diff --git a/conformance.toml b/conformance.toml
index d84fbf8..b71f1b1 100644
--- a/conformance.toml
+++ b/conformance.toml
@@ -32,7 +32,7 @@
 
 [manifest]
 implementation = "openarmature-python"
-spec_pin = "v0.84.0"
+spec_pin = "v0.88.0"
 
 # Status values:
 #   implemented   — shipped behavior matches the proposal's contract
@@ -855,7 +855,41 @@ status = "not-yet"
 
 # Spec v0.84.0 (proposal 0089).  Embedding / rerank typed-event output
 # (graph-engine §6 EmbeddingEvent.output_vectors / RerankEvent.
-# output_results + observability output mappings).  Not-yet;
-# observability fixtures 137/138 defer with it (and re-source 083/108).
+# output_results + observability output mappings).
 [proposals."0089"]
+status = "partial"
+since = "0.16.0"
+note = "The embedding half shipped in 0059b (#198): EmbeddingEvent.output_vectors is populated by OpenAIEmbeddingProvider and rendered as the Langfuse Embedding observation output (observability §8.4.5), sourced event-side per 0089; observability fixtures 083 (re-sourced) + 137 pass. partial because the rerank half is unshipped -- RerankEvent.output_results and the rerank observation output rendering ride the rerank capability (proposal 0060, not-yet); observability fixtures 108 + 138 defer with it."
+
+# Spec v0.85.0 (proposal 0090).  Cohere rerank wire mapping
+# (retrieval-provider §8.4, POST /v2/rerank; backs 0060's Cohere-shaped
+# reference reranker).  Not-yet; the rerank capability (0060) is
+# unshipped, so its wire fixtures 028-031 defer with it.
+[proposals."0090"]
+status = "not-yet"
+
+# Spec v0.86.0 (proposal 0091).  Cohere embeddings wire mapping
+# (retrieval-provider §8.4, POST /v2/embed) extending §8.4 to both
+# Cohere endpoints.  Not-yet; wire fixtures 032-037 defer with it (no
+# harness wire-capture primitive; the Cohere provider is unshipped).
+[proposals."0091"]
+status = "not-yet"
+
+# Spec v0.87.0 (proposal 0092).  Embedding-mapping batch chunking, the
+# general §8 rule (consecutive <=cap chunks, one request each, vectors
+# concatenated in input order, usage summed).  Not-yet; the TEI /embed
+# over-cap fixture 038 defers with it (no embedding wire mapping is
+# shipped).
+[proposals."0092"]
+status = "not-yet"
+
+# Spec v0.88.0 (proposal 0093).  Nullable provider usage records:
+# EmbeddingResponse.usage / RerankResponse.usage become record|null and
+# the embedding usage emission (OTel §5.5.8 gen_ai.usage.input_tokens,
+# Langfuse §8.4.5 usageDetails.input) becomes conditional.  Not-yet; the
+# no-usage fixtures 139-143 defer with it.  Follow-up when they un-defer:
+# widen the shipped EmbeddingResponse.usage to nullable + make its
+# emission conditional; 0060 builds RerankResponse.usage nullable from
+# the start.
+[proposals."0093"]
 status = "not-yet"
diff --git a/openarmature-spec b/openarmature-spec
index 7a974e0..398cdaf 160000
--- a/openarmature-spec
+++ b/openarmature-spec
@@ -1 +1 @@
-Subproject commit 7a974e0b11d0a485b76a34041366612ea1e65b77
+Subproject commit 398cdaf16c88decd7df14f2216f273ec3e3069b0
diff --git a/pyproject.toml b/pyproject.toml
index e4fe4b0..5753893 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -63,7 +63,7 @@ Specification = "https://github.com/LunarCommand/openarmature-spec"
 openarmature = "openarmature.cli:main"
 
 [tool.openarmature]
-spec_version = "0.84.0"
+spec_version = "0.88.0"
 
