fix(slides): local XML precheck, 99991400 backoff, quota code registration

Lands the four agreed fixes from the 2026-06-08 slides write-path
telemetry analysis:

1. Local XML well-formedness precheck (shortcuts/slides/)
   - checkXMLWellFormed: pure syntax validation via stdlib encoding/xml
     (same parser family as the backend, false-positive risk ~0);
     explicitly rejects <?xml ?> declarations; deliberately allows
     multiple top-level elements (legal in block_insert fragments)
   - wired into +create --slides (at Validate, so a bad slide no longer
     leaves a half-built deck) and +replace-slide --parts
     replacement/insertion; errors carry line numbers + escaping
     guidance, rejected locally with zero API calls

2. 99991400 rate-limit backoff (retryOnRateLimit)
   - the code was registered Retryable:true but no slides loop actually
     retried, so one frequency-window hit aborted the whole batch
   - up to 2 retries with 1s/2s backoff, announced on stderr,
     context-cancellable; wired into the +create slide POST loop and
     uploadSlidesMedia (+media-upload and the placeholder upload loop)
   - upload switched to UploadDriveMediaAllTyped (retry match requires
     typed errors; aligns with the slides typed migration)

3. Quota codes 90003086/87/88 registered (internal/errclass + output)
   - cloud-space explorer billing codes passed through as HTTP 200 with
     body code!=0; previously fell to SubtypeUnknown
   - now CategoryAPI + quota_exceeded, not retryable, with per-code
     hints (upgrade plan / free quota / ask admin to enable the module)

4. lark-slides skill tag-whitelist ban (skills/lark-slides/)
   - quick-ref: never write tags outside the whitelist, name the six
     confirmed-rejected tags (audio/video/timeline/animation/trigger/
     header), substitution table, escaping rules
   - removed <?xml ?> declarations from all examples (contradicted
     backend behavior and the new precheck)

Tested with unit + httpmock integration tests, plus live verification
against the real feishu.cn API: all precheck negatives rejected locally,
no false positives on real create/replace, and 18 concurrent uploads hit
3 real 99991400 responses which all retried and succeeded (18/18).

Author: ViperCai

internal/errclass/classify.go

@@ -142,7 +142,13 @@ func BuildAPIError(resp map[string]any, cc ClassifyContext) error {
 		}
 	case errs.CategoryAPI:
 		// A server-supplied detail (lifted into base.Hint above) wins over the
-		// context-free APIHint default; only fall back to APIHint when absent.
+		// context-free defaults; below that, a per-code CodeMeta.Hint (for codes
+		// whose recovery is more specific than their subtype's wording) wins
+		// over the per-subtype APIHint; only fall back to APIHint when both
+		// are absent.
+		if base.Hint == "" {
+			base.Hint = meta.Hint
+		}
 		if base.Hint == "" {
 			base.Hint = APIHint(base.Subtype) // "" for subtypes without a context-free default
 		}

internal/errclass/classify_test.go

@@ -173,6 +173,54 @@ func TestBuildAPIError_TaskInvalidParamsRoutesToAPIError(t *testing.T) {
 	}
 }
 
