CTO-MCP — persona-constitution MCP Server + Agentic PR Review

An MCP (Model Context Protocol) server that serves the Oluwaferanmi Oluwagbamila Agentic Engineering Persona — LLM Operational Constitution v3.0.0 to any MCP-capable coding agent, and a PR review gate that enforces the constitution's Zero-Framework-Tolerance rules on pull requests — as an MCP tool, a CLI, a reusable GitHub Action, and an opencode agent.

Grounded in SWEBOK v4.0 (18 Knowledge Areas), the NASA/JPL Power of 10, and Zero Framework Tolerance.

The constitution exists to counteract a specific, structural LLM failure mode: producing code that has the shape of a solution but none of the substance — skeletons, TODOs, stubs, and "you can extend this to…". This server makes the constitution queryable, ships a scanner that mechanically detects those violations in generated code, and turns that scanner into a diff-aware pull-request reviewer.

The Supreme Law — Every code output must be complete, executable, and correct. Not a scaffold. Not a pattern. Not a direction. Code that runs. Logic that is correct. Implementation that is done.

Requirements

• Python 3.9+ — the test suite is run against CPython 3.9.6 and 3.14.6.
• Zero runtime dependencies. CodebaseCSI (MIT), which backs the scanner, is vendored at codebase_csi/ — provenance, pinned upstream revision, and the local-modification ledger live in codebase_csi/VENDORED.md.
• Optional [ast] extra: tree-sitter grammars that upgrade the scanner from regex to real AST analysis for JavaScript, TypeScript, Java, Go, Rust, Ruby, C and C++. Without it the scanner still runs and says so in its engines output. The pins are an ABI compatibility matrix verified on the 3.9 floor — see the comment block in pyproject.toml.

Layout

CTO-MCP/
├── persona_constitution/
│   ├── __init__.py          Package API re-exports
│   ├── scanner.py           Detection engine: CodebaseCSI + prose rules + Python AST
│   ├── ast_bridge.py        constitution-xast: tree-sitter engine for brace languages
│   ├── logic_rules.py       Deep logic rules: Po10 metrics, empty loops, identical
│   │                        branches, constant conditions, unreachable code
│   ├── server.py            MCP server: JSON-RPC 2.0 over stdio
│   ├── review/
│   │   ├── diff.py          Unified diff parser (git-quoted paths, hunk edge cases)
│   │   ├── engine.py        Diff-aware review: attribution, C-03 policy, exclusions
│   │   ├── config.py        .persona-review.json: one policy for both gate factors
│   │   ├── report.py        Renderers: text, Actions annotations, GitHub review payload
│   │   ├── github_client.py Stdlib GitHub REST client (bounded retries)
│   │   └── cli.py           persona-pr-review: --staged/--diff/--git/--github/--install-hook
│   └── data/                Ships inside the package, so an installed copy works
│       ├── CONSTITUTION.md  Full constitution (the served corpus)
│       └── DIRECTIVES.md    Distilled directives for system-prompt injection
├── codebase_csi/            Vendored CodebaseCSI (MIT) — see VENDORED.md
├── .persona-review.json     This repository's own review policy (dogfood)
├── .opencode/
│   ├── agent/pr-review.md   Factor-2 agent: business-logic test research + G1-G5
│   └── command/review-staged.md  /review-staged: both factors before committing
├── .github/workflows/
│   ├── ci.yml               Lint, tests (3.9/3.14 x with/without [ast]), packaging
│   └── pr-review.yml        Dogfood: this repo's PRs pass through its own gate
├── action.yml               Reusable composite GitHub Action for any repository
├── tests/                   Unit, engine, review, two-factor integration, smoke, e2e
├── tools/
│   └── benchmark_scanner.py Adversarial accuracy benchmark (regression gate)
├── LICENSE
├── pyproject.toml
└── README.md

Setup

From the repo root:

python3 -m venv .venv
.venv/bin/pip install -e ".[ast]"   # or plain `.` to skip the tree-sitter tier

.venv/bin/python is then the interpreter your MCP client must launch. Starting the server with an interpreter that cannot import the vendored codebase_csi exits 1 with an explanatory message on stderr — it will not fall back to a weaker scanner and report misleadingly clean results.