 [dependency-groups]
 dev = [
diff --git a/scripts/build_agents_md.py b/scripts/build_agents_md.py
index dd9a8e7..54f1ae0 100644
--- a/scripts/build_agents_md.py
+++ b/scripts/build_agents_md.py
@@ -73,7 +73,7 @@
 # Spec capability directory names under ``openarmature-spec/spec/``,
 # in the order they appear in the bundle's "Capability contracts"
 # section. The order matches the order capabilities were introduced
-# (graph-engine first, prompt-management most recent) so an agent
+# (graph-engine first, retrieval-provider most recent) so an agent
 # reading top-down sees the foundational layer before the layers
 # built on top.
 CAPABILITIES = (
@@ -82,6 +82,7 @@
     "llm-provider",
     "observability",
     "prompt-management",
+    "retrieval-provider",
 )
 
 
diff --git a/src/openarmature/AGENTS.md b/src/openarmature/AGENTS.md
index 5be11e3..fede9a9 100644
--- a/src/openarmature/AGENTS.md
+++ b/src/openarmature/AGENTS.md
@@ -1,6 +1,6 @@
 # OpenArmature — Agent documentation
 
-*This is the agent guide bundled with the openarmature Python package, version 0.15.0 (spec v0.84.0). For the full docs site see [openarmature.ai](https://openarmature.ai). For the canonical spec text see [openarmature.org/capabilities](https://openarmature.org/capabilities/). For project-specific conventions for the code you're editing, see the host project's `AGENTS.md` or `CLAUDE.md`.*
+*This is the agent guide bundled with the openarmature Python package, version 0.15.0 (spec v0.88.0). For the full docs site see [openarmature.ai](https://openarmature.ai). For the canonical spec text see [openarmature.org/capabilities](https://openarmature.org/capabilities/). For project-specific conventions for the code you're editing, see the host project's `AGENTS.md` or `CLAUDE.md`.*
 
 ## TL;DR
 
@@ -10,7 +10,7 @@ OpenArmature is a workflow framework for LLM pipelines and tool-calling agents:
 
 ## Capability contracts
 
-_Sourced from openarmature-spec v0.84.0. Each entry below reproduces §1 (Purpose) and §2 (Concepts) of the capability's `spec.md` verbatim — including additions from accepted proposals that this Python implementation may not yet ship. For per-proposal implementation status (implemented / partial / textual-only / not-yet), see the `conformance.toml` manifest at the repo root. For the full spec text (execution model, error semantics, determinism, observer hooks, etc.) see the linked docs site._
+_Sourced from openarmature-spec v0.88.0. Each entry below reproduces §1 (Purpose) and §2 (Concepts) of the capability's `spec.md` verbatim — including additions from accepted proposals that this Python implementation may not yet ship. For per-proposal implementation status (implemented / partial / textual-only / not-yet), see the `conformance.toml` manifest at the repo root. For the full spec text (execution model, error semantics, determinism, observer hooks, etc.) see the linked docs site._
 
 ### Capability: `graph-engine`
 
@@ -460,6 +460,97 @@ variables. Splitting the two operations lets users:
 A convenience operation that combines fetch + render is permitted (see §6) but the spec
 treats fetch and render as separable.
 
