fix(process): reject deep trace cycles without recursive expansion

Use iterative cycle detection, memoized reachability and compact unordered-group membership. Preserve declaration diagnostics on cyclic input while skipping checks requiring a valid partial order. Report duplicate group declarations once instead of repeating pair errors.

Replace redundant source cycle/missing-pair assertions with public CLI/MCP coverage including 6000 events, dense not-before constraints and a large unordered group. Validate acyclic branching and mixed relation semantics. Document bounded Flameox CPU/latency gains and higher observed peak memory; agent/model costs remain unmeasured.

experiments/analysis-efficiency/process-trace-validation.md

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+# Process trace validation
+
+A 6,000-event directed cycle previously overflowed the JavaScript stack inside
+the schema refinement. Cycle detection now uses iterative topological traversal.
+Reachability is computed once per queried origin; cyclic inputs retain
+independent declaration diagnostics without expanding all event pairs. Unordered
+declarations retain group membership, with one diagnostic per overlapping group,
+instead of allocating a pair set and repeating the same error for every pair.
+Valid partial orders still receive complete pair validation.
+
+## Bounded comparison
+
+Flameox ran three randomized paired blocks (seed 917), each limited to 20 seconds
+and 512 MiB. Node 24.18.0 used a 384-MiB old-space limit on macOS arm64. Each
+process validated the same 2,500-event acyclic chain four times, then checked the
+known 6,000-event cycle failure with per-event not-before constraints and one
+unordered group containing every event. All six executions passed the embedded answer
+digest and expected rejection checks.
+
+The baseline source is from `bb540826d`; the candidate includes this trace fix.
+Both modules had TypeScript annotations removed with Node's identical built-in
+transform and used the same copied runtime dependencies. This isolates schema
+validation rather than comparing complete packaged CLI/MCP processes.
+
+| Median measurement                           | Baseline | Candidate |
+| -------------------------------------------- | -------: | --------: |
+| First validation elapsed milliseconds        |   335.80 |    177.25 |
+| Warm validation elapsed milliseconds         |   313.36 |    165.23 |
+| First validation CPU milliseconds            |   366.85 |    218.39 |
+| Warm validation CPU milliseconds             |   335.32 |    194.08 |
+| Whole-process elapsed milliseconds           | 1,344.13 |    787.00 |
+| Process CPU milliseconds before final report | 1,457.67 |    941.05 |
+| Peak process-family MiB                      |   328.36 |    395.52 |
+
+The input is identical: 233,095 JSON bytes, estimated at 77,010 tokens by tokenx
+1.3.0. The valid parsed result digest is
+`28bd99ce83f0da8e45600ef20f114cb52bb26b5f5e6bfc1601ca3e712eaf3147`.
+Actual agent tokens, catalog injection, transport, model reasoning and provider
+costs were not measured. This is a component measurement, not an end-to-end
+investigation speed claim.
+
+First validation excludes module import and fixture preparation; warm runs reuse
+the process but create fresh per-validation graph state. Whole-process elapsed
+includes startup, imports, all four validations, the cyclic-input check, token
+estimation and reporting. CPU includes startup through metrics publication;
+peak RSS covers the complete single-process workload, with no children. Host
+caches were not flushed. Peak memory increased in this cohort. The remaining
+valid-order closure and pair validation can still require quadratic resources.
+Three pairs describe this fixture only.
+
+Preserved Flameox evidence:
+`d6211639446e8b6ec2e82636913eaf471def96673e28f03e9c7f98bec07f8e13`;
+analysis `e663b6bd8f5693975542d5b5e2b18437b3c167a0be939bb7386eb68549936231`.
+An earlier cohort lost modules during another checkout build; its three failed
+executions and timing results are excluded. The successful cohort uses an
+isolated runtime copy. Source-module SHA-256 values are
+`a7729faa2183b0e493b9ac4fc55f6feaee5b2e5294be13d1b29b57a44b899788`
+(baseline) and `725409ce84902125941251037a8a214ccc3c1eec577e484c164c361ca580d693`
+(candidate).