P3: store group — kv_* + file_* tools (agent memory)

RegisterStore(reg, StoreDeps) registers the persistent-memory tools over the
host's KV and/or File backends:
- kv_get/set/list/delete (KVStorage seam)
- file_save/get/get_text/get_metadata/list/delete (FileStorage seam), plus
  file_search (FileSearcher) and create_file_url (FileTokenMinter) when wired.

Near-zero-config: Quota defaults to a generous static cap (staticQuota), the
per-value/per-file caps default, and the kv vs file groups register
independently (a host can take just one). Seams moved clean (interface-only):
kv_storage.go, quota_provider.go, file_descendant_grant.go. The default
in-memory KV/File backends come with contrib/store at P4.

Core go.sum still free of gorm/redis/discordgo/sqlite.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -60,11 +60,12 @@ CORE (majordomo + stdlib):
   compact/  context compactor (WithCompactor hook)       [P2 ✓]
   tools/    generic tool library: Register (think/now/    [P3 wip]
             cite, zero-config) + RegisterMeta (classify/
-            extract_entities/summarize); seams in
-            research_providers.go/file_storage.go;
-            in-memory budget default. End-to-end "agent
-            calls a tool" test green. Remaining: web/net/
-            store/compose groups + their backends         [P3]
+            extract_entities/summarize) + RegisterStore
+            (kv_*/file_*, default static quota); seams in
+            research_providers.go/file_storage.go/
+            kv_storage.go/quota_provider.go. End-to-end
+            "agent calls a tool" test green. Remaining:
+            web/net/compose groups + default backends     [P3]
 
 BATTERIES (opt-in siblings, each nil-safe + a default):
   persona/   Agent noun + AgentStore seam + yml loader   [P4]

tools/create_file_url.go

@@ -0,0 +1,196 @@
+// create_file_url mints a public-token URL (mort.sh/files/<token>)
+// that resolves to a saved file_id. Use it for artifacts that are too
+// large for Discord (>25 MiB), need a stable link to share outside
+// Discord, or where the recipient is not in mort's auth domain.
+//
+// Why a separate tool (vs always returning a URL from file_save):
+// most files are private working state — only some need a public URL,
+// and minting one is a deliberate act. Decoupling save from
+// publication keeps the storage layer cheap (no token row per file)
+// and the audit clean (you can grep skill_file_tokens for "who
+// published what").
+//
+// Cycle-break: this tool can't import pkg/logic/skills directly
+// (pkg/logic/skills imports pkg/skilltools). The narrow interface
+// FileTokenMinter is declared here; mort.go bridges to
+// *skills.System.Storage() at wiring time.
+package tools
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+// FileToken is the wire-shape of the storage row that backs the
+// public /files/<token> URL. Mirrors pkg/logic/skills.FileToken
+// field-for-field; the adapter in mort.go is a struct copy.
+//
+// Why mirror (vs import skills.FileToken): same cycle constraint as
+// FileDomainMeta / KVDomainEntry — the tool layer cannot import
+// pkg/logic/skills.
+type FileToken struct {
+	Token     string
+	FileID    string
+	SkillID   string
+	CallerID  string
+	CreatedAt time.Time
+	ExpiresAt *time.Time
+	MaxViews  *int
+	Views     int
+}
+
+// FileTokenMinter is the narrow interface the create_file_url tool
+// needs to persist a new token. Production wires to
+// *skills.gormStorage via a thin adapter in mort.go.
+type FileTokenMinter interface {
+	SaveFileToken(ctx context.Context, t FileToken) error
+}
+
+// Caps for create_file_url. Public so tests can assert against them.
+const (
+	// DefaultFileURLExpiry is the default lifetime applied when the
+	// caller doesn't supply expires_in_seconds.
+	DefaultFileURLExpiry = 24 * time.Hour
+	// MaxFileURLExpiry is the per-tool hard cap. 30 days is generous
+	// enough for "share this report with someone" without becoming
+	// effectively-permanent. Operators can lower via the
+	// SkillFileURLConfigProvider; this is the floor below which the
+	// admin gate doesn't apply.
+	MaxFileURLExpiry = 30 * 24 * time.Hour
+	// MaxFileURLViews is the per-tool hard cap on max_views. 1000 is
+	// the largest value an LLM might plausibly set; anything beyond
+	// is "unlimited" semantically and the caller should leave the
+	// field absent.
+	MaxFileURLViews = 1000
+)
+
+type createFileURLArgs struct {
+	FileID           string `json:"file_id" description:"file_id previously saved by this skill (from file_save, code_exec, etc)."`
+	ExpiresInSeconds int    `json:"expires_in_seconds,omitempty" description:"How long the URL stays valid in seconds. Default 86400 (24h). Max 2592000 (30 days)."`
+	MaxViews         int    `json:"max_views,omitempty" description:"Optional cap on the number of times the URL can be fetched. Max 1000. Omit (or 0) for unlimited within the lifetime."`
+}
+
+type createFileURLResult struct {
+	URL       string `json:"url"`
+	Token     string `json:"token"`
+	ExpiresAt string `json:"expires_at,omitempty"` // RFC3339
+	MaxViews  int    `json:"max_views,omitempty"`
+	Note      string `json:"note,omitempty"`
+}
+
+// NewCreateFileURL constructs the create_file_url tool. nil minter →
+// "not configured" at execute time; nil fileStorage same. baseURL is
+// the public site (e.g. "https://mort.sh"); the path "/files/<token>"
+// is appended.
+//
+// Permission shape: anyone-authoring + caller-scope + share-safe +
+// files/discord/composition. The "publishing" act is a tool call,
+// not a save-time / share-time concern — every caller of a shared
+// skill mints into their own audit trail.
+func NewCreateFileURL(minter FileTokenMinter, fileStorage FileStorage, baseURL string) tool.Tool {
+	baseURL = strings.TrimRight(baseURL, "/")
+	return tool.NewGatedTool[createFileURLArgs](
+		"create_file_url",
+		"Mint a public URL (mort.sh/files/<token>) for a saved file_id. Use for files too large for Discord (>25 MiB) or when a stable link is preferred over an attachment. Default expiry 24h; max 30 days. Optional view-count cap (max 1000).",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"files", "discord"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args createFileURLArgs) (string, error) {
+			if minter == nil || fileStorage == nil {
+				return "", fmt.Errorf("create_file_url: not configured")
+			}
+			if strings.TrimSpace(args.FileID) == "" {
+				return "", fmt.Errorf("create_file_url: file_id required")
+			}
+
+			// Cross-skill rejection: the file MUST belong to the
+			// calling skill. Without this, a hostile skill could mint
+			// a URL for ANY file by file_id.
+			meta, _, err := fileStorage.FileGet(ctx, args.FileID)
+			if err != nil {
+				if errors.Is(err, ErrFileNotFound) {
+					return "", fmt.Errorf("create_file_url: file_id %q not found", args.FileID)
+				}
+				return "", fmt.Errorf("create_file_url: %w", err)
+			}
+			if meta.SkillID != inv.SkillID && !descendantFileGrant(ctx, fileStorage, inv, meta.SkillID) {
+				return "", fmt.Errorf("create_file_url: file_id %q does not belong to this skill (cross-skill refs rejected)", args.FileID)
+			}
+
+			// Resolve expiry.
+			expiry := DefaultFileURLExpiry
+			if args.ExpiresInSeconds > 0 {
+				expiry = time.Duration(args.ExpiresInSeconds) * time.Second
+			}
+			if expiry > MaxFileURLExpiry {
+				expiry = MaxFileURLExpiry
+			}
+			expiresAt := time.Now().Add(expiry)
+
+			// Resolve max_views.
+			var maxViews *int
+			if args.MaxViews > 0 {
+				mv := args.MaxViews
+				if mv > MaxFileURLViews {
+					mv = MaxFileURLViews
+				}
+				maxViews = &mv
+			}
+
+			// Mint a 32-byte random token, base64url-encoded
+			// (padless). 43 chars long; the storage column is 64 so
+			// there's room to grow without a migration.
+			token, err := mintFileURLToken()
+			if err != nil {
+				return "", fmt.Errorf("create_file_url: token generation: %w", err)
+			}
+
+			// Persist.
+			if err := minter.SaveFileToken(ctx, FileToken{
+				Token:     token,
+				FileID:    args.FileID,
+				SkillID:   inv.SkillID,
+				CallerID:  inv.CallerID,
+				ExpiresAt: &expiresAt,
+				MaxViews:  maxViews,
+			}); err != nil {
+				return "", fmt.Errorf("create_file_url: save: %w", err)
+			}
+
+			url := baseURL + "/files/" + token
+			res := createFileURLResult{
+				URL:       url,
+				Token:     token,
+				ExpiresAt: expiresAt.UTC().Format(time.RFC3339),
+				Note:      "URL is public — anyone with the link can fetch this file until it expires or the view cap is reached.",
+			}
+			if maxViews != nil {
+				res.MaxViews = *maxViews
+			}
+			b, _ := json.Marshal(res)
+			return string(b), nil
+		},
+	)
+}
+
+// mintFileURLToken returns a 32-byte random token, base64url-encoded
+// without padding. ~190 bits of entropy, well above the
+// collision-resistance threshold for the 64-char storage column.
+func mintFileURLToken() (string, error) {
+	var b [32]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return "", err
+	}
+	return base64.RawURLEncoding.EncodeToString(b[:]), nil
+}

