diff --git a/Makefile b/Makefile
index e8578cfe..7e5b4d39 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: help all clean test build release lint fmt check-fmt markdownlint nixie
+.PHONY: help all clean test build release lint fmt check-fmt typecheck markdownlint nixie
 
 
 TARGET ?= podbot
@@ -37,6 +37,9 @@ fmt: ## Format Rust and Markdown sources
 check-fmt: ## Verify formatting
 	$(CARGO) fmt --all -- --check
 
+typecheck: ## Run static type and borrow checks
+	$(CARGO) check $(CARGO_FLAGS)
+
 markdownlint: ## Lint Markdown files
 	$(MDLINT) '**/*.md'
 
diff --git a/docs/execplans/2-2-6-define-reusable-reference-document-model.md b/docs/execplans/2-2-6-define-reusable-reference-document-model.md
new file mode 100644
index 00000000..ce2b1f85
--- /dev/null
+++ b/docs/execplans/2-2-6-define-reusable-reference-document-model.md
@@ -0,0 +1,341 @@
+# Step 2.2.6: define reusable reference-document model
+
+This ExecPlan (execution plan) is a living document. The sections
+`Constraints`, `Tolerances`, `Risks`, `Progress`, `Surprises & discoveries`,
+`Decision log`, and `Outcomes & retrospective` must be kept up to date as work
+proceeds.
+
+Status: DRAFT
+
+## Purpose and big picture
+
+Deliver canonical content primitives that are independent from ingestion-job
+lifecycle so host and guest profile documents can be modelled, versioned, and
+bound consistently across series.
+
+After implementation, teams can create and revise a `ReferenceDocument`, link
+it to a series profile through `ReferenceBinding`, and query contracts through
+repository ports and API endpoints without coupling to ingestion internals.
+
+Success is visible through three artefacts and one behavioural proof set:
+
+- an approved entity-relationship (ER) diagram for `ReferenceDocument`,
+  `ReferenceDocumentRevision`, and `ReferenceBinding`;
+- glossary entries that define all three entities and their invariants;
+- documented repository and API contract acceptance criteria;
+- passing unit tests (`pytest`) and behavioural tests (`pytest-bdd`) proving
+  model invariants and end-user flows.
+
+## Constraints
+
+- Preserve hexagonal dependency direction: domain and application layers must
+  not import Falcon, SQLAlchemy, or transport-specific types.
+- Define ports (repository contracts) in the domain or application boundary;
+  adapters implement ports.
+- Keep the model explicitly independent from ingestion-job scope. No foreign
+  keys, service calls, or naming that require ingestion-job entities.
+- Include series-aligned host and guest profile document support in both schema
+  and contracts.
+- Keep existing externally published API behaviour backward compatible unless a
+  documented, approved contract change is unavoidable.
+- Ensure design decisions are recorded in the design document.
+- Ensure end-user behavioural changes are documented in `docs/users-guide.md`.
+- Ensure internal interface and operational guidance are documented in
+  `docs/developers-guide.md` (create file if missing).
+- Mark roadmap item `2.2.6` as done only after all acceptance checks pass.
+
+## Tolerances (exception triggers)
+
+- Scope: stop and escalate if implementation exceeds 16 files or 700 net lines
+  before tests and docs updates.
+- Interface: stop and escalate if a breaking public API contract change is
+  required without an explicit migration path.
+- Dependencies: stop and escalate before adding new runtime dependencies.
+- Ambiguity: stop and escalate if `docs/roadmap.md` and repository roadmap
+  location disagree and this affects completion tracking.
+- Validation: stop and escalate if `make check-fmt`, `make typecheck`,
+  `make lint`, or `make test` fails after two focused fix passes.
+
+## Risks
+
+- Risk: Referenced context docs may be missing or outdated.
+  Severity: high. Likelihood: medium. Mitigation: verify each referenced file
+  at Stage A; if absent, create a documented substitute and record the
+  superseding decision in the design doc.
+
+- Risk: Existing persistence schema may embed ingestion assumptions indirectly.
+  Severity: high. Likelihood: medium. Mitigation: model review against current
+  schema and service calls, with a migration note for any decoupling edits.
+
+- Risk: Contract drift between repository ports and API payloads.
+  Severity: medium. Likelihood: medium. Mitigation: define acceptance criteria
+  as executable tests and keep a single glossary-backed vocabulary for field
+  names.
+
+- Risk: Requested Python validation commands may not map directly to the
+  current repository toolchain.
+  Severity: medium. Likelihood: high. Mitigation: in Stage A, document the
+  authoritative command mapping (for example, `pytest`/`pytest-bdd` versus
+  existing workspace gates) before implementation begins.
+
+## Context and orientation
+
+This task implements roadmap item `2.2.6` under canonical content foundation.
+The implementation centres on three core entities:
+
+- `ReferenceDocument`: canonical document identity and stable metadata.
+- `ReferenceDocumentRevision`: immutable revision snapshots of document
+  content.
