[ottobolyos]

Summary

Closes the ~200-line hand-written JsonConditionsConverter and rewrites JsonConditions as List<JsonConditionWrapper>-derived so the type shape IS the cppagent JSON v2 wire shape. System.Text.Json's default serializer handles both directions with no custom converter — round-trip is symmetric by construction, no reader-state edge cases to defend against, and the wire is byte-compatible with the pre-refactor output when the emission pipeline uses the same sparse-serialization options.

Filed against dime-connector bug report #15 (jsonconditions-replace-converter-overlay-with-structural-rewrite-at-7-0.md); this is the mtc.net upstream side of that follow-up to #12 (v1 → v2 wire-shape fix). Targeted at the 7.0 major-bump window so the API-break window is already open.

Change

• New JsonConditionWrapper (libraries/MTConnect.NET-JSON-cppagent/Streams/JsonConditionWrapper.cs) — four nullable level properties (Fault/Warning/Normal/Unavailable) with [JsonIgnore(WhenWritingNull)] for the single-key envelope; Value / Level convenience read-side accessors; ToObservation() materialiser; and Of{Fault,Warning,Normal,Unavailable} static factories.
• JsonConditions rewritten to inherit List<JsonConditionWrapper> with three ctors: empty, copy-from-wrappers, and the legacy IEnumerable<IObservationOutput> overload — the last preserves the historical FAULT → WARNING → NORMAL → UNAVAILABLE level-order emission so JsonComponentStream's call site is a drop-in replacement.
• JsonConditionsConverter deleted — the entire class.

Behavioral changes (intentional at 7.0)

• Legacy MTConnect JSON v1 object-keyed READ compat is dropped. The default List<T> deserializer only reads arrays; the pre-7.0 fallback to {"Fault":[…], "Warning":[…]} envelope is removed. #12 already flipped the write path to v2; this closes the same transition on the read path.
• Mixed-level wire interleaving is no longer re-bucketed by level on write. Insertion order is preserved end-to-end. Producers that want the historical level-order can either use the IEnumerable<IObservationOutput> ctor (unchanged) or sort explicitly before construction.
• Strict malformed-wrapper rejection with named JsonException messages is dropped. Default S.T.J tolerance applies; malformed input produces default S.T.J errors instead of custom prose.

Dime review cycle 1

Retroactive backfill (2026-08-20). The 6-agent Ultrareview cycle ran on this PR and its findings landed atomically in commit aa9c84c0 (fix(json-cppagent): close Ultrareview findings on JsonConditions surface) with supporting failure-path pins in 00c6ab23 (test(json-cppagent): pin dropped-converter failure paths + level accessor precedence). Ledger reconstruction from commit history:

• [TEST] test-coverage-audit — dropped-converter failure paths (malformed wrapper, mixed-level ordering) + Level accessor precedence on multi-property wrappers required behavior pins; landed in 00c6ab2.
• [FINDING] code-review — JsonConditionWrapper.Level/Value read-side accessor precedence needed explicit tie-break behaviour when multiple level properties are populated; closed in aa9c84c.
• [DOCS] documentation-audit — XML /// docs on the new public surface (JsonConditionWrapper, its factories, JsonConditions ctors) required tightening for the 7.0 API break; closed in aa9c84c.
• [SIMPLIFY] simplification — verified the structural rewrite is at minimum shape: 4 nullable level properties + [JsonIgnore(WhenWritingNull)] gives the single-key envelope with zero custom converter code.
• [FINDING:A08] security-audit — deserialization surface reviewed; default S.T.J tolerance is intentional at the 7.0 break window per PR body's "Behavioral changes" section.
• [IMPROVE] improvement — no impact-ranked follow-ups surfaced beyond the accessor-precedence + docs items already fixed in aa9c84c.

(Zero unfixed findings — Ready-eligible.)

Depends on

• fix: clean every Release-pack warning and add multi-TFM CI gate #219 — infrastructure dep — warnings-clean base needed for own 0-warnings Completed verification
• chore: apply dotnet format baseline and add CI gate #230 — infrastructure dep — format-baseline needed for own 0-warnings Completed verification