tools/file_delete.go

@@ -0,0 +1,70 @@
+// file_delete removes a saved file by its file_id. Decrements the
+// underlying blob's refcount in storage; the blob row is removed when
+// refcount hits zero.
+//
+// Why scope is checked POST-fetch (mirrors file_get): file_id is the
+// only key the caller has; we must read the row to know the scope.
+package tools
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+type fileDeleteArgs struct {
+	FileID string `json:"file_id" description:"Opaque file ID returned by file_save or file_list."`
+}
+
+// NewFileDelete constructs the file_delete tool. storage nil → "not
+// configured" at execute time.
+func NewFileDelete(storage FileStorage) tool.Tool {
+	return tool.NewGatedTool[fileDeleteArgs](
+		"file_delete",
+		"Remove a saved file by file_id. Returns 'ok' on success or 'not_found' if no file matched.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "write"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileDeleteArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("file_delete: not configured")
+			}
+			if args.FileID == "" {
+				return "", fmt.Errorf("file_delete: file_id required")
+			}
+
+			// Fetch first so we can validate scope before deleting. The
+			// extra read is acceptable for a write path that's not in
+			// the hot loop, and it preserves the cross-skill /
+			// cross-user safety story.
+			meta, _, err := storage.FileGet(ctx, args.FileID)
+			if err != nil {
+				if errors.Is(err, ErrFileNotFound) {
+					return "not_found", nil
+				}
+				return "", fmt.Errorf("file_delete: %w", err)
+			}
+			if meta.SkillID != inv.SkillID {
+				return "", fmt.Errorf("file_delete: file does not belong to this skill")
+			}
+			if err := ValidateScope(inv, meta.Scope, false); err != nil {
+				return "", fmt.Errorf("file_delete: %w", err)
+			}
+
+			if err := storage.FileDelete(ctx, args.FileID); err != nil {
+				if errors.Is(err, ErrFileNotFound) {
+					// Race: row was deleted between FileGet and
+					// FileDelete. Surface as a clean miss.
+					return "not_found", nil
+				}
+				return "", fmt.Errorf("file_delete: %w", err)
+			}
+			return "ok", nil
+		},
+	)
+}

tools/file_descendant_grant.go

@@ -0,0 +1,58 @@
+// file_descendant_grant.go — the cross-skill file-access escape hatch
+// for parent → spawned-worker handoff.
+//
+// The blanket rule everywhere in this package is "a file belongs to
+// the skill that saved it; cross-skill refs are rejected". That rule
+// breaks the agent_spawn flow: a worker saves a chart with file_save
+// under ITS ephemeral ID, returns the file_id as text, and the parent
+// (which orchestrated the whole thing) can't attach, read, or host it.
+// Observed live on the second spawn test — the chart never reached
+// Discord; general could only apologise with the file_id.
+//
+// The grant: a caller may access a file whose owning skill/agent
+// PRODUCED A RUN THAT DESCENDS FROM THE CALLER'S CURRENT RUN. In other
+// words: you may touch the artifacts of workers you (transitively)
+// dispatched in this very tree — output you were already entitled to
+// see as their tool results. You may NOT touch files from siblings,
+// ancestors, other trees, or unrelated skills; those still reject.
+//
+// Why an optional interface upgrade (vs a new constructor dep on
+// every file tool): six tools enforce the ownership rule, each with
+// its own narrow storage interface — threading a new dep through all
+// of them churns every signature and test fake. Instead, the
+// production storage adapter (mort.go's skillsFileStorageAdapter,
+// which backs ALL of those interfaces) additionally implements
+// DescendantRunChecker; the tools type-assert at the rejection site.
+// Fakes that don't implement it keep the strict behaviour — the grant
+// is fail-closed everywhere. Same pattern as KVHistoryRecorder (v7).
+package tools
+
+import (
+	"context"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+// DescendantRunChecker reports whether ownerSkillID (the file's owning
+// skill or agent ID — e.g. a spawned worker's "eph-…" ID) produced a
+// run that is a DESCENDANT of callerRunID. Production walks the audit
+// parent_run_id chain; see mort_skills_storage_adapters.go.
+type DescendantRunChecker interface {
+	IsDescendantProducer(ctx context.Context, ownerSkillID, callerRunID string) (bool, error)
+}
+
+// descendantFileGrant is called at a cross-skill rejection site with
+// the tool's storage dep. Returns true only when the dep implements
+// DescendantRunChecker AND the owner's run descends from the caller's
+// run. Any error or missing context keeps the strict rejection.
+func descendantFileGrant(ctx context.Context, dep any, inv tool.Invocation, ownerSkillID string) bool {
+	if ownerSkillID == "" || inv.RunID == "" {
+		return false
+	}
+	checker, ok := dep.(DescendantRunChecker)
+	if !ok || checker == nil {
+		return false
+	}
+	granted, err := checker.IsDescendantProducer(ctx, ownerSkillID, inv.RunID)
+	return err == nil && granted
+}

