refactor(mcp): shared trim util + global response size-budget net

[Vishnuujain]

De-duplicates payload-trimming logic across MCP tools and adds a dispatch-level size cap so every tool is bounded.

What

• New McpResponseTrim — single home for the truncation budgets, the 100k size cap, the truncate helpers, and the embedding/vector field list (previously copy-pasted across 4 tools).
• New McpParams — shared getInt/getBoolean/getDouble arg coercion (replaces 3 private copies).
• Global size net in DefaultToolContext — serializes the result once; if it exceeds 100k chars, returns a compact truncated:true envelope. This is the floor for tools with no per-tool trim (get_entity_details, get_test_definitions).
• Error messages null-guarded — broad catches no longer surface "... null" when an exception has no message.

Notes

• Behavior-preserving: the two truncate conventions are kept distinct; per-tool smart trims (search proportional drop, lineage/RCA actionable hints) are unchanged — the global net only adds a floor.
• Backend repositories and the ES lineage paths are untouched.
• 98 unit tests pass; live-verified against a running MCP server (no payload-shape change, no vector-key leaks).

[github-actions]

❌ PR checklist incomplete

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[github-actions]

🟡 Playwright Results — all passed (14 flaky)

✅ 4264 passed · ❌ 0 failed · 🟡 14 flaky · ⏭️ 88 skipped

Shard	Passed	Failed	Flaky	Skipped
🟡 Shard 1	300	0	1	4
🟡 Shard 2	803	0	1	9
🟡 Shard 3	806	0	5	8
🟡 Shard 4	846	0	1	12
🟡 Shard 5	718	0	3	47
🟡 Shard 6	791	0	3	8

🟡 14 flaky test(s) (passed on retry)

• Features/Pagination.spec.ts › should test Table columns complete flow with search (shard 1, 1 retry)
• Features/DataQuality/BundleSuiteBulkOperations.spec.ts › Create new Bundle Suite with bulk selected test cases (shard 2, 1 retry)
• Features/IncidentManager.spec.ts › Resolving incident & re-run pipeline (shard 3, 1 retry)
• Features/KnowledgeCenterTextEditor.spec.ts › Rich Text Editor - Advanced Blocks (shard 3, 1 retry)
• Features/RTL.spec.ts › Verify Following widget functionality (shard 3, 1 retry)
• Features/UserProfileOnlineStatus.spec.ts › Should not show online status for inactive users (shard 3, 1 retry)
• Flow/ExploreAggregationCountsMatching.spec.ts › should verify left panel counts and tab search results for normal search (shard 3, 1 retry)
• Flow/PersonaFlow.spec.ts › Set default persona for team should work properly (shard 4, 1 retry)
• Pages/Entity.spec.ts › Tier Add, Update and Remove (shard 5, 1 retry)
• Pages/EntityDataSteward.spec.ts › Tier Add, Update and Remove (shard 5, 1 retry)
• Pages/ExplorePageRightPanel_KnowledgeCenter.spec.ts › Should remove user owner for knowledgeCenter (shard 5, 1 retry)
• Pages/Lineage/LineageFilters.spec.ts › Verify lineage schema filter selection (shard 6, 1 retry)
• Pages/Lineage/LineageRightPanel.spec.ts › Verify custom properties tab IS visible for supported type: searchIndex (shard 6, 1 retry)
• Pages/Lineage/PlatformLineage.spec.ts › Verify domain platform view (shard 6, 1 retry)

📦 Download artifacts

How to debug locally

# Download playwright-test-results-<shard> artifact and unzip
npx playwright show-trace path/to/trace.zip    # view trace

[gitar-bot]

Code Review ✅ Approved

Consolidates payload-trimming logic and parameter coercion into centralized utilities, and implements a global response size-budget net across MCP tools. All functions maintain original truncation behavior while preventing overflows for previously unbounded responses.

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