+// TestBuildAPIError_PerCodeHint pins that the CategoryAPI arm surfaces the
+// per-code CodeMeta.Hint on the typed envelope — the commercial-plan codes
+// are produced by typed call sites (slides +create, drive import), so without
+// this the plan-quota codes would inherit the misleading per-subtype default
+// ("retry after the relevant quota resets") and 90003088 would carry no hint
+// at all. Also pins precedence: a server-supplied detail still wins.
+func TestBuildAPIError_PerCodeHint(t *testing.T) {
+	t.Run("quota code gets per-code hint over subtype default", func(t *testing.T) {
+		resp := map[string]any{"code": 90003087, "msg": "A2 create quota exceeded"}
+		err := errclass.BuildAPIError(resp, errclass.ClassifyContext{})
+		p, ok := errs.ProblemOf(err)
+		if !ok {
+			t.Fatal("ProblemOf returned !ok")
+		}
+		if !strings.Contains(p.Hint, "retrying will not help") {
+			t.Errorf("Hint = %q, want the per-code plan-quota hint, not the generic quota-resets default", p.Hint)
+		}
+	})
+	t.Run("failed-precondition code gets per-code hint despite empty subtype default", func(t *testing.T) {
+		resp := map[string]any{"code": 90003088, "msg": "docs module unbundled"}
+		err := errclass.BuildAPIError(resp, errclass.ClassifyContext{})
+		p, ok := errs.ProblemOf(err)
+		if !ok {
+			t.Fatal("ProblemOf returned !ok")
+		}
+		if !strings.Contains(p.Hint, "docs module") {
+			t.Errorf("Hint = %q, want the per-code docs-module hint", p.Hint)
+		}
+	})
+	t.Run("server detail still wins over per-code hint", func(t *testing.T) {
+		resp := map[string]any{
+			"code": 90003087,
+			"msg":  "A2 create quota exceeded",
+			"error": map[string]any{
+				"details": []any{map[string]any{"value": "server-side specifics"}},
+			},
+		}
+		err := errclass.BuildAPIError(resp, errclass.ClassifyContext{})
+		p, ok := errs.ProblemOf(err)
+		if !ok {
+			t.Fatal("ProblemOf returned !ok")
+		}
+		if !strings.Contains(p.Hint, "server-side specifics") {
+			t.Errorf("Hint = %q, want lifted server detail to take precedence", p.Hint)
+		}
+	})
+}
+
 // TestBuildAPIError_TroubleshooterLiftedOnAPIArm pins that BuildAPIError lifts
 // resp.error.troubleshooter into Problem.Troubleshooter when the response
 // routes to the catch-all CategoryAPI arm. troubleshooter is the only

internal/errclass/codemeta.go

@@ -10,16 +10,25 @@ import (
 )
 
 // CodeMeta is the classification metadata attached to a Lark numeric code.
-// It does NOT carry Message or Hint — those are derived at the dispatcher
+// It does NOT carry Message — that is derived at the dispatcher
 // (see BuildAPIError).
 //
+// Hint is the optional per-code context-free recovery hint for codes whose
+// recovery action is more specific than their subtype's APIHint default
+// (e.g. a plan-quota code whose quota never resets, so the generic
+// "retry after the quota resets" wording would mislead). The CategoryAPI
+// dispatcher arm prefers a server-supplied detail, then this per-code hint,
+// then APIHint(subtype). Leave empty when the subtype default (or no hint)
+// is accurate.
+//
 // Risk + Action are populated only for codes that route to CategoryConfirmation;
 // the dispatcher falls back to RiskUnknown + ctx.LarkCmd when either is empty
 // so the envelope is never wire-invalid.
 type CodeMeta struct {
 	Category  errs.Category
 	Subtype   errs.Subtype
 	Retryable bool
+	Hint      string // CategoryAPI arm only; empty → fall back to APIHint(subtype)
 	Risk      string // CategoryConfirmation arm only; empty otherwise
 	Action    string // CategoryConfirmation arm only; empty otherwise
 }