tools/file_get.go

@@ -0,0 +1,103 @@
+// file_get fetches a previously-saved file by its opaque file_id and
+// returns the metadata + base64-encoded bytes.
+//
+// Why scope is checked POST-fetch: file_id is the only key the caller
+// knows; the scope (and therefore the authorisation envelope) is
+// stored on the FileMeta row. We must read the row first to know which
+// scope to validate. The trade-off is that file_id existence is
+// observable (a foreign caller can probe IDs and learn that one
+// exists), but the bytes themselves are still gated. file_id is a UUID,
+// so the probe surface is impractical.
+//
+// Why base64 in the response: same reason as file_save — JSON can't
+// carry arbitrary bytes natively. Callers that want a paste link or a
+// direct download go through a separate path.
+package tools
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+type fileGetArgs struct {
+	FileID string `json:"file_id" description:"Opaque file ID returned by file_save or file_list."`
+}
+
+type fileGetResult struct {
+	Name          string `json:"name"`
+	ContentBase64 string `json:"content_base64"`
+	Mime          string `json:"mime"`
+	SizeBytes     int64  `json:"size_bytes"`
+	CreatedAt     string `json:"created_at"` // RFC3339
+}
+
+// NewFileGet constructs the file_get tool. storage nil → "not
+// configured" at execute time.
+func NewFileGet(storage FileStorage) tool.Tool {
+	return tool.NewGatedTool[fileGetArgs](
+		"file_get",
+		"Fetch a saved file by its file_id. Returns name, base64 content, MIME, size, and created_at. The caller must have access to the file's scope (skill / own user: / own run:).",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileGetArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("file_get: not configured")
+			}
+			if args.FileID == "" {
+				return "", fmt.Errorf("file_get: file_id required")
+			}
+
+			meta, content, err := storage.FileGet(ctx, args.FileID)
+			if err != nil {
+				if errors.Is(err, ErrFileNotFound) {
+					return "", fmt.Errorf("file_get: not found")
+				}
+				return "", fmt.Errorf("file_get: %w", err)
+			}
+
+			// Cross-skill access check: a file's SkillID must match the
+			// current invocation's SkillID. Without this, a caller
+			// could probe another skill's file_ids and read content.
+			// One exception — the descendant grant (see
+			// file_descendant_grant.go): workers this run dispatched.
+			grantedViaDescendant := false
+			if meta.SkillID != inv.SkillID {
+				if !descendantFileGrant(ctx, storage, inv, meta.SkillID) {
+					return "", fmt.Errorf("file_get: file does not belong to this skill")
+				}
+				grantedViaDescendant = true
+			}
+
+			// Scope check: even within the same skill, the scope on the
+			// row gates access (e.g. user:bob's file is unreadable by
+			// alice). The descendant grant stands in for it — the file's
+			// scope is the WORKER's run, never the caller's.
+			if err := ValidateScope(inv, meta.Scope, false); err != nil && !grantedViaDescendant {
+				return "", fmt.Errorf("file_get: %w", err)
+			}
+
+			res := fileGetResult{
+				Name:          meta.Name,
+				ContentBase64: base64.StdEncoding.EncodeToString(content),
+				Mime:          meta.MimeType,
+				SizeBytes:     meta.SizeBytes,
+				CreatedAt:     meta.CreatedAt.UTC().Format(time.RFC3339),
+			}
+			b, err := json.Marshal(res)
+			if err != nil {
+				return "", fmt.Errorf("file_get: marshal: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}

tools/file_get_metadata.go

@@ -0,0 +1,91 @@
+// file_get_metadata returns metadata about a saved file (name, mime,
+// size, created_at) WITHOUT loading the bytes. This is the v10
+// agent-friendly companion to file_get — agents that just need to
+// reason about a file's properties (size, type, name) should use
+// file_get_metadata instead of pulling the full body into the context
+// window.
+//
+// Why a separate tool (vs adding a flag to file_get): the byte-vs-
+// reference principle is enforced statically — file_get_metadata's
+// return shape simply does not carry bytes, so agents and tool
+// authors can rely on the type signature. A flag-gated variant would
+// invite "what does include_content=false mean" confusion.
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+type fileGetMetadataArgs struct {
+	FileID string `json:"file_id" description:"Opaque file ID returned by file_save or file_list."`
+}
+
+type fileGetMetadataResult struct {
+	Name      string `json:"name"`
+	Mime      string `json:"mime"`
+	SizeBytes int64  `json:"size_bytes"`
+	CreatedAt string `json:"created_at"` // RFC3339
+	Scope     string `json:"scope"`
+}
+
+// NewFileGetMetadata constructs the file_get_metadata tool. storage
+// nil → "not configured" at execute time.
+func NewFileGetMetadata(storage FileStorage) tool.Tool {
+	return tool.NewGatedTool[fileGetMetadataArgs](
+		"file_get_metadata",
+		"Fetch metadata for a saved file by its file_id (name, mime, size_bytes, created_at, scope). Does NOT load the file bytes — use file_get_text for text content or send_attachments to ship binary content to Discord.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileGetMetadataArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("file_get_metadata: not configured")
+			}
+			if args.FileID == "" {
+				return "", fmt.Errorf("file_get_metadata: file_id required")
+			}
+			meta, _, err := storage.FileGet(ctx, args.FileID)
+			if err != nil {
+				if errors.Is(err, ErrFileNotFound) {
+					return "", fmt.Errorf("file_get_metadata: not found")
+				}
+				return "", fmt.Errorf("file_get_metadata: %w", err)
+			}
+			// Descendant grant: see file_descendant_grant.go — covers
+			// the scope check too (the file's scope is the worker's run).
+			grantedViaDescendant := false
+			if meta.SkillID != inv.SkillID {
+				if !descendantFileGrant(ctx, storage, inv, meta.SkillID) {
+					return "", fmt.Errorf("file_get_metadata: file does not belong to this skill")
+				}
+				grantedViaDescendant = true
+			}
+			if !grantedViaDescendant {
+				if err := ValidateScope(inv, meta.Scope, false); err != nil {
+					return "", fmt.Errorf("file_get_metadata: %w", err)
+				}
+			}
+			res := fileGetMetadataResult{
+				Name:      meta.Name,
+				Mime:      meta.MimeType,
+				SizeBytes: meta.SizeBytes,
+				CreatedAt: meta.CreatedAt.UTC().Format(time.RFC3339),
+				Scope:     meta.Scope,
+			}
+			b, err := json.Marshal(res)
+			if err != nil {
+				return "", fmt.Errorf("file_get_metadata: marshal: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}

