Clarify testing strategy, improve docs and CLI encoding, and add deprecation markers for test-only APIs

AGENTS.md

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+# Guidance for AI agents, bots, and humans contributing to Chronicle Software's OpenHFT projects.
+
+LLM-based agents can accelerate development only if they respect our house rules. This file tells you:
+
+* how to run and verify the build;
+* what *not* to comment;
+* when to open pull requests.
+
+## Language & character-set policy
+
+| Requirement  | Rationale |
+|--------------|-----------|
+| **British English** spelling (`organisation`, `licence`, *not* `organization`, `license`) except technical US spellings like `synchronized` | Keeps wording consistent with Chronicle's London HQ and existing docs. See the [University of Oxford style guide](https://www.ox.ac.uk/public-affairs/style-guide) for reference. |
+| **ISO-8859-1** (code-points 0-255). Avoid smart quotes, non-breaking spaces and accented characters. | ISO-8859-1 survives every toolchain Chronicle uses. |
+| If a symbol is not available in ISO-8859-1, use a textual form such as `>=`, `:alpha:`, `:yes:`. This is the preferred approach and Unicode must not be inserted. | Extended or '8-bit ASCII' variants are *not* portable and are therefore disallowed. |
+| Tools to check ASCII compliance include `iconv -f ascii -t ascii` and IDE settings that flag non-ASCII characters. | These help catch stray Unicode characters before code review. |
+
+## Javadoc guidelines
+
+**Goal:** Every Javadoc block should add information you cannot glean from the method signature alone. Anything else is
+noise and slows readers down.
+
+| Do | Don't |
+|----|-------|
+| State *behavioural contracts*, edge-cases, thread-safety guarantees, units, performance characteristics and checked exceptions. | Restate the obvious ("Gets the value", "Sets the name"). |
+| Keep the first sentence short; it becomes the summary line in aggregated docs. | Duplicate parameter names/ types unless more explanation is needed. |
+| Prefer `@param` for *constraints* and `@throws` for *conditions*, following Oracle's style guide. | Pad comments to reach a line-length target. |
+| Remove or rewrite autogenerated Javadoc for trivial getters/setters. | Leave stale comments that now contradict the code. |
+
+The principle that Javadoc should only explain what is *not* manifest from the
+signature is well-established in the wider Java community.
+
+Inline comments should also avoid noise. The following example shows the
+difference:
+
+```java
+// BAD: adds no value
+int count; // the count
+
+// GOOD: explains a subtlety
+// count of messages pending flush
+int count;
+```
+
+## Build & test commands
+
+Agents must verify that the project still compiles and all unit tests pass before opening a PR. Running from a clean checkout avoids stale artifacts:
+
+```bash
+# From repo root
+mvn -q verify
+```
+
+## Commit-message & PR etiquette
+
+1. **Subject line <= 72 chars**, imperative mood: Fix roll-cycle offset in `ExcerptAppender`.
+2. Reference the JIRA/GitHub issue if it exists.
+3. In *body*: *root cause -> fix -> measurable impact* (latency, allocation, etc.). Use ASCII bullet points.
+4. **Run `mvn verify`** again after rebasing.
+
+### When to open a PR
+
+* Open a pull request once your branch builds and tests pass with `mvn -q clean verify`.
+* Link the PR to the relevant issue or decision record.
+* Keep PRs focused: avoid bundling unrelated refactoring with new features.
+* Re-run the build after addressing review comments to ensure nothing broke.
+
+## What to ask the reviewers
+
+* *Is this AsciiDoc documentation precise enough for a clean-room re-implementation?*
+* Does the Javadoc explain the code's *why* and *how* that a junior developer would not be expected to work out?
+* Are the documentation, tests and code updated together so the change is clear?
+* Does the commit point back to the relevant requirement or decision tag?
+* Would an example or small diagram help future maintainers?
+
+### Security checklist (review **after every change**)
+
+**Run a security review on *every* PR**: Walk through the diff looking for input validation, authentication, authorisation, encoding/escaping, overflow, resource exhaustion and timing-attack issues.
+
+**Never commit secrets or credentials**: tokens, passwords, private keys, TLS materials, internal hostnames, Use environment variables, HashiCorp Vault, AWS/GCP Secret Manager, etc.
+
+**Document security trade-offs**: Chronicle prioritises low-latency systems; sometimes we relax safety checks for specific reasons. Future maintainers must find these hot-spots quickly, In Javadoc and `.adoc` files call out *why* e.g. "Unchecked cast for performance - assumes trusted input".
+
+## Project requirements
+
+See the [Decision Log](src/main/docs/decision-log.adoc) for the latest project decisions.
+See the [Project Requirements](src/main/docs/project-requirements.adoc) for details on project requirements.
+See the [Antora Docs](docs/antora/README.md) for Antora documentation guidelines.
+
+## Elevating the Workflow with Real-Time Documentation
+
+Building upon our existing Iterative Workflow, the newest recommendation is to emphasise *real-time updates* to documentation.
+Ensure the relevant `.adoc` files are updated when features, requirements, implementation details, or tests change.
+This tight loop informs the AI accurately and creates immediate clarity for all team members.