+### Capability: `retrieval-provider`
+
+#### 1. Purpose
+
+The retrieval-provider capability is the home for retrieval-primitive provider operations that sit
+alongside LLM completion. The first protocol surface this specification defines is **embedding** —
+turning a list of input strings into a list of vectors via an `EmbeddingProvider`. A sibling
+`RerankProvider` protocol (§5) re-scores a list of candidate documents against a query, returning
+them sorted by relevance — the second retrieval-primitive surface on the same capability.
+
+Retrieval-provider is a sibling capability to `llm-provider` (per proposal 0006),
+not a subtype of it. Embedding and LLM completion both bind per-instance to a model identifier per
+the llm-provider §5 contract, but embedding model identifiers (`text-embedding-3-small`,
+`voyage-3`, `embed-multilingual-v3.0`, etc.) live in disjoint namespaces from completion model
+identifiers (`gpt-4o-mini`, `claude-3-5-sonnet`, etc.). A single Provider abstraction bundling both
+surfaces would either contradict the per-model-binding contract OR carve a different contract shape
+for the same protocol — both bad. Separate protocols preserve per-model-binding while opening a
+path to observable embedding calls.
+
+Retrieval-provider is one of a planned family of `<domain>-provider` capabilities (`llm-provider`,
+`retrieval-provider`, plus future siblings as downstream demand surfaces). Each domain capability
+covers related-shape provider operations under a narrow protocol surface; new domains land as new
+capabilities rather than as extensions to existing ones. This keeps per-capability protocol surface
+narrow and per-domain evolution independent.
+
+The substrate is intentionally narrow, matching llm-provider's posture:
+
+- An `EmbeddingProvider` is **stateless**. It does not cache vectors; the caller passes the full
+  input list on every call.
+- An `EmbeddingProvider` does **not** handle retry, rate limiting, fallback, or routing. Those are
+  pipeline-utilities concerns and compose above the provider via middleware.
+- An `EmbeddingProvider` is **bound to a single model identifier**. Switching models means
+  constructing a new provider, not passing a different argument per call.
+
+**Transparency.** Per charter §3.1 principle 8 ("Transparency over abstraction"), the embedding
+abstraction surfaces a normalized shape — `EmbeddingResponse`, `EmbeddingUsage` — without hiding
+what the underlying provider returned. The `EmbeddingResponse.raw` field carries the parsed provider
+response verbatim alongside the normalized fields, and the error categories preserve the underlying
+provider exception as cause.
+
+#### 2. Concepts
+
+**RetrievalProvider.** The umbrella term covering both `EmbeddingProvider` and `RerankProvider`. Not
+a concrete protocol itself; used as the capability-level descriptor when discussing cross-protocol
+concerns (observability, error semantics, per-model binding).
+
+**EmbeddingProvider.** An object that, given a sequence of input strings, returns a sequence of
+vectors wrapped in an `EmbeddingResponse`. Bound to a specific embedding model identifier per
+instance.
+
+**EmbeddingResponse.** The result of an `embed()` call: the vectors, the model identifier, the
+parsed raw response, and — when present — usage information and the provider-returned request
+identifier.
+
+**EmbeddingUsage.** A usage record carrying `input_tokens` only — embedding has no output tokens
+(vectors aren't tokens).
+
+**Embedding runtime config.** A `RuntimeConfig`-shaped record (parallel to llm-provider §6) carrying
+embedding-specific caller-supplied request parameters: an optional `dimensions` field (for callers
+controlling output vector size on providers that support it), an optional **`input_type`** field, and
+the extras-pass-through bag for vendor-specific knobs. `input_type` (`"query"` / `"document"`, an
+extensible string) declares what the embedded text is *for*, so a provider bound to an asymmetric model
+applies the model-appropriate query/document treatment per its §8 wire mapping; **absent ⇒ symmetric
+embedding** (a symmetric model ignores it). Additional well-known values (`"classification"`,
+`"clustering"`, …) MAY be recognized by mappings whose backend supports them; an unrecognized value is
+`provider_invalid_request` (§7) at a mapping that declares a closed set, or passed through by a mapping
+that accepts arbitrary types. Free-form per-model instruction overrides ride the extras-pass-through
+bag (no second declared field).
+
+**RerankProvider.** An object that, given a query string and a list of candidate documents, returns
+the documents sorted by query-relevance with provider-specific scores. Bound to a specific rerank
+model identifier per instance.
+
+**RerankResponse.** The result of a `rerank()` call: the sorted scored documents, the model
+identifier, the parsed raw response, and — when present — usage information and the
+provider-returned response identifier.
+
+**RerankUsage.** A usage record with optional `search_units` and optional `input_tokens`, reflecting
+the messy provider landscape where rerank pricing surfaces vary widely.
+
+**ScoredDocument.** A single result entry carrying the document's original index in the input list,
+the provider-assigned relevance score, and (optionally) an echo of the document text.
+
+**Rerank runtime config.** A `RuntimeConfig`-shaped record (parallel to llm-provider §6) carrying
+rerank-specific caller-supplied request parameters. Initially minimal: one declared field,
+`return_documents` (boolean, default `False`), controlling whether the provider echoes document text
+on each `ScoredDocument` in the response. The field name + default match the major rerank vendors'
+wire-shape parameter (Voyage AI exposes `return_documents` defaulting `False`; Jina AI's wire default is `True`, so the §8.2 Jina mapping sends the OA value explicitly; Cohere's `/v2/rerank` has no `return_documents` field, so the §8.4 mapping treats the OA knob as a silent no-op);
+per-vendor wire-format mappings pin the source-side translation where a vendor diverges. Plus the
+extras-pass-through bag for vendor-specific knobs.
+
 ## Patterns
 