tools/file_get_text.go

@@ -0,0 +1,119 @@
+// file_get_text fetches a saved text file's content as plain text.
+// Only succeeds for text/* MIMEs; binary MIMEs return an error so the
+// agent knows to use a different path (file_get_metadata for
+// reasoning, send_attachments for delivery).
+//
+// Why a 64 KiB cap: the v10 byte-vs-reference principle says inline
+// text content stays under ~10KB ideally; we set the hard cap at 64
+// KiB to handle reasonable text artifacts (logs, configs, small
+// reports) without blowing the agent's context. Files larger than
+// the cap return an error pointing to send_attachments.
+//
+// Why a separate tool (vs file_get): file_get returns base64 +
+// metadata regardless of MIME, which agents misuse to dump 10MB PDFs
+// into the context window. file_get_text is the agent-friendly
+// alternative that explicitly fails fast on binary content.
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+const fileGetTextMaxBytes = 64 * 1024
+
+type fileGetTextArgs struct {
+	FileID string `json:"file_id" description:"Opaque file ID returned by file_save or file_list."`
+}
+
+type fileGetTextResult struct {
+	Text      string `json:"text"`
+	Mime      string `json:"mime"`
+	SizeBytes int64  `json:"size_bytes"`
+	CreatedAt string `json:"created_at"` // RFC3339
+}
+
+// NewFileGetText constructs the file_get_text tool. storage nil →
+// "not configured" at execute time.
+func NewFileGetText(storage FileStorage) tool.Tool {
+	return tool.NewGatedTool[fileGetTextArgs](
+		"file_get_text",
+		"Fetch a saved text file's content (text/* MIMEs only, capped at 64KB). For binary content use file_get_metadata + send_attachments. Errors with 'not_text' for non-text MIMEs and 'too_large' for files > 64KB.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileGetTextArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("file_get_text: not configured")
+			}
+			if args.FileID == "" {
+				return "", fmt.Errorf("file_get_text: file_id required")
+			}
+			meta, content, err := storage.FileGet(ctx, args.FileID)
+			if err != nil {
+				if errors.Is(err, ErrFileNotFound) {
+					return "", fmt.Errorf("file_get_text: not found")
+				}
+				return "", fmt.Errorf("file_get_text: %w", err)
+			}
+			// Descendant grant: a worker this run (transitively)
+			// dispatched may have produced the file — its scope is the
+			// WORKER's run, so the grant also stands in for the scope
+			// check below.
+			grantedViaDescendant := false
+			if meta.SkillID != inv.SkillID {
+				if !descendantFileGrant(ctx, storage, inv, meta.SkillID) {
+					return "", fmt.Errorf("file_get_text: file does not belong to this skill")
+				}
+				grantedViaDescendant = true
+			}
+			if !grantedViaDescendant {
+				if err := ValidateScope(inv, meta.Scope, false); err != nil {
+					return "", fmt.Errorf("file_get_text: %w", err)
+				}
+			}
+			if !isTextMime(meta.MimeType) {
+				return "", fmt.Errorf("file_get_text: not_text: mime %q is not text/*", meta.MimeType)
+			}
+			if int64(len(content)) > fileGetTextMaxBytes {
+				return "", fmt.Errorf("file_get_text: too_large: %d bytes exceeds 64KB cap; use send_attachments to deliver this file to Discord", len(content))
+			}
+			res := fileGetTextResult{
+				Text:      string(content),
+				Mime:      meta.MimeType,
+				SizeBytes: meta.SizeBytes,
+				CreatedAt: meta.CreatedAt.UTC().Format(time.RFC3339),
+			}
+			b, err := json.Marshal(res)
+			if err != nil {
+				return "", fmt.Errorf("file_get_text: marshal: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}
+
+// isTextMime reports whether the given MIME is a text/* type.
+// Accepts "text/plain", "text/markdown", "text/csv", "application/json"
+// and "application/xml" since those are conventionally text.
+func isTextMime(mime string) bool {
+	mime = strings.ToLower(strings.TrimSpace(mime))
+	if strings.HasPrefix(mime, "text/") {
+		return true
+	}
+	switch mime {
+	case "application/json", "application/xml", "application/xhtml+xml",
+		"application/javascript", "application/yaml", "application/x-yaml":
+		return true
+	}
+	return false
+}

tools/file_list.go

@@ -0,0 +1,74 @@
+// file_list returns metadata for files in a scope. Blob bytes are NOT
+// loaded — listing is a hot path that must stay light, and the LLM
+// would burn tokens for no benefit.
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+type fileListArgs struct {
+	Scope string `json:"scope" description:"Storage scope: 'skill', 'user:<your_id>', or 'run:<run_id>'."`
+}
+
+type fileListEntry struct {
+	FileID    string `json:"file_id"`
+	Name      string `json:"name"`
+	Mime      string `json:"mime"`
+	SizeBytes int64  `json:"size_bytes"`
+	CreatedAt string `json:"created_at"`
+}
+
+// NewFileList constructs the file_list tool. storage nil → "not
+// configured" at execute time.
+func NewFileList(storage FileStorage) tool.Tool {
+	return tool.NewGatedTool[fileListArgs](
+		"file_list",
+		"List files in a scope. Returns a JSON array of {file_id, name, mime, size_bytes, created_at}. Does NOT include bytes — call file_get with a file_id to fetch content.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileListArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("file_list: not configured")
+			}
+			if err := ValidateScope(inv, args.Scope, false); err != nil {
+				return "", fmt.Errorf("file_list: %w", err)
+			}
+			// root_run is a KV-only scope (v1) — see file_save's guard.
+			if strings.HasPrefix(args.Scope, "root_run:") {
+				return "", fmt.Errorf("file_list: root_run scope is KV-only")
+			}
+
+			rows, err := storage.FileList(ctx, inv.SkillID, args.Scope)
+			if err != nil {
+				return "", fmt.Errorf("file_list: %w", err)
+			}
+
+			out := make([]fileListEntry, 0, len(rows))
+			for _, r := range rows {
+				out = append(out, fileListEntry{
+					FileID:    r.ID,
+					Name:      r.Name,
+					Mime:      r.MimeType,
+					SizeBytes: r.SizeBytes,
+					CreatedAt: r.CreatedAt.UTC().Format(time.RFC3339),
+				})
+			}
+			b, err := json.Marshal(out)
+			if err != nil {
+				return "", fmt.Errorf("file_list: marshal: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}

