docs(evidence): finalize restructuring design

docs/agents/domain.md

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+# Domain documentation
+
+This repository uses a single-context domain-documentation layout.
+
+## Sources
+
+Before changing behavior or terminology, read:
+
+1. `CONTEXT.md` at the repository root;
+2. any relevant architectural decision records under `docs/adr/`;
+3. the implementation and tests for the affected module.
+
+`CONTEXT.md` contains the shared domain vocabulary and the system's main
+concepts. Use its terminology consistently in code, documentation, issues, and
+user-facing explanations.
+
+ADRs explain important architectural decisions and their rationale. They are
+created only when a durable decision needs to be recorded; the absence of
+`docs/adr/` is not an error.
+
+If one of these optional sources does not exist, continue without reporting an
+error.
+
+## Layout
+
+```text
+/
+├── CONTEXT.md
+└── docs/
+    └── adr/
+        └── <decision>.md
+```
+
+Do not introduce `CONTEXT-MAP.md` unless the repository later becomes a
+genuine multi-context system whose domains require separate context documents.
+
+## Working with domain concepts
+
+When implementing or reviewing work:
+
+- identify the domain concepts involved;
+- reuse the names defined in `CONTEXT.md`;
+- distinguish domain rules from infrastructure details;
+- avoid creating synonyms for established terms;
+- update `CONTEXT.md` when a new durable concept is introduced or an existing
+  definition materially changes.
+
+For ThothII, the Evidence module and its concepts belong to this shared domain
+context even though Evidence is implemented as an autonomous workflow module.
+
+## Architectural decisions
+
+Create an ADR when a decision:
+
+- affects multiple parts of the system;
+- establishes a durable constraint;
+- selects between meaningful alternatives;
+- would otherwise be difficult to reconstruct later.
+
+Do not create an ADR for routine implementation details.
+
+If current code or a proposed change conflicts with an ADR, flag the conflict
+explicitly. Do not silently override the recorded decision.
+
+## Keeping documentation aligned
+
+When a change affects the domain model:
+
+1. update the implementation;
+2. update the relevant tests;
+3. update `CONTEXT.md`;
+4. add or update an ADR when the decision is architectural;
+5. update linked plans and GitHub issues.
+
+The persisted repository documentation, not the chat transcript, is the
+long-term source of truth.