+- `ReferenceBinding`: relationship between a series profile context
+  (host/guest) and a selected document revision.
+
+Series alignment requirement:
+
+- host profile and guest profile documents are first-class bindings in the same
+  model, not separate ad-hoc tables.
+
+Referenced documents from the task request:
+
+- `docs/roadmap.md`
+- `docs/episodic-podcast-generation-system-design.md`
+- `docs/async-sqlalchemy-with-pg-and-falcon.md`
+- `docs/testing-async-falcon-endpoints.md`
+- `docs/testing-sqlalchemy-with-pytest-and-py-pglite.md`
+- `docs/agentic-systems-with-langgraph-and-celery.md`
+
+If any referenced document is missing, this plan treats that as an explicit
+Stage A deliverable: create or supersede with documented rationale before
+implementation proceeds.
+
+## Interfaces and dependencies
+
+Repository port contracts are defined at the boundary using Protocol interfaces
+(or equivalent abstract contracts) and consumed by application services.
+Adapters provide SQLAlchemy-backed implementations.
+
+```python
+from typing import Protocol, Sequence
+
+class ReferenceDocumentRepository(Protocol):
+    async def create_document(self, command: CreateReferenceDocument) -> ReferenceDocument: ...
+    async def get_document(self, document_id: ReferenceDocumentId) -> ReferenceDocument | None: ...
+    async def add_revision(self, command: AddReferenceDocumentRevision) -> ReferenceDocumentRevision: ...
+    async def list_revisions(
+        self,
+        document_id: ReferenceDocumentId,
+    ) -> Sequence[ReferenceDocumentRevision]: ...
+
+class ReferenceBindingRepository(Protocol):
+    async def bind_revision(self, command: BindReferenceRevision) -> ReferenceBinding: ...
+    async def get_binding(
+        self,
+        series_id: SeriesId,
+        profile_kind: ProfileKind,
+    ) -> ReferenceBinding | None: ...
+```
+
+API contract surface (Falcon) remains transport-only:
+
+- `POST /reference-documents`
+- `POST /reference-documents/{document_id}/revisions`
+- `PUT /series/{series_id}/profiles/{profile_kind}/reference-binding`
+- `GET /series/{series_id}/profiles/{profile_kind}/reference-binding`
+
+`profile_kind` accepts `host` and `guest`.
+
+## Plan of work
+
+### Stage A: baseline, source verification, and architecture boundary lock
+
+Verify referenced docs, roadmap path, and existing architecture seams. Document
+any missing docs or path mismatches before implementation.
+
+Deliverables:
+
+- validated source list (or superseding docs list);
+- explicit architecture boundary note for ports and adapters;
+- approved file-level implementation map.
+
+Go/no-go: proceed only when the source of truth for roadmap and design docs is
+unambiguous.
+
+### Stage B: domain model and ER design
+
+Define domain entities and invariants independent of ingestion-job scope.
+Produce the ER diagram and glossary entries.
+
+Deliverables:
+
+- entity definitions for `ReferenceDocument`,
+  `ReferenceDocumentRevision`, and `ReferenceBinding`;
+- Mermaid ER diagram in the design doc;
+- glossary entries for all three entities and key fields;
+- documented host/guest profile binding rules.
+
+Go/no-go: proceed only when ER and glossary are approved by maintainers.
+
+### Stage C: repository ports and persistence adapter
+
+Define repository contracts in the boundary layer and implement SQLAlchemy
+adapters. Ensure adapters conform to ports and remain infrastructure-isolated.
+
+Deliverables:
+
+- repository Protocol interfaces and DTOs/commands;
+- SQLAlchemy models and mapping logic for three entities;
+- migration scripts for new tables/indexes/constraints;
+- acceptance criteria for repository contract behaviour.
+
+Go/no-go: proceed only when port-level unit tests pass.
+
+### Stage D: API contract and behavioural flows
+
+Expose the model via Falcon endpoints for create, revise, bind, and read flows
+with series host/guest profile support.
+
+Deliverables:
+
+- request and response schemas for the endpoints;
+- API acceptance criteria documented in developers guide;
+- behavioural scenarios for success, conflict, and not-found paths.
+
+Go/no-go: proceed only when endpoint behavioural tests pass.
+
+### Stage E: documentation, roadmap closure, and quality gates
+
+Record decisions and operational guidance, then run required checks.
+
+Deliverables:
+
+- design decision updates in the design document;
+- end-user behaviour updates in `docs/users-guide.md`;
+- internal contract guidance in `docs/developers-guide.md`;
+- roadmap item `2.2.6` marked done;
+- passing `make check-fmt`, `make typecheck`, `make lint`, and `make test`.
+
+## Concrete steps
+
+Run from repository root with `set -o pipefail` and `tee` log capture.
