feat(v1.5.0): temp-table data flow and internal resilience (D, F, E)

[ikelaiah]

PR: v1.5.0 — Data flow and internal resilience

Summary

Implements the v1.5.0 — Data flow and internal resilience milestone from
ROADMAP.md: Workstream D in full, F data-flow rendering in both exporters,
and the E construct-coverage statistic surfaced in the UI. The golden suite
grows from 188 to 199; fuzz (400) and UI (13 → 14) suites stay green.

What's included

Temporary-table producer→consumer data edges (D)

buildGraph (src/ir.ts) now tracks temp-table (#name) writes as reaching
definitions while emitting the flow graph. A consumer wires to its unique
reaching definition — the most recent write on a provably linear path — with a
labelled semantic data edge:

• SELECT … INTO #stage → later UPDATE #stage / SELECT … FROM #stage /
  INSERT … SELECT … FROM #stage consumers form a visible pipeline.
• A write to an existing temp table (a read-modify write such as UPDATE #t)
  also consumes the current content, so chains stay connected.
• Conditional writes and branch/loop/try merges mark the definition ambiguous:
  no data edge is invented for its consumers, and a region-scoped
  informational temp_flow_ambiguous annotation explains why. Info
  annotations never inflate the findings count.
• Unreachable statements neither wire nor redefine temp tables.
• Resolved data edges are counted in graph.stats.dataflow and in construct
  coverage as temp_flow.

Conservative external nodes (D)

In the estate dependency graph (dependencyGraph), an unmatched three- or
four-part name now renders with its complete identity —
external: remotesrv.salesdb.dbo.pull_orders — instead of a bare name that
could be mistaken for a known object. Unmatched non-temp targets carry
provenance: 'external' (previously misclassified synthetic); temp tables
are workspace-internal and remain synthetic.

Transaction edge cases (D)

• Savepoint-only recovery: savepoints declared in a TRY body remain
  visible inside its CATCH, so ROLLBACK TRANSACTION stage_save is
  annotated "roll back to savepoint stage_save; depth unchanged" instead of
  "named target unresolved; full or savepoint rollback".
• SET XACT_ABORT inside CATCH is annotated "set inside CATCH; applies
  to later statements", distinguishing handler-scoped changes from
  procedure-level settings.

Data-flow rendering in both exporters (F)

Data edges derive their presentation from the semantic data edge kind via
the canonical mapping:

• Mermaid emits a linkStyle entry (green, 2 px) covering every data edge.
• draw.io edges with kind="data" render with strokeWidth=2 on top of the
  existing canonical stroke colour and data-procflow-kind metadata.

Reviewed accuracy correction

v1.1.0 classified every sequential edge leaving an io/src node as a
semantic data edge, conflating control flow with data flow. With real
producer→consumer data edges shipping in v1.5.0, that mapping is removed:
sequential edges are control, and only explicit temp-table edges and
dependency-graph writes are data. The v1.1.0 semantic fixture in
tests/tests.ts now stages through #work so it still asserts a genuine
data edge. No other golden output changed.

Construct coverage in the UI (E)

The analysis panel gains a Constructs signal next to Confidence, Coverage,
and Diagnostics: resolved/detected in the header strip, and a Details line
with the full detected/resolved/opaque counts plus the per-kind breakdown
(branches, loops, handlers, CTEs, source refs, temp flow). Estate scope
aggregates the statistic across all objects.

Not changed

• Existing v1.1.0–v1.4.0 boundary, procedural, transaction, and query
  semantics are untouched; all prior fixtures remain green except the one
  documented correction above.
• Confidence formula, layout engine, catalogue resolution, and column
  lineage are deferred per the roadmap.
• The local-only security model is unchanged.

Fixtures

• tests/dialects/tsql.ts — four v1.5.0 graph fixtures: linear temp-table
  pipeline (kind-asserted data edges), conservative branch merge
  (temp_flow_ambiguous, no invented edges), savepoint-only recovery in
  CATCH, and catch-scoped SET XACT_ABORT.
• tests/tests.ts — matchingWire can now assert edge kind; v1.5.0 blocks
  cover external-node labels/provenance, F data-edge rendering in both
  exporters, and construct-coverage counts.
• tests/ui-tests.ts — construct-coverage display assertion.

Verification

• npm run typecheck — passes
• npm run build — passes
• npm run test:file — passes
• Golden suite — 199/199 (was 188)
• Fuzz suite — 400 deterministic mutation cases
• UI suite — 14/14 (was 13)
• Local-only URL check clean; dist/ committed in sync

Deferred (per roadmap)

• Confidence re-score → v1.6.0; layout replacement → v1.7.0
• Catalogue, columns, and RDL → v1.9.0+