 _Recipes that compose the primitives. Not framework contracts — these are how to do common things idiomatically._
diff --git a/src/openarmature/__init__.py b/src/openarmature/__init__.py
index 851813c..a0470f8 100644
--- a/src/openarmature/__init__.py
+++ b/src/openarmature/__init__.py
@@ -25,7 +25,7 @@
 """
 
 __version__ = "0.15.0"
-__spec_version__ = "0.84.0"
+__spec_version__ = "0.88.0"
 # Proposal 0052 (spec observability §5.1 / §8.4.1): canonical
 # package-registry name for this implementation. Surfaces on every
 # OTel invocation span as ``openarmature.implementation.name`` and on
diff --git a/tests/conformance/test_fixture_parsing.py b/tests/conformance/test_fixture_parsing.py
index afa1f92..a457696 100644
--- a/tests/conformance/test_fixture_parsing.py
+++ b/tests/conformance/test_fixture_parsing.py
@@ -633,6 +633,17 @@ def _id(case: tuple[str, Path]) -> str:
     "prompt-management/036-prompt-manager-default-cache-ttl": (
         "Proposal 0086 default cache_ttl_seconds; not implemented"
     ),
+    # Proposal 0093 (nullable provider usage records, v0.88.0) -- the rerank
+    # no-usage fixtures use the calls_rerank directive (rerank capability
+    # unshipped, proposal 0060), so they defer at the parse layer like
+    # 099-109 / 138. The embedding no-usage fixtures (139/140/143) parse via
+    # the modelled calls_embed directive.
+    "observability/141-otel-rerank-no-usage-attributes-omitted": (
+        "Proposal 0093 rerank no-usage; rerank capability not implemented (0060)"
+    ),
+    "observability/142-langfuse-rerank-no-usage-usagedetails-omitted": (
+        "Proposal 0093 rerank no-usage; rerank capability not implemented (0060)"
+    ),
 }
 
 
diff --git a/tests/conformance/test_observability.py b/tests/conformance/test_observability.py
index 7f24789..9142432 100644
--- a/tests/conformance/test_observability.py
+++ b/tests/conformance/test_observability.py
@@ -386,6 +386,37 @@ def _reset_otel_global_tracer_provider(restore_to: object) -> None:
     "136-langfuse-parallel-branches-dispatch-span": (
         "Langfuse parallel-branches dispatch-span parity (proposal 0088) not-yet implemented"
     ),
+    # ---- v0.88.0 spec-pin bump (v0.84.0 -> v0.88.0): proposal 0093
+    # nullable provider usage records. The no-usage rendering fixtures defer
+    # with the conditional-emission follow-up (widen the shipped
+    # EmbeddingResponse.usage to nullable + omit the usage attribute /
+    # usageDetails when the provider reports none). ----
+    # 139/140 -- embedding no-usage (OTel span + Langfuse observation).
+    **{
+        fixture_id: "nullable provider usage records (proposal 0093) not-yet implemented"
+        for fixture_id in (
+            "139-otel-embedding-no-usage-input-tokens-omitted",
+            "140-langfuse-embedding-no-usage-usagedetails-omitted",
+        )
+    },
+    # 141/142 -- rerank no-usage; also blocked on the unshipped rerank
+    # capability (proposal 0060).
+    **{
+        fixture_id: (
+            "rerank no-usage rendering (proposal 0093); blocked on the unshipped "
+            "rerank capability (proposal 0060)"
+        )
+        for fixture_id in (
+            "141-otel-rerank-no-usage-attributes-omitted",
+            "142-langfuse-rerank-no-usage-usagedetails-omitted",
+        )
+    },
+    # 143 -- embedding no-usage metric; rides the §11 embedding-metrics path
+    # (proposal 0067), which is itself deferred (cf. 089).
+    "143-embedding-metrics-no-usage-no-token-observation": (
+        "embedding no-usage metric (proposal 0093) rides the deferred §11 "
+        "embedding-metrics path (proposal 0067; cf. 089)"
+    ),
 }
 