Install into opencode

Two mechanisms, used together. The instructions file injects the constitution into the system prompt of every session, for every configured model; the MCP server provides on-demand structured lookup and mechanical verification.

Injection is not enforcement. instructions is system-prompt text, and whether a model follows it is a property of that model, not of this repo — only the MCP scanner performs a mechanical check. Two caveats worth knowing before you rely on it:

• Small-context models can choke on the payload. DIRECTIVES.md is a substantial system prompt; on a 16k-context deployment (tested: Azure Phi-4) sessions hung rather than degrading gracefully. Prefer models with a large context window, or trim DIRECTIVES.md for small ones.
• Compliance is per-model and worth spot-checking. Verified by direct observation on OpenAI- and Anthropic-adapter models, which reproduced gate and law text verbatim on request. That is a sample, not a proof across every provider — re-verify on yours.

Add to ~/.config/opencode/opencode.json (or opencode.jsonc), replacing <REPO> with the absolute path to this clone:

{
  "$schema": "https://opencode.ai/config.json",

  "instructions": ["<REPO>/persona_constitution/data/DIRECTIVES.md"],

  "mcp": {
    "persona-constitution": {
      "type": "local",
      "command": ["<REPO>/.venv/bin/python", "<REPO>/persona_constitution/server.py"],
      "enabled": true
    }
  }
}

instructions is global opencode config, so the directives are injected into the system prompt of every model and provider you have configured — there is no per-model setup. Note that the directives consume context: models with small context windows may struggle.

Restart opencode afterwards — config is loaded once at startup and is not hot-reloaded.

Install into other MCP clients

Any client that speaks MCP over stdio works. Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "persona-constitution": {
      "command": "<REPO>/.venv/bin/python",
      "args": ["<REPO>/persona_constitution/server.py"]
    }
  }
}

Tools

section values for get_constitution

toc · preamble · identity · anti-deception · intelligence-architecture · t-shape · swebok · consensus-protocol · iteration-protocol · agentic-pathway · power-of-10 · operational-directives · knowledge-graph · invariants · references · full

(hive-mind is still accepted as a deprecated alias for consensus-protocol.)

The scanner

scan_code_for_violations is a union of five engines, because no one of them is adequate alone:

Verdict philosophy: mechanical certainties (stubs, scaffold markers) are violations and FAIL; judgement calls (metrics, logic shape, test presence) are warnings and REVIEW - the agent layer adjudicates them, never silently.

Coverage by failure class:

• Class 1 — Framework Generation: TODO, FIXME, XXX, "your code here", "implement … here/later", raise NotImplementedError, todo!(), unimplemented!(), panic("not implemented"), empty function and method bodies, and bodies consisting only of pass or ...
• Class 2 — Scaffold Deception: "rest of the implementation", "follows the same pattern", "omitted for brevity", "and so on for the rest", "similar for the others"
• Class 3 — Confidence Mismatch: empty catch {} blocks, bare except: pass, always-success functions
• Class 5 — Iteration Deferral: "left as an exercise", "you can extend this", "this is a starting point", "you would want to add", "the full implementation would", "in production you would"

Verdicts: FAIL if any violation fires, REVIEW if only warnings fire, PASS otherwise.

Measured accuracy

Measured against a 37-case adversarial corpus — 24 real violations across seven languages, plus 13 pieces of legitimate code specifically constructed to resemble violations (a linter that matches on the string "TODO", a typing.Protocol whose methods are ..., a documented except OSError: pass, a React placeholder= attribute, an anonymous no-op callback, an empty Java constructor, a noop-default arrow binding, a busy-wait loop):

The engines fail on largely disjoint inputs, which is why the union beats each: CodebaseCSI misses every non-Python structural stub and every prose deferral; the prose rules miss Python-semantic stubs such as always-true and print-only functions; and seven corpus cases (function getUser(id) { return null; }, a bare UnsupportedOperationException, a template-literal throw new Error(`not implemented`), a braceless empty Ruby method, a Go return nil stub, and stubs bound through const name = (args) => {...} declarators) are decidable only on a real syntax tree. Both baselines are enforced in CI across both configurations.