internal/errclass/codemeta_drive.go

@@ -12,6 +12,26 @@ import "github.com/larksuite/cli/errs"
 var driveCodeMeta = map[int]CodeMeta{
 	1061044: {Category: errs.CategoryAPI, Subtype: errs.SubtypeNotFound},          // parent folder does not exist (upload)
 	1069302: {Category: errs.CategoryAPI, Subtype: errs.SubtypeInvalidParameters}, // comment endpoint "Invalid or missing parameters"
+
+	// Commercial plan codes returned by the cloud-space explorer service
+	// and passed through verbatim by document backends (observed via
+	// slides_ai create — engine log "A2 create quota exceeded, code=90003087"
+	// — and drive/v1/import_tasks, both as HTTP 200 with body code≠0).
+	// Plan/billing limits: retrying can never succeed. 90003086/90003087 are
+	// plan creation-count quotas (upgrade the plan or free quota); 90003088 is
+	// not a quota at all — the tenant has not purchased/enabled the docs
+	// module, so it maps to FailedPrecondition (admin must enable the module)
+	// rather than QuotaExceeded, whose default hint suggests freeing quota.
+	// Hint is set per-code because the SubtypeQuotaExceeded default
+	// ("retry after the relevant quota resets") misleads here: plan quotas
+	// never reset on their own. Keep the wording in sync with the legacy
+	// path's legacyHints entries (internal/output/lark_errors.go).
+	90003086: {Category: errs.CategoryAPI, Subtype: errs.SubtypeQuotaExceeded,
+		Hint: "document creation quota of the current plan reached: upgrade the plan or delete documents you no longer need to free quota; retrying will not help"}, // premium plan creation count limit reached
+	90003087: {Category: errs.CategoryAPI, Subtype: errs.SubtypeQuotaExceeded,
+		Hint: "document creation quota of the current plan reached: upgrade the plan or delete documents you no longer need to free quota; retrying will not help"}, // A2 plan creation count limit reached
+	90003088: {Category: errs.CategoryAPI, Subtype: errs.SubtypeFailedPrecondition,
+		Hint: "the tenant has not purchased or enabled the docs module; ask the tenant admin to enable it before creating documents"}, // unbundle: tenant has not purchased / been granted the docs module
 }
 
 func init() { mergeCodeMeta(driveCodeMeta, "drive") }

internal/errclass/codemeta_drive_test.go

@@ -27,6 +27,14 @@ func TestLookupCodeMeta_DriveCodes(t *testing.T) {
 		// 1069302: comment endpoint's opaque "Invalid or missing parameters"
 		// (shortcuts/drive/drive_add_comment.go) → API-side parameter rejection.
 		{1069302, errs.CategoryAPI, errs.SubtypeInvalidParameters, false},
+		// 9000308x: cloud-space explorer commercial plan codes, passed
+		// through by document backends (slides_ai create, drive import_tasks)
+		// as HTTP 200 with body code≠0. Billing limits → never retryable.
+		// 86/87 are plan creation-count quotas; 88 is "docs module not
+		// purchased/enabled" — a precondition, not a quota.
+		{90003086, errs.CategoryAPI, errs.SubtypeQuotaExceeded, false},
+		{90003087, errs.CategoryAPI, errs.SubtypeQuotaExceeded, false},
+		{90003088, errs.CategoryAPI, errs.SubtypeFailedPrecondition, false},
 	}
 	for _, tc := range cases {
 		t.Run(fmt.Sprintf("%d", tc.code), func(t *testing.T) {

internal/output/lark_errors.go

@@ -84,6 +84,14 @@ const (
 	LarkErrMailSendQuotaTenantExt = 1236009 // tenant daily external recipient count exceeded
 	LarkErrMailQuota              = 1236010 // mail quota limit
 	LarkErrTenantStorageLimit     = 1236013 // tenant storage limit exceeded
+
+	// Docs/slides commercial plan quota codes from the cloud-space explorer
+	// service, passed through verbatim by document backends as HTTP 200 with
+	// body code≠0 (observed on slides_ai create and drive/v1/import_tasks).
+	// Not retryable: these are billing-plan limits.
+	LarkErrDocsCreatePremiumQuota = 90003086 // premium plan document creation count limit reached
+	LarkErrDocsCreateA2Quota      = 90003087 // A2 plan document creation count limit reached
+	LarkErrDocsModuleUnbundled    = 90003088 // tenant has not purchased / enabled the docs module
 )
 
 // legacyHints supplies the per-code actionable hint string for the legacy
@@ -118,6 +126,10 @@ var legacyHints = map[int]string{
 		"width/height must be >= 20 px; offsets must be >= 0 and less than the anchor cell's width/height",
 	LarkErrDrivePermApplyRateLimit:     "permission-apply quota reached: each user may request access on the same document at most 5 times per day; wait or ask the owner directly",
 	LarkErrDrivePermApplyNotApplicable: "this document does not accept a permission-apply request (common causes: the document is configured to disallow access requests, the caller already holds the permission, or the target type does not support apply); contact the owner directly",
+
+	LarkErrDocsCreatePremiumQuota: "document creation quota of the current plan reached: upgrade the plan or delete documents you no longer need to free quota; retrying will not help",
+	LarkErrDocsCreateA2Quota:      "document creation quota of the current plan reached: upgrade the plan or delete documents you no longer need to free quota; retrying will not help",
+	LarkErrDocsModuleUnbundled:    "the tenant has not purchased or enabled the docs module; ask the tenant admin to enable it before creating documents",
 }
 
