrefix(name, envRootOwnerTempPrefix) || !strings.HasSuffix(name, envRootOwnerTempSuffix) {
			continue
		}
		if err := os.RemoveAll(filepath.Join(envRoot, name)); err != nil {
			return err
		}
	}
	return nil
}

// readEnvRootOwner returns the task id that owns envRoot, or "" when no marker
// is present or it was never written through. An unreadable marker is an
// error, not an empty owner: treating it as unowned would hand the caller a
// licence to delete the very directory it could not identify.
func readEnvRootOwner(envRoot string) (string, error) {
	owner, err := ReadEnvRootOwner(envRoot)
	if err != nil {
		return "", err
	}
	return owner.TaskID, nil
}

// EnvRootOwner is written before any task content so active and partially
// prepared roots retain authoritative identity without completion metadata.
type EnvRootOwner struct {
	WorkspaceID string `json:"workspace_id,omitempty"`
	TaskID      string `json:"task_id"`
}

// ReadEnvRootOwner reads both current JSON markers and legacy plain task IDs.
func ReadEnvRootOwner(envRoot string) (*EnvRootOwner, error) {
	b, err := os.ReadFile(filepath.Join(envRoot, envRootOwnerFile))
	if errors.Is(err, os.ErrNotExist) {
		return &EnvRootOwner{}, nil
	}
	if err != nil {
		return nil, err
	}
	trimmed := strings.TrimSpace(string(b))
	if !strings.HasPrefix(trimmed, "{") {
		return &EnvRootOwner{TaskID: trimmed}, nil
	}
	var owner EnvRootOwner
	if err := json.Unmarshal(b, &owner); err != nil {
		return nil, err
	}
	owner.TaskID = strings.TrimSpace(owner.TaskID)
	owner.WorkspaceID = strings.TrimSpace(owner.WorkspaceID)
	return &owner, nil
}

// resetEnvRootContents empties an env root the caller already owns and holds
// the lock on, keeping the bookkeeping files. Removing and recreating the
// directory instead would drop both the claim and the lock for as long as the
// recreate takes, which is exactly the window claimEnvRoot exists to close.
func resetEnvRootContents(envRoot string) error {
	entries, err := os.ReadDir(envRoot)
	if err != nil {
		return err
	}
	for _, e := range entries {
		if isEnvRootBookkeeping(e.Name()) {
			continue
		}
		if err := os.RemoveAll(filepath.Join(envRoot, e.Name())); err != nil {
			return err
		}
	}
	return nil
}

// envRootHoldsWork reports whether envRoot contains anything beyond the owner
// marker and the lock file — that is, anything a task could lose.
func envRootHoldsWork(envRoot string) (bool, error) {
	entries, err := os.ReadDir(envRoot)
	if err != nil {
		return false, err
	}
	for _, e := range entries {
		if !isEnvRootBookkeeping(e.Name()) {
			return true, nil
		}
	}
	return false, nil
}

func isEnvRootBookkeeping(name string) bool {
	if name == envRootOwnerFile || name == envRootLockFile {
		return true
	}
	// An unpublished owner temp is a crash leftover from writeEnvRootOwner, not
	// task content. claimEnvRoot clears these before it looks, but
	// findOwnedTaskRoot inspects candidate roots WITHOUT the lock — and reading
	// one as work makes adoption refuse a root that holds nothing a task could
	// lose, wedging that task permanently.
	return strings.HasPrefix(name, envRootOwnerTempPrefix) &&
		strings.HasSuffix(name, envRootOwnerTempSuffix)
}