Add concat_flatten + merge_all reducers; activate 0035/0036 fixtures

[chris-colinsky]

Summary

Bumps the spec submodule v0.26.1 → v0.27.1 and lands the last two proposals of the v0.10.0 batch: 0035 (Langfuse graph-topology fixtures, un-deferred) and 0036 (the concat_flatten + merge_all fan-out collection reducers).

Proposal 0036 — fan-out collection reducers

• concat_flatten — the list-of-lists analog of append. A fan-out subgraph emitting list[X] per instance lands list[list[X]] at the parent target_field; this reducer flattens one level onto prior.
• merge_all — the list-of-mappings analog of merge. A fan-out subgraph emitting dict[str, X] per instance lands list[dict]; this reducer folds the sequence into prior with shallow last-write-wins per key.

Both strict like their single-level counterparts — they raise TypeError on a bad update-element shape, which the engine wraps as ReducerError per graph-engine §4. Exported from openarmature.graph, registered in the conformance adapter.

No fan-out config-validation change needed — OA never restricted target_field to append (it only checks field declaration), so the spec's "relax your validation" caveat doesn't apply.

Proposal 0035 — Langfuse graph-topology fixtures un-deferred

031/032/033 activated in the Langfuse conformance harness. Spec v0.27.1 patched the two fixture-vs-impl ambiguities raised in the clarify-subgraph-name-semantics coord thread (msg 04): fixture 031's outer_out step 2→3 per the §6 shared counter; fixture 033's detached-trace inner namespace → wrapper node name. The Option A subgraph_identity wiring already on main satisfies both — no impl change, just the un-defer + version bump.

Ported the OTel harness's _patch_unsupported_directives into the Langfuse harness so the topology fixtures' update_pure_from_state inner nodes (computed values the structural assertions don't inspect) run as no-ops.

Other

• Conformance adapter parses bare list / dict field types (the 0036 fixtures use unconstrained container types so the reducer, not the typed-state layer, is the shape gatekeeper).
• conformance.toml: spec_pin → v0.27.1, [proposals."0036"] added. All of 0031-0036 stay not-yet until the v0.10.0 release PR flips them together.
• Docs: state-and-reducers + fan-out concept pages document the five built-in reducers and the per-instance collection-shape recipe; the AGENTS.md non-obvious-shape note reframed from a custom-reducer workaround to the real built-ins.
• __spec_version__ / pyproject / smoke test → 0.27.1.

Test plan

• 12 new reducer unit tests (success + strict-raise paths for both reducers)
• Conformance: 026-reducer-concat-flatten, 027-reducer-merge-all, Langfuse 031/032/033 all pass
• Full suite — 937 passed, 130 skipped
• ruff check / ruff format --check clean
• pyright clean
• scripts/check_conformance_manifest.py — 32/32 consistent
• tests/test_smoke.py — spec_version consistency (init / pyproject / submodule changelog) green

[Copilot]

Pull request overview

Adds proposal 0036 fan-out collection reducers and updates conformance/spec metadata to v0.27.1, while activating Langfuse topology fixtures from proposal 0035.

Changes:

• Adds concat_flatten and merge_all reducers, exports them, and covers them with reducer unit tests.
• Updates conformance adapter/version pins and enables Langfuse topology fixtures with fixture patching.
• Updates user-facing docs and bundled agent guide for the new reducer patterns.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/openarmature/graph/reducers.py	Implements the two new built-in reducers.
src/openarmature/graph/__init__.py	Exports the new reducers from the public graph API.
tests/unit/test_state_and_reducers.py	Adds reducer success and strict-error tests.
tests/conformance/adapter.py	Registers new reducers and parses bare list/dict fixture types.
tests/conformance/test_observability_langfuse.py	Activates Langfuse topology fixtures and patches unsupported directives.
src/openarmature/__init__.py	Bumps package spec version metadata.
tests/test_smoke.py	Updates smoke assertion for the new spec version.
pyproject.toml	Updates OpenArmature spec metadata.
conformance.toml	Pins conformance to v0.27.1 and adds proposal 0036.
docs/concepts/state-and-reducers.md	Documents five built-in reducers.
docs/concepts/fan-out.md	Documents reducer selection for fan-out collection shapes.
docs/agent/non-obvious-shapes.md	Updates agent docs to recommend built-in reducers.
src/openarmature/AGENTS.md	Updates bundled agent guide with new spec version and reducer guidance.

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