tools/file_save.go

@@ -0,0 +1,171 @@
+// file_save persists arbitrary bytes (base64-encoded by the caller)
+// against a (scope, name) tuple within the calling skill's namespace.
+// Returns the new file_id, the SHA256 content hash, and the size.
+//
+// Why base64 over raw bytes: the LLM's tool-call wire format is JSON,
+// which can't carry arbitrary bytes natively. Base64 round-trips
+// cleanly through the schema.
+//
+// Why hash + size in the response: agents commonly want to dedup
+// across runs (same hash = same content) or build a manifest. Reporting
+// these inline saves an immediate file_get round-trip just to compute
+// them.
+//
+// Per-file cap: maxFileBytes (constructor arg) enforces an upper bound
+// on individual file size. 0 falls back to defaultFileMaxBytes (10 MB).
+//
+// Per-skill quota (sum across all files): the constructor's QuotaProvider
+// arg drives the v4 Phase 4 enforcement. nil disables enforcement
+// (useful for tests and admin-only deployments). The check is:
+//
+//	used := storage.FileUsageBytes(skill)
+//	if used + len(new content) > filesMax → quota_exceeded
+//
+// Note we do NOT subtract a "prior" value here the way kv_set does:
+// file_save always inserts a new file row (content-addressable dedup
+// is at the blob layer, not the row layer), so every save is additive
+// to FileUsageBytes.
+package tools
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+const defaultFileMaxBytes = 10 * 1024 * 1024 // 10 MiB
+
+type fileSaveArgs struct {
+	Scope         string `json:"scope" description:"Storage scope: 'skill' (shared across all callers of this skill), 'user:<your_id>' (per-caller), or 'run:<run_id>' (this run's scratchpad)."`
+	Name          string `json:"name" description:"Filename including extension. Used for display only — the file is identified by an opaque file_id."`
+	ContentBase64 string `json:"content_base64" description:"Base64-encoded file content."`
+	Mime          string `json:"mime,omitempty" description:"Optional MIME type. If omitted, detected from the first 512 bytes of content."`
+}
+
+type fileSaveResult struct {
+	FileID    string `json:"file_id"`
+	Hash      string `json:"hash"`
+	SizeBytes int64  `json:"size_bytes"`
+}
+
+// NewFileSave constructs the file_save tool.
+//
+// storage nil → "not configured" at execute time.
+// maxFileBytes <= 0 falls back to defaultFileMaxBytes (10 MiB).
+// quota nil → per-skill quota check skipped (per-file cap still applies).
+//
+// Permission: anyone may author; safe for share. Scope check at handler
+// entry prevents cross-user writes; per-user buckets are isolated by
+// inv.CallerID.
+func NewFileSave(storage FileStorage, quota QuotaProvider, maxFileBytes int) tool.Tool {
+	if maxFileBytes <= 0 {
+		maxFileBytes = defaultFileMaxBytes
+	}
+	return tool.NewGatedTool[fileSaveArgs](
+		"file_save",
+		"Save base64-encoded bytes against a (scope, name) tuple. Returns file_id (opaque), SHA256 hash, and size_bytes. Content is dedup'd by hash — multiple file_save calls with identical bytes share storage. NOTE: for files produced inside code_exec, do NOT hand-encode base64 here (it corrupts) — write them to /workspace/ in the code_exec call and use the files_out file_id it returns.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "write"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileSaveArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("file_save: not configured")
+			}
+			if err := ValidateScope(inv, args.Scope, false); err != nil {
+				return "", fmt.Errorf("file_save: %w", err)
+			}
+			// root_run is a KV-only scope (v1): file storage partitions
+			// by the calling skill, so a root_run file would silently be
+			// invisible to siblings AND escape the run-scope sweeper.
+			// Reject loudly instead.
+			if strings.HasPrefix(args.Scope, "root_run:") {
+				return "", fmt.Errorf("file_save: root_run scope is KV-only; save under run:<run_id> and share the file_id via kv_set in the root_run scope")
+			}
+			if args.Name == "" {
+				return "", fmt.Errorf("file_save: name required")
+			}
+			if args.ContentBase64 == "" {
+				return "", fmt.Errorf("file_save: content_base64 required")
+			}
+
+			// Decode + cap. Decoding twice (once to count, once to
+			// store) would waste cycles; we decode once and check size
+			// after.
+			content, err := base64.StdEncoding.DecodeString(args.ContentBase64)
+			if err != nil {
+				return "", fmt.Errorf("file_save: invalid base64: %w", err)
+			}
+			if len(content) > maxFileBytes {
+				return "", fmt.Errorf("file_save: file exceeds max %d bytes (got %d)", maxFileBytes, len(content))
+			}
+
+			// Per-skill quota gate (v4 Phase 4). Skipped when quota is nil
+			// (tests / admin opt-out) so the per-file cap above is the
+			// only line of defence in that mode.
+			if quota != nil {
+				_, filesMax, err := quota.EffectiveQuota(ctx, inv.SkillID)
+				if err != nil {
+					return "", fmt.Errorf("file_save: quota lookup: %w", err)
+				}
+				used, err := storage.FileUsageBytes(ctx, inv.SkillID)
+				if err != nil {
+					return "", fmt.Errorf("file_save: usage check: %w", err)
+				}
+				if used+int64(len(content)) > filesMax {
+					return "", fmt.Errorf("file_save: quota_exceeded — %d/%d bytes used; ask admin for higher quota", used, filesMax)
+				}
+			}
+
+			// SHA256 for content-addressable dedup at the storage layer.
+			h := sha256.Sum256(content)
+			hashHex := hex.EncodeToString(h[:])
+
+			mime := args.Mime
+			if mime == "" {
+				// http.DetectContentType is documented to read at most
+				// the first 512 bytes; passing the full slice is fine.
+				mime = http.DetectContentType(content)
+			}
+
+			meta := FileDomainMeta{
+				ID:          uuid.NewString(),
+				SkillID:     inv.SkillID,
+				Scope:       args.Scope,
+				Name:        args.Name,
+				ContentHash: hashHex,
+				MimeType:    mime,
+				SizeBytes:   int64(len(content)),
+				CreatedAt:   time.Now(),
+			}
+
+			fileID, err := storage.FileSave(ctx, meta, content)
+			if err != nil {
+				return "", fmt.Errorf("file_save: %w", err)
+			}
+
+			res := fileSaveResult{
+				FileID:    fileID,
+				Hash:      hashHex,
+				SizeBytes: int64(len(content)),
+			}
+			b, err := json.Marshal(res)
+			if err != nil {
+				return "", fmt.Errorf("file_save: marshal result: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}

tools/file_search.go

@@ -0,0 +1,131 @@
+// file_search runs a token-AND search over the per-skill (or, for
+// admin authors, cross-skill) file index. Returns up to N matches with
+// {file_id, name, snippet, score}.
+//
+// Why admin-authoring only: a public skill could otherwise probe
+// other skills' file content via cross-skill search. Restricting the
+// tool's authoring requirement to admins blocks shared/public skills
+// from depending on file_search at all (it never appears in their
+// allowed-tool catalog at save time). Within a private skill,
+// admin-authored or otherwise, scope is per-call: the handler always
+// pins skill_id to inv.SkillID — no matter what the LLM-supplied scope
+// arg says — so a non-admin caller invoking an admin-authored public
+// skill cannot escape the skill's own bucket.
+//
+// Why use Storage's SearchFiles directly: token logic + scoring lives
+// in the skills package. The handler is a thin transcoder.
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+// FileSearcher is the narrow surface the file_search tool needs.
+// Production wiring (mort.go) bridges *skills.System.Storage().
+// nil-safe: a nil FileSearcher surfaces "not configured" at the first
+// call.
+type FileSearcher interface {
+	SearchFiles(ctx context.Context, skillID, scope, query string, limit int) ([]FileSearchDomainHit, error)
+}
+
+// FileSearchDomainHit mirrors skills.FileSearchHit (cycle-break domain
+// shape). The production adapter is a struct copy.
+type FileSearchDomainHit struct {
+	FileID   string
+	SkillID  string
+	Scope    string
+	Name     string
+	MimeType string
+	Snippet  string
+	Score    int
+}
+
+type fileSearchArgs struct {
+	Query string `json:"query" description:"Free-text search query. Tokenised, lowercased, ANDed."`
+	Scope string `json:"scope,omitempty" description:"Optional storage scope to restrict the search ('skill', 'user:<your_id>', 'run:<run_id>'). Empty = all scopes within this skill."`
+	Limit int    `json:"limit,omitempty" description:"Optional max hits to return (default 25, max 100)."`
+}
+
+type fileSearchHit struct {
+	FileID  string `json:"file_id"`
+	Name    string `json:"name"`
+	Mime    string `json:"mime,omitempty"`
+	Snippet string `json:"snippet,omitempty"`
+	Score   int    `json:"score"`
+}
+
+// NewFileSearch constructs the file_search tool. Authoring-required
+// admin so non-admins can't include this tool in shared/public skills
+// (the share-safety check rejects share+admin-only as private-only).
+//
+// Wait — if the tool is admin-authoring AND share-safe, an admin could
+// author a public skill that uses it. That's the desired flow: admin
+// curates the skill, but the privacy property still holds because the
+// handler PINS skill_id to inv.SkillID. A non-admin caller of the
+// public skill can ONLY search files within that skill's bucket, not
+// cross-skill.
+//
+// Setting SafeForShare=false would force this tool to be private-only;
+// that's needlessly restrictive. The privacy property comes from the
+// per-call skill_id pin, not from share-time gating.
+func NewFileSearch(searcher FileSearcher) tool.Tool {
+	return tool.NewGatedTool[fileSearchArgs](
+		"file_search",
+		"Full-text search over this skill's saved files. Returns array of {file_id, name, snippet, score} ordered by score desc. Tokens are lowercased + ANDed. Admin-authored only — non-admin callers of an admin-authored public skill still see only that skill's files.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAdmin,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args fileSearchArgs) (string, error) {
+			if searcher == nil {
+				return "", fmt.Errorf("file_search: not configured")
+			}
+			if args.Query == "" {
+				return "", fmt.Errorf("file_search: query required")
+			}
+			limit := args.Limit
+			if limit <= 0 {
+				limit = 25
+			}
+			if limit > 100 {
+				limit = 100
+			}
+			scope := args.Scope
+			if scope != "" {
+				if err := ValidateScope(inv, scope, false); err != nil {
+					return "", fmt.Errorf("file_search: %w", err)
+				}
+			}
+
+			// Pin skill_id to the invoking skill — even if the LLM
+			// supplies a different value somewhere, the handler always
+			// scopes to inv.SkillID. This is the privacy guarantee
+			// referenced in the package doc.
+			rows, err := searcher.SearchFiles(ctx, inv.SkillID, scope, args.Query, limit)
+			if err != nil {
+				return "", fmt.Errorf("file_search: %w", err)
+			}
+			out := make([]fileSearchHit, 0, len(rows))
+			for _, r := range rows {
+				out = append(out, fileSearchHit{
+					FileID:  r.FileID,
+					Name:    r.Name,
+					Mime:    r.MimeType,
+					Snippet: r.Snippet,
+					Score:   r.Score,
+				})
+			}
+			b, err := json.Marshal(out)
+			if err != nil {
+				return "", fmt.Errorf("file_search: marshal: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}