 
diff --git a/tests/conformance/test_retrieval_provider.py b/tests/conformance/test_retrieval_provider.py
index 85eb943..2131d64 100644
--- a/tests/conformance/test_retrieval_provider.py
+++ b/tests/conformance/test_retrieval_provider.py
@@ -40,14 +40,20 @@
 # Rerank fixtures (006-012) ride the RerankProvider, which lands with
 # proposal 0060. Deferred so a green run means "what we implement passes."
 #
-# The v0.84.0 pin also pulls in the retrieval-provider WIRE-MAPPING fixtures
-# (013-027) for proposals 0077 (TEI) / 0078 (Jina) / 0079 (OpenAI-compatible),
-# none of which python has shipped. This runner drives only the bundled
+# The v0.84.0 pin bump also introduced the retrieval-provider WIRE-MAPPING
+# fixtures (013-027) for proposals 0077 (TEI) / 0078 (Jina) / 0079
+# (OpenAI-compatible), still present at the current pin, none of which python
+# has shipped. This runner drives only the bundled
 # OpenAIEmbeddingProvider's embed() and asserts the response, so it cannot
 # exercise their request-side mappings (TEI server-side prompt_name, Jina's
 # task, the client-side query/document prefix) -- the contracts those
 # fixtures exist to verify. Defer the whole batch until each wire-mapping
 # impl PR (v0.16.0+).
+#
+# The v0.88.0 pin pulls in the Cohere wire mappings + the general embed
+# batch-chunking rule: 028-031 (0090 Cohere rerank), 032-037 (0091 Cohere
+# embed), 038 (0092 TEI /embed over-cap chunk-and-stitch). None are shipped
+# -- same deferral rationale as 013-027.
 _DEFERRED_FIXTURES: dict[str, str] = {
     **{
         p.stem: "RerankProvider not implemented (proposal 0060 not-yet)"
@@ -74,6 +80,25 @@
         for p in CONFORMANCE_DIR.glob("[0-9][0-9][0-9]-*.yaml")
         if 23 <= int(p.stem[:3]) <= 27
     },
+    **{
+        p.stem: "Cohere rerank wire mapping (proposal 0090) not implemented"
+        for p in CONFORMANCE_DIR.glob("[0-9][0-9][0-9]-*.yaml")
+        if 28 <= int(p.stem[:3]) <= 31
+    },
+    **{
+        p.stem: "Cohere embed wire mapping (proposal 0091) not implemented"
+        for p in CONFORMANCE_DIR.glob("[0-9][0-9][0-9]-*.yaml")
+        if 32 <= int(p.stem[:3]) <= 37
+    },
+    **{
+        p.stem: (
+            "embedding batch-chunking general rule (proposal 0092); the TEI "
+            "/embed over-cap chunk-and-stitch fixture rides the unshipped TEI "
+            "embed wire mapping (proposal 0077)"
+        )
+        for p in CONFORMANCE_DIR.glob("[0-9][0-9][0-9]-*.yaml")
+        if int(p.stem[:3]) == 38
+    },
 }
 
 
diff --git a/tests/test_smoke.py b/tests/test_smoke.py
index e673231..0d7a42e 100644
--- a/tests/test_smoke.py
+++ b/tests/test_smoke.py
@@ -9,7 +9,7 @@
 
 def test_package_versions() -> None:
     assert openarmature.__version__ == "0.15.0"
-    assert openarmature.__spec_version__ == "0.84.0"
+    assert openarmature.__spec_version__ == "0.88.0"
 
 
 def test_spec_version_matches_pyproject() -> None: