fix(mcpl): malformed MCPL blocks and failed Discord attachment fetches are shown, not dropped

changelog.d/fix-silent-drops-say-so.fixed.md

@@ -0,0 +1,3 @@
+- An MCPL text block whose text isn't a string, which only a nonconformant server sends, now reaches the agent as `[Text not shown: the server's text block had no string text.]` instead of vanishing from its view or reading as `[object Object]`. That holds on the push and channel lanes, coalesced or not, in a `context/beforeInference` injection, and in a tool result, text-only or beside an image or a reference, where such a block sent the whole result to the agent as JSON, a reference's uri included. An MCPL tool error whose only text isn't a string now reports the placeholder as its error, where it read `[object Object]` for an object, the value itself for a number or `true`, its items joined by commas for an array, and `Tool call failed` for `null`, `false` or `0`. A `system` injection's text used to be joined into the system prompt as it was, which for an object with no string form threw while the request was built; a text-only tool result whose only block was such a text came back as an empty success. The placeholder still counts as no text when a message is checked for visible content, so a message holding only such blocks (or blank text) is still refused as empty, with the same answers as before, and a message whose blocks are numbers, strings or booleans is still admitted uncoalesced as its untyped placeholders. A `shouldTriggerInference` filter, and so the EventGate's content filter, now reads the placeholder where it read an empty line, as it already reads the converters' other placeholders.
+- A `context/beforeInference` injection's content now converts as a pushed event's and a channel message's does: one converter serves all three. Before, an injection block whose `type` wasn't a string read as that value (`[unrecognized content block: 5]`, `[unrecognized content block: [object Object]]`), and one whose `type` was an object with no string form threw while it was converted, so the framework dropped every server's injections for that turn, with only a console line. An image's `data`, `mimeType` or `uri`, or an audio block's `data` or `mimeType`, that wasn't a string was passed on to the provider as the block's source, and a `uri` with a `disposition` was taken as a reference. An audio block without inline data showed its uri in its text: one that wasn't a string read as itself, and one with no string form threw, as a `type` did. Such fields now count as absent, and such blocks show the placeholders the other lanes show: `[unrecognized content block: untyped]`; `[Image: no data]` (where it read `[Image: missing data]`) or `[Image: no media type]`; and `[Audio: no data]` (where it read `[Audio: <uri>]` or `[Audio: missing data]`) or `[Audio: no media type]`. So an injection no longer writes an audio block's uri into the agent's text. An injection the host can't read is now left out with a console line naming its server, and the turn keeps every other injection: one holding a null block or content that isn't an array, a null injection, or one whose position has no string form, and likewise an answer whose injections aren't a list. Before, any of these dropped them all. An injection whose namespace can't be read as text, such as `{"toString": 1}`, is left out the same way. Before, a `beforeUser` or `afterUser` one failed the whole request, since context-manager writes the namespace into a participant's name as it builds the request, and a `system` one arrived, as context-manager never reads its namespace. Any other namespace that isn't a string, which §10.4 doesn't allow, still reaches the agent as it did: a `beforeUser` or `afterUser` injection's is written into its participant's name as its text, such as `system_context:5`, or `system_context:undefined` for an injection without one. The first such namespace from each server now gets a console line saying so. The line for an injection outside the server's grant now prints its position as one field, so a position holding a line break can't add a line of its own.
+- The Discord module now gives the agent `[Attachment: <filename> (failed to fetch)]` for a text attachment whose download is answered with a status that isn't OK, as it already did when the download threw. Before, such an attachment was left out without a word, and a message with nothing else in it read `[Empty message]`. Either failure now also writes a console line naming the file, the message and the status or error, and an answer that isn't OK has its body cancelled, so its connection is released.