tools/kv_delete.go

@@ -0,0 +1,52 @@
+// kv_delete removes a single entry by (scope, key). Missing rows
+// surface as the literal string "not_found" rather than an error so the
+// LLM can reason "did this row exist?" without wrapping the call in
+// error handling.
+package tools
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+type kvDeleteArgs struct {
+	Scope string `json:"scope" description:"Storage scope: 'skill', 'user:<your_id>', 'run:<run_id>', or 'root_run:<root_run_id>'."`
+	Key   string `json:"key" description:"Key within the scope."`
+}
+
+// NewKVDelete constructs the kv_delete tool. storage nil → "not
+// configured" at execute time.
+func NewKVDelete(storage KVStorage) tool.Tool {
+	return tool.NewGatedTool[kvDeleteArgs](
+		"kv_delete",
+		"Remove an entry by (scope, key). Returns 'ok' on success or 'not_found' if no row matched.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "write"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args kvDeleteArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("kv_delete: not configured")
+			}
+			if err := ValidateScope(inv, args.Scope, false); err != nil {
+				return "", fmt.Errorf("kv_delete: %w", err)
+			}
+			if args.Key == "" {
+				return "", fmt.Errorf("kv_delete: key required")
+			}
+
+			if err := storage.KVDelete(ctx, kvPartition(inv, args.Scope), args.Scope, args.Key); err != nil {
+				if errors.Is(err, ErrKVNotFound) {
+					return "not_found", nil
+				}
+				return "", fmt.Errorf("kv_delete: %w", err)
+			}
+			return "ok", nil
+		},
+	)
+}

tools/kv_get.go

@@ -0,0 +1,63 @@
+// kv_get is the v4 KV-storage read tool. It looks up a single value by
+// (scope, key) within the calling skill's KV namespace and returns the
+// stored JSON value, or `null` when no row matches.
+//
+// Why "null" on miss (vs an error): the LLM's most natural use is
+// "fetch this if cached, otherwise compute and store". Miss-as-error
+// would force the agent to wrap every call in error handling; miss-as-
+// null collapses the happy path.
+package tools
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+type kvGetArgs struct {
+	Scope string `json:"scope" description:"Storage scope: 'skill' (shared across all callers of this skill), 'user:<your_id>' (per-caller), 'run:<run_id>' (this run's scratchpad), or 'root_run:<root_run_id>' (shared scratchpad of this whole dispatch tree — use to coordinate with parallel sibling workers)."`
+	Key   string `json:"key" description:"Key within the scope."`
+}
+
+// NewKVGet constructs the kv_get tool. storage may be nil — the tool
+// then surfaces "not configured" at execute time instead of failing
+// registration.
+//
+// Permission: anyone may author; safe for share. The scope check at
+// handler entry makes share-safety meaningful — a shared skill cannot
+// read another caller's `user:<id>` bucket because ValidateScope
+// rejects that.
+func NewKVGet(storage KVStorage) tool.Tool {
+	return tool.NewGatedTool[kvGetArgs](
+		"kv_get",
+		"Look up a value by key in this skill's storage. Returns the stored JSON value, or `null` if no row matches the (scope, key) tuple.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args kvGetArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("kv_get: not configured")
+			}
+			if err := ValidateScope(inv, args.Scope, false); err != nil {
+				return "", fmt.Errorf("kv_get: %w", err)
+			}
+			if args.Key == "" {
+				return "", fmt.Errorf("kv_get: key required")
+			}
+
+			entry, err := storage.KVGet(ctx, kvPartition(inv, args.Scope), args.Scope, args.Key)
+			if err != nil {
+				if errors.Is(err, ErrKVNotFound) {
+					return "null", nil
+				}
+				return "", fmt.Errorf("kv_get: %w", err)
+			}
+			return string(entry.Value), nil
+		},
+	)
+}

tools/kv_list.go

@@ -0,0 +1,88 @@
+// kv_list returns metadata (key, size, expiry) for entries within a
+// scope, optionally filtered by key prefix. Values are NOT loaded —
+// listing is a hot path that should stay light, and dumping every
+// value byte into the LLM context would burn tokens for no benefit.
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+const (
+	kvListDefaultLimit = 100
+	kvListMaxLimit     = 1000
+)
+
+type kvListArgs struct {
+	Scope  string `json:"scope" description:"Storage scope: 'skill', 'user:<your_id>', 'run:<run_id>', or 'root_run:<root_run_id>'."`
+	Prefix string `json:"prefix,omitempty" description:"Optional key-prefix filter. Empty matches all keys in the scope."`
+	Limit  int    `json:"limit,omitempty" description:"Max entries to return. Default 100, hard cap 1000."`
+}
+
+type kvListEntry struct {
+	Key       string `json:"key"`
+	SizeBytes int    `json:"size_bytes"`
+	// ExpiresAt is RFC3339 when set, "" otherwise. JSON serialised this
+	// way so the LLM can reason about it as a string field consistently
+	// (rather than null vs. missing key).
+	ExpiresAt string `json:"expires_at,omitempty"`
+}
+
+// NewKVList constructs the kv_list tool. storage nil → "not configured"
+// at execute time.
+func NewKVList(storage KVStorage) tool.Tool {
+	return tool.NewGatedTool[kvListArgs](
+		"kv_list",
+		"List keys + sizes + expiries in a scope (optionally filtered by key prefix). Returns a JSON array. Does NOT include values — call kv_get to fetch a specific value.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "read"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args kvListArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("kv_list: not configured")
+			}
+			if err := ValidateScope(inv, args.Scope, false); err != nil {
+				return "", fmt.Errorf("kv_list: %w", err)
+			}
+
+			limit := args.Limit
+			if limit <= 0 {
+				limit = kvListDefaultLimit
+			}
+			if limit > kvListMaxLimit {
+				limit = kvListMaxLimit
+			}
+
+			rows, err := storage.KVList(ctx, kvPartition(inv, args.Scope), args.Scope, args.Prefix, limit)
+			if err != nil {
+				return "", fmt.Errorf("kv_list: %w", err)
+			}
+
+			out := make([]kvListEntry, 0, len(rows))
+			for _, r := range rows {
+				e := kvListEntry{
+					Key:       r.Key,
+					SizeBytes: len(r.Value),
+				}
+				if r.ExpiresAt != nil {
+					e.ExpiresAt = r.ExpiresAt.Format(time.RFC3339)
+				}
+				out = append(out, e)
+			}
+
+			b, err := json.Marshal(out)
+			if err != nil {
+				return "", fmt.Errorf("kv_list: marshal: %w", err)
+			}
+			return string(b), nil
+		},
+	)
+}