Reproduce with:

.venv/bin/python tools/benchmark_scanner.py

Read these numbers with suspicion. The corpus is small and was written by the same author as the rules, which biases the result upward. It is a regression guard, not a general accuracy claim.

A PASS is necessary but not sufficient. Static analysis proves the absence of placeholder markers — it cannot prove executability, correctness, or dependency honesty. The G1–G5 gates still apply.

Two-factor review

The scanner generalises to a two-factor review gate through persona_constitution/review/: the same deterministic engine judges the change at two moments — factor 1a when files are staged (pre-commit hook, contents read from the git index so what is judged is exactly what would be committed) and factor 1b at PR time (Action / CLI / MCP tool). Factor 2 is the agent layer, which at both moments researches the project's business-logic tests before exercising judgement. Findings are attributed to the lines the change introduces; pre-existing debt in touched files is counted and surfaced but never gates the merge.

One policy file, .persona-review.json at the repository root, drives every surface (both factors, the Action, and the agent), so a rule can never be enforced at one gate and forgotten at the other:

{
  "exclude": ["tests/*", "vendor/*"],
  "require_tests": "warn",
  "min_test_trigger_lines": 5,
  "test_globs": ["qa/*"],
  "business_logic": {
    "description": "what this system's correctness actually means",
    "critical_paths": ["billing/*"],
    "business_logic_tests": ["tests/test_billing.py"],
    "test_commands": ["python -m unittest discover -s tests"]
  }
}

require_tests is the C-03 policy (non-trivial code ships with tests): when a diff changes at least min_test_trigger_lines of production logic and touches zero test files, every such file is flagged — warn surfaces it for adjudication, fail gates the merge. The deterministic policy is deliberately diff-global; mapping which tests cover which changed behaviour is the agent's business-logic research, not a glob matcher's.

Delivery surfaces, one engine:

0. Staged gate (factor 1a) — install once per clone:

persona-pr-review --install-hook          # writes .git/hooks/pre-commit (refuses to clobber
                                          # a foreign hook without --force)
persona-pr-review --staged --json         # what the hook runs: git diff --cached, contents
                                          # from `git show :0:path` (the index, not the worktree)

A commit with staged violations is blocked; bypassing with git commit --no-verify is loud and still lands in front of factor 1b and the agent.

1. MCP tool — review_patch (table above). The server stays offline and deterministic: the agent brings the diff (gh pr diff), the tool returns structured findings.

2. CLI — installed as persona-pr-review:

# local working tree against a base
persona-pr-review --git origin/main...HEAD --root . --json

# an existing diff file, annotated for GitHub Actions
persona-pr-review --diff change.diff --annotate

# a GitHub PR, posting REQUEST_CHANGES/COMMENT with inline comments
GITHUB_TOKEN=... persona-pr-review --github owner/repo#42 --post \
    --require-tests fail --exclude 'vendor/*'

Flags override .persona-review.json; --exclude appends to it. Exit codes: 0 PASS (or REVIEW), 1 FAIL (or REVIEW with --fail-on-review), 3 operational error (including a malformed policy file — a broken policy stops the gate rather than silently weakening it). The GitHub client is stdlib urllib with bounded retries; the reviewer never emits APPROVE — a scanner can prove the absence of markers, not the presence of correctness.

3. Reusable GitHub Action — the composite action at the repo root:

permissions:
  contents: read
  pull-requests: write
steps:
  - uses: actions/checkout@v5
  - uses: QuantmindSSI/CTO-MCP@main   # pin a tag/sha in production
    with:
      exclude: "vendor/*"        # appended to the repo's .persona-review.json
      require-tests: "warn"      # C-03; empty = use the repo's config
      fail-on-review: "false"

Violations become ::error annotations on the changed lines and a posted review that REQUEST_CHANGES; fork PRs are automatically downgraded to annotations-only so the token never serves untrusted code. This repository dogfoods the action on its own PRs (.github/workflows/pr-review.yml).

4. opencode agent (factor 2) — .opencode/agent/pr-review.md defines the agentic layer. Its protocol is layered and ordered: Layer 0 reads .persona-review.json and researches the project's test landscape (which layers exist — unit, integration, e2e, smoke, regression — and which tests reference the changed symbols, via git grep over the test tree); Layer 1 runs the deterministic gate through the MCP tool (its FAIL verdict cannot be overridden); Layer 2 judges business-logic coverage — changed behaviour vs. covering tests found, updated or not, with test-command runs as evidence; Layer 3 applies gates G1–G5 and the nine review dimensions. Deterministic findings are supreme; agent judgement is additive only; never APPROVE.