src/framework.ts

@@ -74,14 +74,15 @@ import { HookOrchestrator } from './mcpl/hook-orchestrator.js';
 import { ToolLifecycleEmitter, parseToolObserveParams, type ScriptCallOrigin } from './mcpl/tool-lifecycle.js';
 import { checkToolPattern, describeUnmatchedPattern, type PatternServer } from './mcpl/tool-pattern-check.js';
 import { BUILTIN_TOOL_CLASSES, normalizeClassTable, parseDeclaredClasses, resolveToolClass, type EffectiveToolClass, type ToolClass, type ToolClassSource } from './mcpl/tool-classes.js';
-import { PushHandler, convertBlock as convertPushBlock, type McplPushEvent } from './mcpl/push-handler.js';
+import { PushHandler, type McplPushEvent } from './mcpl/push-handler.js';
+import { convertBlock } from './mcpl/convert-block.js';
 import {
   PushCoalescer, CoalesceError, PUSH_COALESCING_SUPPORT, validateCoalesceMember, validateCoalescedContent,
   coalescingSubjectKey, type AssemblyResult, type CoalescedOccurrence, type CoalescingPlacement, type CoalescingSnapshot,
   type CoalescingReceiptRecord,
 } from './mcpl/push-coalescer.js';
 import type { ChannelIncomingMessage, ChannelIncomingMessageResult, McplContentBlock, PushEventResult } from './mcpl/types.js';
-import { isSilentHeartbeatMarker, isVisiblyEmptyContent } from './mcpl/visible-content.js';
+import { isSilentHeartbeatMarker, isVisiblyEmptyContent, NON_STRING_TEXT_PLACEHOLDER } from './mcpl/visible-content.js';
 import { parseProsePrefix, parseHybridProsePrefix } from './mcpl/prose-grammar.js';
 import { ProseStreamRouter } from './mcpl/prose-stream-router.js';
 import { detectKnownToolWrapperProse } from './tool-wrapper-prose-guard.js';
@@ -9875,7 +9876,7 @@ export class AgentFramework {
         messageId: identity.messageId ?? str(origin.messageId) ?? occ.eventId,
         threadId: identity.threadId ?? str(origin.threadId),
         author: identity.author ?? { id: str(origin.authorId) ?? '', name: str(origin.authorName) ?? str(origin.authorId) ?? 'Someone' },
-        content: materialized ? materialized.map(convertPushBlock) : push.content,
+        content: materialized ? materialized.map((block) => convertBlock(block, 'attachment on push event')) : push.content,
         timestamp: occ.timestamp,
         metadata: origin,
         tags: push.tags,
@@ -9894,7 +9895,7 @@ export class AgentFramework {
       ...occ.event.event,
       eventId: occ.eventId,
       timestamp: occ.timestamp,
-      ...(materialized ? { content: materialized.map(convertPushBlock) } : {}),
+      ...(materialized ? { content: materialized.map((block) => convertBlock(block, 'attachment on push event')) } : {}),
       coalescingSubject,
       // §5.2: the materialized occurrence is consumed by the request being
       // assembled; the wake that started it is not repeated.
@@ -14590,8 +14591,10 @@ export class AgentFramework {
         blocks.push({ type: 'text', text: INLINE_WITHHELD_TEXT });
         continue;
       }
-      if (b.type === 'text' && typeof b.text === 'string') {
-        let text = b.text;
+      if (b.type === 'text') {
+        // A text that isn't a string shows as the converters' placeholder,
+        // rather than sending the whole array to the JSON fallback.
+        let text = typeof b.text === 'string' ? b.text : NON_STRING_TEXT_PLACEHOLDER;
         if (maxChars && text.length > maxChars) {
           text = safeSlice(text, 0, maxChars)
             + '\n\n[truncated — original was ' + text.length + ' chars'
@@ -17944,9 +17947,13 @@ export class AgentFramework {
         // through so toMembraneToolResult can preserve image blocks natively.
         // Text-only results still collapse to a joined string for backward
         // compatibility with callers that expect data to be string-ish.
+        // A text block whose text isn't a string, which only a nonconformant
+        // server sends, shows as the converter's placeholder, where it used to
+        // vanish (null, 0, false) or read as String(text), "[object Object]".
         const textContent = result.content
-          ?.filter((c) => c.type === 'text' && c.text)
-          .map((c) => c.text!)
+          ?.filter((c) => c.type === 'text')
+          .map((c) => (typeof c.text === 'string' ? c.text : NON_STRING_TEXT_PLACEHOLDER))
+          .filter((text) => text !== '')
           .join('\n');
         const hasNonText = result.content?.some((c) => c.type !== 'text');
         const data = result.isError

src/mcpl/channel-registry.ts

@@ -14,7 +14,7 @@
  */
 
 import type { ContentBlock } from '@animalabs/membrane';
-import { INLINE_WITHHELD_TEXT, isInlineContradiction, referenceStubOrNull } from './references.js';
+import { convertBlock } from './convert-block.js';
 import type { JsStore } from '@animalabs/chronicle';
 
 import type {
@@ -30,15 +30,14 @@ import type {
   ChannelsPublishParams,
   ChannelsOpenResult,
   ChannelHistoryRequest,
-  McplContentBlock,
 } from './types.js';
 
 import type { McplServerRegistry } from './server-registry.js';
 import type { FeatureSetManager } from './feature-set-manager.js';
 import type { ToolDefinition, ToolResult, ProcessEvent } from '../types/index.js';
 import { expandCoreTags } from './tags.js';
 import { coalesceRejectionReason, EmptyContentError, validateCoalescedContent } from './push-coalescer.js';
-import { isVisiblyEmptyContent } from './visible-content.js';
+import { isVisiblyEmptyConversion } from './visible-content.js';
 import { logDetail, logValue } from './log-value.js';
 import { RefusalLines } from './refusal-lines.js';
 import { CapabilityGrant } from './capability-grant.js';
@@ -241,88 +240,6 @@ interface McplChannelIncomingEvent {
   targetAgents?: string[];
 }
 