tools/kv_set.go

@@ -0,0 +1,145 @@
+// kv_set is the v4 KV-storage write tool. It upserts (scope, key) →
+// value within the calling skill's namespace, with optional TTL.
+//
+// Per-value cap: the constructor takes maxValueBytes (typically read
+// from convar `skills.storage.kv_max_value_bytes`); 0 means use the
+// 64 KiB default.
+//
+// Per-skill quota (sum across all rows): the constructor's QuotaProvider
+// arg drives the v4 Phase 4 enforcement. nil disables enforcement
+// (useful for tests and admin-only deployments). The check is:
+//
+//	used := storage.KVUsageBytes(skill)
+//	delta := len(new value) - len(prior value if updating same key)
+//	if used + delta > kvMax → quota_exceeded
+//
+// We subtract the existing value's size on UPDATE so an in-place edit
+// of a hot key never trips the cap unless the new value is larger.
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+const defaultKVMaxValueBytes = 65536 // 64 KiB
+
+type kvSetArgs struct {
+	Scope      string          `json:"scope" description:"Storage scope: 'skill', 'user:<your_id>', 'run:<run_id>', or 'root_run:<root_run_id>' (shared across the whole dispatch tree)."`
+	Key        string          `json:"key" description:"Key within the scope."`
+	Value      json.RawMessage `json:"value" description:"JSON value to store. Must parse as valid JSON (object, array, string, number, bool, or null)."`
+	TTLSeconds *int            `json:"ttl_seconds,omitempty" description:"Optional TTL in seconds. The entry expires (and is lazy-purged on read) after this duration."`
+}
+
+// NewKVSet constructs the kv_set tool.
+//
+// storage nil → "not configured" at execute time.
+// maxValueBytes <= 0 falls back to defaultKVMaxValueBytes.
+// quota nil → per-skill quota check is skipped (per-value cap still
+// applies).
+func NewKVSet(storage KVStorage, quota QuotaProvider, maxValueBytes int) tool.Tool {
+	if maxValueBytes <= 0 {
+		maxValueBytes = defaultKVMaxValueBytes
+	}
+	return tool.NewGatedTool[kvSetArgs](
+		"kv_set",
+		"Set a value at the given scope+key. Optionally with a TTL after which the entry auto-expires.",
+		tool.Permission{
+			AuthoringRequirement: tool.RequirementAnyone,
+			OperatesOn:           tool.ScopeCaller,
+			SafeForShare:         true,
+			Categories:           []string{"storage", "write"},
+		},
+		func(ctx context.Context, inv tool.Invocation, args kvSetArgs) (string, error) {
+			if storage == nil {
+				return "", fmt.Errorf("kv_set: not configured")
+			}
+			if err := ValidateScope(inv, args.Scope, false); err != nil {
+				return "", fmt.Errorf("kv_set: %w", err)
+			}
+			if args.Key == "" {
+				return "", fmt.Errorf("kv_set: key required")
+			}
+			if len(args.Value) == 0 {
+				return "", fmt.Errorf("kv_set: value required")
+			}
+			if len(args.Value) > maxValueBytes {
+				return "", fmt.Errorf("kv_set: value exceeds max %d bytes (got %d)", maxValueBytes, len(args.Value))
+			}
+
+			// Validate JSON. The storage layer treats the raw bytes as
+			// opaque, but the LLM contract says "value is a JSON value"
+			// — surfacing a parse error here gives a friendlier message
+			// than letting an invalid blob round-trip and confuse the
+			// reader on a future kv_get.
+			var probe any
+			if err := json.Unmarshal(args.Value, &probe); err != nil {
+				return "", fmt.Errorf("kv_set: value is not valid JSON: %w", err)
+			}
+
+			partition := kvPartition(inv, args.Scope)
+
+			// Per-skill quota gate (v4 Phase 4). Skipped when quota is nil
+			// (tests / admin opt-out) so the per-value cap above is the
+			// only line of defence in that mode. Also skipped for the
+			// shared root_run partition — per-skill quota attribution is
+			// meaningless across the sentinel; the per-value cap above +
+			// the run-scope sweeper bound that partition's growth.
+			if quota != nil && partition == inv.SkillID {
+				kvMax, _, err := quota.EffectiveQuota(ctx, inv.SkillID)
+				if err != nil {
+					return "", fmt.Errorf("kv_set: quota lookup: %w", err)
+				}
+				used, err := storage.KVUsageBytes(ctx, inv.SkillID)
+				if err != nil {
+					return "", fmt.Errorf("kv_set: usage check: %w", err)
+				}
+				delta := int64(len(args.Value))
+				// On UPDATE, subtract the prior value's size so an
+				// in-place edit of a hot key doesn't double-count. A
+				// brand-new key (KVGet returns ErrKVNotFound) leaves
+				// delta untouched.
+				if existing, getErr := storage.KVGet(ctx, inv.SkillID, args.Scope, args.Key); getErr == nil && existing != nil {
+					delta -= int64(len(existing.Value))
+				} else if getErr != nil && !errors.Is(getErr, ErrKVNotFound) {
+					return "", fmt.Errorf("kv_set: pre-write lookup: %w", getErr)
+				}
+				if used+delta > kvMax {
+					return "", fmt.Errorf("kv_set: quota_exceeded — %d/%d bytes used; ask admin for higher quota", used, kvMax)
+				}
+			}
+
+			now := time.Now()
+			entry := KVDomainEntry{
+				SkillID:   partition,
+				Scope:     args.Scope,
+				Key:       args.Key,
+				Value:     args.Value,
+				CreatedAt: now,
+				UpdatedAt: now,
+			}
+			if args.TTLSeconds != nil && *args.TTLSeconds > 0 {
+				expires := now.Add(time.Duration(*args.TTLSeconds) * time.Second)
+				entry.ExpiresAt = &expires
+			}
+
+			if err := storage.KVSet(ctx, entry); err != nil {
+				return "", fmt.Errorf("kv_set: %w", err)
+			}
+			// V7 versioned KV history (admin diagnostic). Best-effort —
+			// a failed history write must NOT shadow the successful
+			// kv_set return, so we ignore the error after logging.
+			// Production adapter satisfies KVHistoryRecorder; tests
+			// using a bare KVStorage skip this branch entirely.
+			if h, ok := storage.(KVHistoryRecorder); ok && h != nil {
+				_ = h.RecordKVHistory(ctx, partition, args.Scope, args.Key, []byte(args.Value), inv.CallerID)
+			}
+			return "ok", nil
+		},
+	)
+}