+
+```bash
+set -o pipefail
+LOG_BASE="/tmp/2-2-6-reference-document-model"
+
+make check-fmt 2>&1 | tee "${LOG_BASE}-check-fmt.log"
+make typecheck 2>&1 | tee "${LOG_BASE}-typecheck.log"
+make lint 2>&1 | tee "${LOG_BASE}-lint.log"
+make test 2>&1 | tee "${LOG_BASE}-test.log"
+
+pytest tests/unit -k "reference_document or reference_binding" 2>&1 | tee "${LOG_BASE}-pytest-unit.log"
+pytest tests/bdd -k "reference_document or reference_binding" 2>&1 | tee "${LOG_BASE}-pytest-bdd.log"
+```
+
+Expected success indicators:
+
+```plaintext
+make check-fmt   # exits 0
+make typecheck   # exits 0
+make lint        # exits 0
+make test        # exits 0
+pytest ...       # reports all selected tests passed
+```
+
+If a command fails, fix, rerun the failing command, then rerun full gates.
+
+## Validation and acceptance
+
+Finish line is reached only when all criteria below are true:
+
+- ER diagram for the three entities is merged and explicitly approved.
+- Glossary includes complete definitions for `ReferenceDocument`,
+  `ReferenceDocumentRevision`, and `ReferenceBinding`.
+- Repository contracts are documented and enforced by unit tests.
+- API contracts are documented and enforced by behavioural tests.
+- Host and guest series profile bindings are demonstrably supported.
+- `make check-fmt`, `make typecheck`, `make lint`, and `make test` pass.
+- Unit tests pass under `pytest`.
+- Behavioural tests pass under `pytest-bdd`.
+- Design decisions are recorded in the design document.
+- End-user behaviour is documented in `docs/users-guide.md`.
+- Internal guidance is documented in `docs/developers-guide.md`.
+- Roadmap item `2.2.6` is marked done.
+
+## Idempotence and recovery
+
+All plan stages are additive and can be rerun safely.
+
+If a stage partially applies:
+
+- revert only incomplete hunks for that stage;
+- rerun stage-local tests first;
+- rerun full quality gates before progressing.
+
+Keep command logs in `/tmp` with stage-specific names to preserve evidence
+across retries.
+
+## Artifacts and notes
+
+Implementation evidence should include:
+
+- ER diagram snippet and review approval reference;
+- final glossary section excerpt;
+- repository contract doc excerpt;
+- API acceptance criteria excerpt;
+- gate command summaries with exit codes.
+
+## Progress
+
+- [x] (2026-02-28 UTC) Collected skill guidance (`execplans`,
+      `hexagonal-architecture`) and repository constraints.
+- [x] (2026-02-28 UTC) Drafted ExecPlan for roadmap task `2.2.6` at
+      `docs/execplans/2-2-6-define-reusable-reference-document-model.md`.
+- [x] (2026-02-28 UTC) Added `make typecheck` gate support in `Makefile` and
+      validated `make check-fmt`, `make typecheck`, `make lint`, and
+      `make test` all pass.
+- [ ] Verify roadmap source file location and ensure `2.2.6` exists.
+- [ ] Implement domain model, ports, adapters, and API contracts.
+- [ ] Add and pass unit (`pytest`) and behavioural (`pytest-bdd`) tests.
+- [ ] Update design, user, and developer documentation.
+- [ ] Run all quality gates and mark roadmap item done.
+
+## Surprises & discoveries
+
+- Observation: `docs/roadmap.md` is absent; the repository currently contains
+  `docs/podbot-roadmap.md`.
+  Evidence: `rg --files | rg 'roadmap\\.md$'` returned
+  `docs/podbot-roadmap.md` only. Impact: Stage A must confirm whether to add
+  `docs/roadmap.md` or map task `2.2.6` into the existing roadmap document.
+
+- Observation: Referenced design and testing docs may be absent.
+  Evidence: path validation is required before implementation. Impact:
+  superseding docs may need to be created before contract design.
+
+## Decision log
+
+- Decision: Use hexagonal architecture as a hard boundary for this feature.
+  Rationale: preserves domain independence and adapter testability while
+  matching requested architectural scope. Date/Author: 2026-02-28 / Codex
+
+- Decision: Treat missing referenced docs as explicit Stage A deliverables
+  rather than silent substitutions. Rationale: prevents hidden assumptions and
+  keeps approval criteria auditable. Date/Author: 2026-02-28 / Codex
+
+- Decision: Define acceptance criteria as executable tests plus documentation
+  artefacts. Rationale: the task finish line requires both behavioural proof
+  and explicit contract documentation. Date/Author: 2026-02-28 / Codex
+
+- Decision: Add a `typecheck` Makefile target to satisfy required gate
+  execution in this repository.
+  Rationale: the requested quality gates explicitly require `make typecheck`,
+  and the target did not exist before planning work.
+  Date/Author: 2026-02-28 / Codex
+
+## Outcomes & retrospective
+
+Pending implementation. This section will be completed when the feature reaches
+Status: COMPLETE.
+
+## Revision note
+
+Initial draft created on 2026-02-28 to scope roadmap item `2.2.6` with
+hexagonal boundaries, test strategy, and documentation obligations.