-// ============================================================================
-// Content Conversion: McplContentBlock → membrane ContentBlock
-// ============================================================================
-
-/**
- * Convert a single MCPL wire-format content block to a membrane ContentBlock.
- */
-function convertBlock(block: McplContentBlock): ContentBlock {
-  switch (block.type) {
-    case 'text':
-      // Text that isn't a string is no text, as the request sanitizer and
-      // the visible-content check already read it.
-      return { type: 'text', text: typeof block.text === 'string' ? block.text : '' };
-
-    case 'image':
-      if (isInlineContradiction(block)) {
-        // RFC-005 vector 2: inline data claiming bulk disposition — fail
-        // closed, withhold the data (checked BEFORE the data branch).
-        return { type: 'text', text: INLINE_WITHHELD_TEXT };
-      }
-      if (isFilledString(block.uri) && block.disposition) {
-        // RFC-005 uri-form media with a disposition claim: stub, do not
-        // hand the URI to the provider or inline it.
-        return { type: 'text', text: referenceStubOrNull(block, 'attachment on channel message') ?? '[reference]' };
-      }
-      if (isFilledString(block.data) && isFilledString(block.mimeType)) {
-        return {
-          type: 'image',
-          source: { type: 'base64', data: block.data, mediaType: block.mimeType },
-        } as ContentBlock;
-      }
-      if (isFilledString(block.uri)) {
-        return {
-          type: 'image',
-          source: { type: 'url', url: block.uri },
-        } as ContentBlock;
-      }
-      return { type: 'text', text: isFilledString(block.data) ? '[Image: no media type]' : '[Image: no data]' };
-
-    case 'audio':
-      if (isInlineContradiction(block)) {
-        // RFC-005 vector 2: inline data claiming bulk disposition — fail
-        // closed, withhold the data (checked BEFORE the data branch).
-        return { type: 'text', text: INLINE_WITHHELD_TEXT };
-      }
-      if (isFilledString(block.uri) && block.disposition) {
-        // RFC-005 uri-form media with a disposition claim: stub, do not
-        // hand the URI to the provider or inline it.
-        return { type: 'text', text: referenceStubOrNull(block, 'attachment on channel message') ?? '[reference]' };
-      }
-      if (isFilledString(block.data) && isFilledString(block.mimeType)) {
-        return {
-          type: 'audio',
-          source: { type: 'base64', data: block.data, mediaType: block.mimeType },
-        } as ContentBlock;
-      }
-      return { type: 'text', text: isFilledString(block.data) ? '[Audio: no media type]' : '[Audio: no data]' };
-
-    case 'resource':
-      // RFC-005: reference blocks become bounded stubs — never raw URIs
-      // (a signed URL is a bearer credential that looks like a location).
-      return { type: 'text', text: referenceStubOrNull(block, 'attachment on channel message') ?? '[reference]' };
-
-    default: {
-      // Unknown wire block types previously fell off the exhaustive switch
-      // and propagated `undefined` into ContentBlock[]. Fail visibly. A type
-      // that isn't a string is no type, and is never converted to one: an
-      // object can throw when it is.
-      const type: unknown = (block as { type?: unknown }).type;
-      return { type: 'text', text: `[unrecognized content block: ${typeof type === 'string' ? type : 'untyped'}]` };
-    }
-  }
-}
-
-/** A string with something in it: the only data, mimeType or uri a block's
- *  source is built from, and the only uri that makes it a reference. Anything
- *  else a sender puts there leaves the block without it, so conversion never
- *  throws and never copies a non-string. */
-function isFilledString(value: unknown): value is string {
-  return typeof value === 'string' && value !== '';
-}
-
 // ============================================================================
 // Channel Tool Definitions
 // ============================================================================
@@ -1031,8 +948,8 @@ export class ChannelRegistry {
         }
       }
       if (message.tags) message.tags = expandCoreTags(message.tags);
-      const convertedContent: ContentBlock[] = message.content.map(convertBlock);
-      if (!emptyAllowed && isVisiblyEmptyContent(convertedContent)) {
+      const convertedContent: ContentBlock[] = message.content.map((block) => convertBlock(block, 'attachment on channel message'));
+      if (!emptyAllowed && isVisiblyEmptyConversion(message.content, convertedContent)) {
         rejectEmpty();
         continue;
       }
@@ -1060,7 +977,7 @@ export class ChannelRegistry {
       if (this.shouldTriggerInference) {
         // The text the agent's context gets, as the push lane's filter reads
         // it: the converted text blocks, a placeholder or reference stub
-        // among them, and a text block's non-string text as empty text.
+        // among them, NON_STRING_TEXT_PLACEHOLDER included.
         const textContent = convertedContent
           .filter((b): b is ContentBlock & { type: 'text' } => b.type === 'text')
           .map((b) => b.text)

