fix(artifacts): describe incomplete Interface Builder graphs accurately

graph.truncated is also set for invalid archives, omitted dictionary keys
and fixed decode budgets, not only caller-selected limits, so the view's
unknown now points at coverage and limitations for the cause. The MCP
test requests the summary first and reads its retained pages before any
complete call, covering the flow where complete delivery cannot fit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/mcp-contracts.md

@@ -252,7 +252,7 @@ Collections are `documents`, `nodes`, `edges`, and `coverage`; for nodes and
 edges an optional `document` keeps rows whose evidence names that exact decoded
 `relative_path`, and an undecoded path is refused. The summary keeps every
 decoded document, the provider, node-kind, edge-relation and coverage-status
-counts, and decoder truncation. Each page repeats `source_truncated`. A complete
+counts, and whether the decoded graph is incomplete. Each page repeats `source_truncated`. A complete
 app graph often exceeds the default MCP response budget (XLD.app: 6.7 MB), so
 select `detail: "summary"` on the first call. Delivery detail never reaches the
 decoder or changes the source Evidence ID.

docs/native-investigation.md

@@ -328,7 +328,7 @@ complete observation.
   "Contents/Resources/Base.lproj/MainMenu.nib", offset: 0, limit: 64}`.
   `document` selects rows whose evidence names that exact
   `documents[].relative_path` (nodes and edges only); `source_truncated` keeps
-  decoder truncation visible on every page. `verify:interface-builder` compiles
+  graph incompleteness visible on every page. `verify:interface-builder` compiles
   a source-owned AppKit XIB with `ibtool`. Storyboards require an installed
   iOS platform; unsupported archive forms remain explicit.
   XML plist archives accept UTF-8 and BOM-marked UTF-16 in either byte order.