+
+### Benefits of Real-Time Documentation
+
+* **Confidence in documentation**: Accurate docs prevent miscommunications that derail real-world outcomes.
+* **Reduced drift**: Real-time updates keep requirements, tests and code aligned.
+* **Faster feedback**: AI can quickly highlight inconsistencies when everything is in sync.
+* **Better quality**: Frequent checks align the implementation with the specified behaviour.
+* **Smoother onboarding**: Up-to-date AsciiDoc clarifies the system for new developers.
+* **Incremental changes**: AIDE flags newly updated files so you can keep the documentation synchronised.
+
+### Best Practices
+
+* **Maintain Sync**: Keep documentation (AsciiDoc), tests, and code synchronised in version control. Changes in one area should prompt reviews and potential updates in the others.
+* **Doc-First for New Work**: For *new* features or requirements, aim to update documentation first, then use AI to help produce or refine corresponding code and tests. For refactoring or initial bootstrapping, updates might flow from code/tests back to documentation, which should then be reviewed and finalised.
+* **Small Commits**: Each commit should ideally relate to a single requirement or coherent change, making reviews easier for humans and AI analysis tools.
+- **Team Buy-In**: Encourage everyone to review AI outputs critically and contribute to maintaining the synchronicity of all artefacts.
+
+## AI Agent Guidelines
+
+When using AI agents to assist with development, please adhere to the following guidelines:
+
+* **Respect the Language & Character-set Policy**: Ensure all AI-generated content follows the British English and ISO-8859-1 guidelines outlined above.
+  Focus on Clarity: AI-generated documentation should be clear and concise and add value beyond what is already present in the code or existing documentation.
+* **Avoid Redundancy**: Do not generate content that duplicates existing documentation or code comments unless it provides additional context or clarification.
+* **Review AI Outputs**: Always review AI-generated content for accuracy, relevance, and adherence to the project's documentation standards before committing it to the repository.
+
+## Company-Wide Tagging
+
+This section records **company-wide** decisions that apply to *all* Chronicle projects. All identifiers use the <Scope>-<Tag>-xxx prefix. The `xxx` are unique across in the same Scope even if the tags are different. Component-specific decisions live in their xxx-decision-log.adoc files.
+
+### Tag Taxonomy (Nine-Box Framework)
+
+To improve traceability, we adopt the Nine-Box taxonomy for requirement and decision identifiers. These tags are used in addition to the existing ALL prefix, which remains reserved for global decisions across every project.
+
+.Adopt a Nine-Box Requirement Taxonomy
+
+|Tag | Scope | Typical examples |
+|----|-------|------------------|
+|FN |Functional user-visible behaviour | Message routing, business rules |
+|NF-P |Non-functional - Performance | Latency budgets, throughput targets |
+|NF-S |Non-functional - Security | Authentication method, TLS version |
+|NF-O |Non-functional - Operability | Logging, monitoring, health checks |
+|TEST |Test / QA obligations | Chaos scenarios, benchmarking rigs |
+|DOC |Documentation obligations | Sequence diagrams, user guides |
+|OPS |Operational / DevOps concerns | Helm values, deployment checklist |
+|UX |Operator or end-user experience | CLI ergonomics, dashboard layouts |
+|RISK |Compliance / risk controls | GDPR retention, audit trail |
+
+`ALL-*` stays global, case-exact tags. Pick one primary tag if multiple apply.
+
+### Decision Record Template
+
+```asciidoc
+=== [Identifier] Title of Decision
+
+Date:: YYYY-MM-DD
+Context::
+* What is the issue that this decision addresses?
+* What are the driving forces, constraints, and requirements?
+Decision Statement :: What is the change that is being proposed or was decided?
+Alternatives Considered::
+* [Alternative 1 Name/Type]:
+** *Description:* Brief description of the alternative.
+** *Pros:* ...
+** *Cons:* ...
+* [Alternative 2 Name/Type]:
+** *Description:* Brief description of the alternative.
+** *Pros:* ...
+** *Cons:* ...
+Rationale for Decision::
+* Why was the chosen decision selected?
+* How does it address the context and outweigh the cons of alternatives?
+Impact & Consequences::
+* What are the positive and negative consequences of this decision?
+* How does this decision affect the system, developers, users, or operations?
+- What are the trade-offs made?
+Notes/Links::
+** (Optional: Links to relevant issues, discussions, documentation, proof-of-concepts)
+```
+
+## Asciidoc formatting guidelines
+
+### List Indentation
+
+Do not rely on indentation for list items in AsciiDoc documents. Use the following pattern instead:
+
+```asciidoc
+section :: Top Level Section (Optional)
+* first level
+  ** nested level
+```
+
+### Emphasis and Bold Text
+
+In AsciiDoc, an underscore `_` is _emphasis_; `*text*` is *bold*.
+
+### Section Numbering
+
+Use automatic section numbering for all `.adoc` files.
+
+* Add `:sectnums:` to the document header.
+* Do not prefix section titles with manual numbers to avoid duplication.
+
+```asciidoc
+= Document Title
+Chronicle Software
+:toc:
+:sectnums:
+:lang: en-GB
+:source-highlighter: rouge
+
+The document overview goes here.
+
+== Section 1 Title
+```