 // ClassifyLarkError maps a Lark API error code + message to the legacy

shortcuts/slides/helpers.go

@@ -4,15 +4,73 @@
 package slides
 
 import (
+	"context"
+	"encoding/xml"
 	"fmt"
+	"io"
 	"net/url"
 	"regexp"
 	"strings"
+	"time"
 
 	"github.com/larksuite/cli/errs"
 	"github.com/larksuite/cli/shortcuts/common"
 )
 
+const (
+	// slidesRateLimitMaxRetries is the number of automatic retries (beyond the
+	// initial request) when the API answers 99991400 "request trigger frequency
+	// limit". The slides batch paths (+create slide loop, placeholder image
+	// uploads) fire consecutive POSTs and are the dominant 99991400 producers
+	// in telemetry; a short backoff absorbs the per-second window without
+	// masking a genuinely saturated tenant.
+	slidesRateLimitMaxRetries = 2
+)
+
+// slidesRateLimitBaseDelay is the initial backoff delay; subsequent retries
+// double it (1s, 2s). Mirrors the wiki +node-create lock-contention pattern
+// but with a larger base because frequency limits are per-second windows, not
+// sub-second lock races. var (not const) only so tests can shrink it.
+var slidesRateLimitBaseDelay = 1 * time.Second
+
+// isRateLimitedErr reports whether err is a typed retryable rate-limit error
+// (e.g. 99991400), as classified by errclass.BuildAPIError.
+func isRateLimitedErr(err error) bool {
+	p, ok := errs.ProblemOf(err)
+	return ok && p.Subtype == errs.SubtypeRateLimit && p.Retryable
+}
+
+// retryOnRateLimit runs fn, retrying with exponential backoff (1s, 2s) when it
+// returns a retryable rate-limit error. Any other outcome — success or a
+// different error — is returned immediately. Progress is announced on errOut
+// so a user watching a batch upload understands the pause.
+func retryOnRateLimit(ctx context.Context, errOut io.Writer, fn func() error) error {
+	var lastErr error
+	for attempt := 0; attempt <= slidesRateLimitMaxRetries; attempt++ {
+		if attempt > 0 {
+			delay := slidesRateLimitBaseDelay << uint(attempt-1)
+			// Report the actual code from the error: the retry predicate matches
+			// any retryable SubtypeRateLimit, not just 99991400.
+			code := 0
+			if p, ok := errs.ProblemOf(lastErr); ok {
+				code = p.Code
+			}
+			fmt.Fprintf(errOut, "Rate limited by the API (%d), retrying (attempt %d/%d) in %v...\n",
+				code, attempt, slidesRateLimitMaxRetries, delay)
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case <-time.After(delay):
+			}
+		}
+		lastErr = fn()
+		if lastErr == nil || !isRateLimitedErr(lastErr) {
+			return lastErr
+		}
+	}
+	return lastErr
+}
+
 // presentationRef holds a parsed --presentation input.
 //
 // Slides shortcuts accept three input shapes:
@@ -125,8 +183,30 @@ func resolvePresentationID(runtime *common.RuntimeContext, ref presentationRef)
 // around `=`); without it we'd silently leave such placeholders unrewritten.
 var imgSrcPlaceholderRegex = regexp.MustCompile(`(?s)<img\b[^>]*?\bsrc\s*=\s*(["'])@([^"']+)(["'])`)
 