src/mcpl/convert-block.ts

@@ -0,0 +1,94 @@
+/**
+ * MCPL wire content to membrane content: the one conversion every lane uses,
+ * for pushed events, channel messages and context injections alike, so a rule
+ * about a malformed block holds on all three.
+ */
+
+import type { ContentBlock } from '@animalabs/membrane';
+import { INLINE_WITHHELD_TEXT, isInlineContradiction, referenceStubOrNull } from './references.js';
+import { NON_STRING_TEXT_PLACEHOLDER } from './visible-content.js';
+import type { McplContentBlock } from './types.js';
+
+/**
+ * Convert a single MCPL wire-format content block to a membrane ContentBlock.
+ * It takes any block but null or undefined without throwing (those two throw,
+ * for the caller to refuse or leave out): a type, data, mimeType or uri that
+ * isn't a string counts as absent, and a text block whose text isn't a string
+ * shows as NON_STRING_TEXT_PLACEHOLDER. `provenance` is what a reference stub
+ * says the reference came on, such as 'attachment on push event'.
+ */
+export function convertBlock(block: McplContentBlock, provenance: string): ContentBlock {
+  switch (block.type) {
+    case 'text':
+      // Text that isn't a string can't be shown, so the agent reads that a
+      // block was there; the emptiness checks still count it as no text
+      // (isVisiblyEmptyConversion), as the request sanitizer would.
+      return { type: 'text', text: typeof block.text === 'string' ? block.text : NON_STRING_TEXT_PLACEHOLDER };
+
+    case 'image':
+      if (isInlineContradiction(block)) {
+        // RFC-005 vector 2: inline data claiming bulk disposition — fail
+        // closed, withhold the data (checked BEFORE the data branch).
+        return { type: 'text', text: INLINE_WITHHELD_TEXT };
+      }
+      if (isFilledString(block.uri) && block.disposition) {
+        // RFC-005 uri-form media with a disposition claim: stub, do not
+        // hand the URI to the provider or inline it.
+        return { type: 'text', text: referenceStubOrNull(block, provenance) ?? '[reference]' };
+      }
+      if (isFilledString(block.data) && isFilledString(block.mimeType)) {
+        return {
+          type: 'image',
+          source: { type: 'base64', data: block.data, mediaType: block.mimeType },
+        } as ContentBlock;
+      }
+      if (isFilledString(block.uri)) {
+        return {
+          type: 'image',
+          source: { type: 'url', url: block.uri },
+        } as ContentBlock;
+      }
+      return { type: 'text', text: isFilledString(block.data) ? '[Image: no media type]' : '[Image: no data]' };
+
+    case 'audio':
+      if (isInlineContradiction(block)) {
+        // RFC-005 vector 2: inline data claiming bulk disposition — fail
+        // closed, withhold the data (checked BEFORE the data branch).
+        return { type: 'text', text: INLINE_WITHHELD_TEXT };
+      }
+      if (isFilledString(block.uri) && block.disposition) {
+        // RFC-005 uri-form media with a disposition claim: stub, do not
+        // hand the URI to the provider or inline it.
+        return { type: 'text', text: referenceStubOrNull(block, provenance) ?? '[reference]' };
+      }
+      if (isFilledString(block.data) && isFilledString(block.mimeType)) {
+        return {
+          type: 'audio',
+          source: { type: 'base64', data: block.data, mediaType: block.mimeType },
+        } as ContentBlock;
+      }
+      return { type: 'text', text: isFilledString(block.data) ? '[Audio: no media type]' : '[Audio: no data]' };
+
+    case 'resource':
+      // RFC-005: reference blocks become bounded stubs — never raw URIs
+      // (a signed URL is a bearer credential that looks like a location).
+      return { type: 'text', text: referenceStubOrNull(block, provenance) ?? '[reference]' };
+
+    default: {
+      // Unknown wire block types previously fell off the exhaustive switch
+      // and propagated `undefined` into ContentBlock[]. Fail visibly. A type
+      // that isn't a string is no type, and is never converted to one: an
+      // object can throw when it is.
+      const type: unknown = (block as { type?: unknown }).type;
+      return { type: 'text', text: `[unrecognized content block: ${typeof type === 'string' ? type : 'untyped'}]` };
+    }
+  }
+}
+
+/** A string with something in it: the only data, mimeType or uri a block's
+ *  source is built from, and the only uri that makes it a reference. Anything
+ *  else a sender puts there leaves the block without it, so conversion never
+ *  throws and never copies a non-string. */
+function isFilledString(value: unknown): value is string {
+  return typeof value === 'string' && value !== '';
+}