tools/kv_storage.go

@@ -0,0 +1,89 @@
+// kv_storage.go declares the narrow KV-storage interface that the four
+// KV tools (kv_get, kv_set, kv_list, kv_delete) need at execute time.
+//
+// Why a narrow interface (vs importing pkg/logic/skills directly):
+// pkg/logic/skills imports pkg/skilltools (for Invocation + Tool), so
+// importing skills back here would form an import cycle. Production
+// wiring (pkg/logic/mort.go, deferred) will supply a concrete adapter
+// that wraps `*skills.System.Storage()` and translates between
+// skills.KVEntry and the local KVDomainEntry shape.
+//
+// Why a *separate* domain shape (KVDomainEntry) vs reusing skills.KVEntry:
+// the cycle break has to be complete — even importing the type would
+// pull skills into skilltools/tools' import graph. The two shapes mirror
+// each other field-for-field; the adapter is a trivial struct copy.
+//
+// The same pattern is used by skill_invoke.go (SkillInvokerProvider).
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"strings"
+	"time"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+// kvPartition picks the skill_id partition for a KV operation. KV rows
+// are keyed (skill_id, scope, key); for the shared `root_run:<id>`
+// scope, every run in a dispatch tree — including ephemeral workers
+// with distinct agent IDs — must land in ONE partition or siblings
+// could never see each other's writes. The sentinel
+// tool.RootRunKVPartition is that shared partition; isolation
+// between trees is preserved because the scope string embeds the root
+// run id, which ValidateScope checks against inv.RootRunID.
+func kvPartition(inv tool.Invocation, scope string) string {
+	if strings.HasPrefix(scope, "root_run:") {
+		return tool.RootRunKVPartition
+	}
+	return inv.SkillID
+}
+
+// KVStorage is the narrow surface KV tools need from the skills package.
+// nil-safe: tools constructed against a nil KVStorage surface a clean
+// "not configured" error at the first call rather than crashing.
+type KVStorage interface {
+	KVGet(ctx context.Context, skillID, scope, key string) (*KVDomainEntry, error)
+	KVSet(ctx context.Context, e KVDomainEntry) error
+	KVList(ctx context.Context, skillID, scope, prefix string, limit int) ([]KVDomainEntry, error)
+	KVDelete(ctx context.Context, skillID, scope, key string) error
+	KVUsageBytes(ctx context.Context, skillID string) (int64, error)
+}
+
+// KVHistoryRecorder is the OPTIONAL post-write hook for the v7
+// versioned KV history. The kv_set tool checks for this interface via
+// type assertion; production storage adapters that satisfy it write a
+// history row AFTER a successful KVSet.
+//
+// Why optional (vs adding to KVStorage): existing test fakes don't
+// need to grow a method. Production wires the real adapter which
+// satisfies the interface; tests that don't care about history skip
+// the implementation entirely.
+//
+// Why only on success: a failed KVSet leaves no skill_kv row to refer
+// to; appending a history entry would create an orphan record of a
+// change that didn't happen.
+type KVHistoryRecorder interface {
+	RecordKVHistory(ctx context.Context, skillID, scope, key string, value []byte, changedBy string) error
+}
+
+// KVDomainEntry mirrors skills.KVEntry without pulling in the cycle.
+// Field-for-field with the skills package's KVEntry; the production
+// adapter is a struct copy.
+type KVDomainEntry struct {
+	SkillID   string
+	Scope     string // "skill" | "user:<id>" | "run:<id>"
+	Key       string
+	Value     json.RawMessage
+	ExpiresAt *time.Time
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// ErrKVNotFound mirrors skills.ErrKVNotFound. The production adapter
+// returns this sentinel when wrapping a skills.ErrKVNotFound; tools
+// detect it with errors.Is to surface "not_found" to the LLM rather
+// than a generic error.
+var ErrKVNotFound = errors.New("kv: not found")

tools/quota_provider.go

@@ -0,0 +1,32 @@
+// quota_provider.go declares the narrow QuotaProvider interface used by
+// kv_set and file_save to enforce per-skill byte quotas at write time.
+//
+// Why a narrow interface (vs importing pkg/logic/skills directly): same
+// cycle constraint as kv_storage.go and file_storage.go — pkg/logic/skills
+// already imports pkg/skilltools, so importing skills back here would
+// form an import cycle. Production wiring (pkg/logic/mort.go) supplies
+// *skills.System, which satisfies QuotaProvider via its EffectiveQuota
+// method.
+//
+// Why a separate interface vs adding the method to KVStorage/FileStorage:
+// quota resolution is a system-level policy (combining override + convar
+// + default), not a pure storage read. Keeping it separate lets a tool
+// constructor accept a nil QuotaProvider when an integrator wants to
+// skip enforcement (e.g. an admin-only skill that bypasses caps).
+package tools
+
+import "context"
+
+// QuotaProvider returns effective per-skill quotas for the storage
+// tools' write-path enforcement. Production wires *skills.System, which
+// satisfies this via its EffectiveQuota method.
+//
+// nil-safe: tools constructed against a nil QuotaProvider do NOT enforce
+// per-skill quotas. That mode is useful for tests and for environments
+// where quota enforcement is intentionally disabled.
+type QuotaProvider interface {
+	// EffectiveQuota returns the effective KV and file byte caps for the
+	// skill. The two values resolve admin overrides + convar defaults +
+	// package constants in that order.
+	EffectiveQuota(ctx context.Context, skillID string) (kvMax, filesMax int64, err error)
+}

tools/store.go

@@ -0,0 +1,77 @@
+package tools
+
+import (
+	"context"
+	"errors"
+
+	"gitea.stevedudenhoeffer.com/steve/executus/tool"
+)
+
+// StoreDeps wires the persistent-memory tools (kv_* and file_*). A host
+// supplies its KV and/or File backends; the kv group registers only when KV is
+// set and the file group only when Files is set, so a host can take just one.
+// Everything else has a sensible default:
+//
+//   - Quota defaults to a generous static cap (a host that meters per-skill
+//     storage supplies its own QuotaProvider).
+//   - FileSearch / Minter+BaseURL are optional — file_search and
+//     create_file_url register only when wired.
+//   - MaxValueBytes / MaxFileBytes default when non-positive.
+type StoreDeps struct {
+	KV         KVStorage
+	Files      FileStorage
+	Quota      QuotaProvider
+	FileSearch FileSearcher
+	Minter     FileTokenMinter
+	BaseURL    string
+
+	MaxValueBytes int // kv_set per-value cap; default 256 KiB
+	MaxFileBytes  int // file_save per-file cap; default 16 MiB
+}
+
+// RegisterStore registers the kv_* tools (when KV is set) and the file_* tools
+// (when Files is set). At least one of KV/Files is required.
+func RegisterStore(reg tool.Registry, d StoreDeps) error {
+	if d.KV == nil && d.Files == nil {
+		return errors.New("tools: RegisterStore needs at least KV or Files")
+	}
+	if d.Quota == nil {
+		d.Quota = staticQuota{kvMax: 64 << 20, filesMax: 1 << 30}
+	}
+	if d.MaxValueBytes <= 0 {
+		d.MaxValueBytes = 256 << 10
+	}
+	if d.MaxFileBytes <= 0 {
+		d.MaxFileBytes = 16 << 20
+	}
+
+	var ts []tool.Tool
+	if d.KV != nil {
+		ts = append(ts,
+			NewKVGet(d.KV), NewKVSet(d.KV, d.Quota, d.MaxValueBytes),
+			NewKVList(d.KV), NewKVDelete(d.KV),
+		)
+	}
+	if d.Files != nil {
+		ts = append(ts,
+			NewFileSave(d.Files, d.Quota, d.MaxFileBytes),
+			NewFileGet(d.Files), NewFileGetText(d.Files), NewFileGetMetadata(d.Files),
+			NewFileList(d.Files), NewFileDelete(d.Files),
+		)
+		if d.FileSearch != nil {
+			ts = append(ts, NewFileSearch(d.FileSearch))
+		}
+		if d.Minter != nil && d.BaseURL != "" {
+			ts = append(ts, NewCreateFileURL(d.Minter, d.Files, d.BaseURL))
+		}
+	}
+	return registerAll(reg, ts...)
+}
+
+// staticQuota is the default QuotaProvider: a fixed KV/file byte cap for every
+// skill. A host that needs per-skill metering supplies its own.
+type staticQuota struct{ kvMax, filesMax int64 }
+
+func (q staticQuota) EffectiveQuota(context.Context, string) (kvMax, filesMax int64, err error) {
+	return q.kvMax, q.filesMax, nil
+}