+// xmlEntityUnescaper reverses the five XML built-in entities in attribute
+// values captured from raw slide XML. strings.Replacer scans left-to-right in
+// a single pass, so "&amp;lt;" correctly yields "&lt;" (the leading "&amp;"
+// is consumed first), matching XML unescape semantics.
+var xmlEntityUnescaper = strings.NewReplacer(
+	"&lt;", "<",
+	"&gt;", ">",
+	"&quot;", `"`,
+	"&apos;", "'",
+	"&amp;", "&",
+)
+
+// placeholderFilePath converts a raw <img src="@..."> capture into the local
+// filesystem path it refers to. The capture comes from well-formed XML where
+// a literal & must be written &amp; (the precheck enforces this), so the
+// entities are decoded before the path touches Stat/upload. Filesystem paths
+// containing & are therefore written as e.g. src="@./Q1&amp;Q2.png".
+func placeholderFilePath(raw string) string {
+	return xmlEntityUnescaper.Replace(strings.TrimSpace(raw))
+}
+
 // extractImagePlaceholderPaths returns the de-duplicated list of local paths
-// referenced via <img src="@path"> in the given slide XML strings.
+// referenced via <img src="@path"> in the given slide XML strings, with XML
+// built-in entities decoded (see placeholderFilePath).
 //
 // Order is preserved (first occurrence wins) so dry-run / progress messages are
 // stable across runs.
@@ -141,7 +221,7 @@ func extractImagePlaceholderPaths(slideXMLs []string) []string {
 				// so we filter it here. Treat as malformed XML and skip.
 				continue
 			}
-			path := strings.TrimSpace(m[2])
+			path := placeholderFilePath(m[2])
 			if path == "" || seen[path] {
 				continue
 			}
@@ -280,6 +360,47 @@ func ensureShapeHasContent(xmlFragment string) string {
 	return xmlFragment[:m[1]] + "<content/>" + afterOpen
 }
 
+// checkXMLWellFormed verifies that fragment parses as well-formed XML, using
+// the same parser family as the backend (Go encoding/xml). Syntax only —
+// element names and attributes are NOT checked against the SML schema, so
+// anything passing here can still be rejected server-side for semantic
+// reasons; conversely nothing rejected here could ever have succeeded, which
+// keeps the false-positive risk at zero.
+//
+// The backend reports these failures as an opaque 3350001/4001000
+// "invalid param" with no position info; catching them locally turns the
+// dominant real-world causes (bare & in text, unclosed tags, attribute
+// quoting) into actionable messages with a line number.
+//
+// An <?xml ?> declaration is rejected explicitly: the rendering backend does
+// not accept processing instructions on slide fragments (rejects with
+// "?xml not provide the implement"). encoding/xml surfaces it as a regular
+// ProcInst token, so it needs its own check.
+//
+// Multiple top-level elements are deliberately allowed — insertion fragments
+// may legitimately carry sibling elements.
+func checkXMLWellFormed(fragment string) error {
+	dec := xml.NewDecoder(strings.NewReader(fragment))
+	for {
+		tok, err := dec.Token()
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			if syn, ok := err.(*xml.SyntaxError); ok {
+				return errs.NewValidationError(errs.SubtypeInvalidArgument,
+					"XML not well-formed at line %d: %s (escape literal & as &amp; and < as &lt; in text)",
+					syn.Line, syn.Msg)
+			}
+			return errs.NewValidationError(errs.SubtypeInvalidArgument, "XML not well-formed: %v", err)
+		}
+		if pi, ok := tok.(xml.ProcInst); ok && strings.EqualFold(pi.Target, "xml") {
+			return errs.NewValidationError(errs.SubtypeInvalidArgument,
+				"XML must not contain an <?xml ?> declaration (the slides backend rejects it); remove it and start at the root element")
+		}
+	}
+}
+
 // replaceImagePlaceholders rewrites <img src="@path"> occurrences in the input
 // XML by looking up each path in tokens. Paths missing from the map are left
 // untouched (callers should ensure the map is complete).
@@ -294,7 +415,10 @@ func replaceImagePlaceholders(slideXML string, tokens map[string]string) string
 			// Mismatched quotes — see extractImagePlaceholderPaths.
 			return match
 		}
-		token, ok := tokens[strings.TrimSpace(path)]
+		// tokens is keyed by the decoded filesystem path (see
+		// extractImagePlaceholderPaths), while oldQuoted below must use the
+		// raw capture so the literal XML text is what gets replaced.
+		token, ok := tokens[placeholderFilePath(path)]
 		if !ok {
 			return match
 		}