feat(membership): refuse episode membership outside the episode

ARCHITECTURE.md

@@ -62,6 +62,7 @@ boundaries above remain the target modular MSA architecture.
 | `tepp_simulation` | known-truth temporal/event data generation |
 | `validation_core` | RMSE, bias, coverage, graph, and Monte Carlo metrics |
 | `tepp_api` | versioned DTO, schema, and export contracts |
+| `episode_membership` | event-time episode membership containment gate |
 | `location_membership` | location is not entity identity and not a language channel |
 | `prompt_source` | prompt boilerplate is not unique latent content and not stopword deletion |
 | `corpus_background` | corpus-background wording is not unique latent content and not stopword deletion |

CHANGELOG.md

@@ -6,6 +6,9 @@ All notable changes to TEPP are documented here. The format follows Keep a Chang
 
 ### Added
 
+- `episode_membership` identity gate: a document's episode membership cannot
+  start before or end after the episode event-time interval; recovered
+  containment flags are compared with known truth (ADR 0003).
 - `semantic_core` binds exact `evidence_core` source spans as semantic units. Language profiles are `unresolved` or a primary ISO 639 subtag with an IANA-registered ISO 3166-1 alpha-2 or UN M.49 region (RFC 5646; IANA File-Date 2026-08-08); private-use and unknown regions fail closed. Unresolved metadata keeps the caller-supplied Korean `측정` span and does not retokenize. `SemanticIdentity::from_language_tag` fails closed. Korean and English report sentences remain distinct units. Not concept alignment, not invariance, not a topic estimator (ADR 0020; issue #168). The APA register cites RFC 5646 once, in the Unicode/language-tags section; the slice-specific note remains `docs/research/span-grounded-semantic-units.md`.
 - `corpus_background` identity gate: corpus-level background wording is not unique latent content or a state transition; recovery tests distinguish background evidence from unique content.
 - `modality_source` identity gate: non-lexical modality is not unique lexical content or a state transition; recovery tests keep modality evidence distinct from unique content.

Cargo.toml

@@ -49,6 +49,7 @@ members = [
     "crates/interpretation_gateway",
     "crates/model_selection",
     "crates/checkpoint_authority",
+    "crates/episode_membership",
 ]
 default-members = [
     "crates/evidence_core",
@@ -99,6 +100,7 @@ default-members = [
     "crates/interpretation_gateway",
     "crates/model_selection",
     "crates/checkpoint_authority",
+    "crates/episode_membership",
 ]
 
 [workspace.package]

README.md

@@ -12,23 +12,23 @@ evidence, six-clock temporal values, event mentions/instances, relations,
 membership, persistence, splits, simulation, validation, API DTOs, and the
 predicted-versus-observed promotion gate.
 This branch establishes the Rust workspace, quality-gate foundation, and the
-longitudinal within/between decomposition capability. The eleven bounded crates
+longitudinal within/between decomposition capability. The workspace bounded crates
 compile independently. `longitudinal_core` exposes within/between decomposition
 and component RMSE APIs; the remaining crates expose no placeholder production
 APIs, and domain behavior for them begins in Task 2 with immutable evidence
 identifiers and source records.
 This branch establishes the Task 1 Rust workspace and quality-gate foundation.
-The twelve bounded crates compile independently but intentionally expose no
-The eleven bounded crates compile independently; Task 1 includes the
+The workspace bounded crates compile independently but intentionally expose no
+The workspace bounded crates compile independently; Task 1 includes the
 implemented `encrypted_mapping` crate with AES-256-GCM sealing and
 purpose-bound opening, while the remaining domain behavior begins in Task 2
 with immutable evidence identifiers and source records.
-The eleven bounded crates compile independently. `derived_sensitivity` inherits
+The workspace bounded crates compile independently. `derived_sensitivity` inherits
 source Restricted/Internal classes onto topic, factor, and relation artifacts
 and fails closed on unknown kinds; derivation and blanket PII masking are not
 declassification. Other crates still begin domain behavior in Task 2 with
 immutable evidence identifiers and source records.
-The eleven bounded crates compile independently but intentionally expose no
+The workspace bounded crates compile independently but intentionally expose no
 placeholder production APIs. Domain behavior begins in Task 2 with immutable
 evidence identifiers and source records.
 
@@ -44,6 +44,7 @@ crates/corpus_split
 crates/tepp_simulation
 crates/validation_core
 crates/tepp_api
+crates/episode_membership
 crates/prompt_source
 crates/corpus_background
 crates/modality_source

crates/episode_membership/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "episode_membership"
+description = "Episode membership cannot escape the episode event-time interval."
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+authors.workspace = true
+repository.workspace = true
+homepage.workspace = true
+readme.workspace = true
+keywords.workspace = true
+categories.workspace = true
+publish = false
+
+[lints]
+workspace = true