5. /review-staged command — .opencode/command/review-staged.md runs the full two-factor flow on the staged index before a commit: the deterministic staged gate first, then the same agent protocol, concluding "COMMIT" or "DO NOT COMMIT" with file:line-anchored required fixes.

The five verification gates

Run before emitting any code. All five must pass; if any fails, regenerate from the problem statement rather than patching.

Configuration

The server exits with status 1 and a message on stderr if the constitution file is missing or empty — a broken install fails loudly rather than silently serving nothing.

Tests

Run from the repo root, using the virtualenv interpreter:

.venv/bin/python -m unittest discover -s tests -v
.venv/bin/python tools/benchmark_scanner.py          # regression gate

The suite is organised as a full test taxonomy:

1. Smoke (test_smoke.py) — the critical path of every delivery surface in seconds: package import and version coherence, one stub/one clean scan, one review verdict, the console entry point, and a real MCP stdio handshake listing all six tools. A broken install fails here before anything else spends time.
2. Unit (test_server.py, test_ast_bridge.py) — constitution loading, markdown section extraction (all 14 sections, 18 KAs, 10 rules), scanner line-number accuracy and verdict boundaries, JSON-RPC dispatch, per-language xast stub detection, the deep-logic rules (Po10 metrics, empty loops, identical branches, constant conditions, unreachable code, while True: exemption), and the constant-drift guards that keep cross-engine deduplication sound.
3. Regression (test_server.py false-positive classes, tools/benchmark_scanner.py) — every previously confirmed false positive stays fixed (string literals, Protocol, @abstractmethod, documented except: pass, {} literals inside Python bodies, triple-quote parity), and the 37-case adversarial corpus enforces environment-aware accuracy baselines (37/37 with [ast], 30/37 without) in CI.
4. Review engine (test_review.py) — diff parsing (renames, binary, git-quoted unicode paths, submodule and mode-only changes, CRLF, lying hunk headers, adversarial garbage), changed-line attribution vs. pre-existing debt, exclusion globs, renderer contracts (never APPROVE, comment budgets, annotation escaping), and the review_patch tool over the dispatcher including C-03 arguments.
5. Two-factor integration (test_two_factor.py) — real git repositories: the policy config contract (strict schema, loud failures), C-03 test-presence enforcement in warn/fail modes, staged-gate index authority (a fixed worktree must not mask a broken index), hook installation (foreign-hook refusal, --force), an installed hook blocking a genuine git commit and then admitting a clean, tested change, and factor parity (staged gate and PR gate reach identical findings on the same change).
6. End-to-end transport (test_server.py) — a real subprocess driven over stdio: initialize handshake, tools/list, a full multi-tool session, malformed-input recovery, notification suppression, non-zero exit on a missing data file, and the invariant that stdout carries only protocol frames.

Protocol notes

• Transport: newline-delimited JSON-RPC 2.0 over stdio, one message per line.
• Methods: initialize, tools/list, tools/call, ping. notifications/* are accepted and correctly produce no response frame.
• Protocol version: 2025-06-18; the client's requested version is echoed when it supplies one.
• Tool-level failures (bad arguments) return isError: true inside the result so the model can read and self-correct. Protocol-level failures return proper JSON-RPC error codes (-32700, -32600, -32601, -32602, -32603).
• Diagnostics go to stderr exclusively. stdout is never polluted with non-protocol bytes.

Credits

The structural detection layer of the scanner is provided by CodebaseCSI, used under the MIT License and vendored at codebase_csi/ (upstream revision and local modifications are recorded in codebase_csi/VENDORED.md). This project adds the MCP interface, the Constitution corpus, the Class 2 / Class 5 prose rules, the cross-language structural rules, the Python AST false-positive suppression, the tree-sitter xast engine, and the diff-aware PR review stack.

License

MIT — see LICENSE.

CodebaseCSI is also MIT, and its license text is reproduced verbatim in the LICENSE file under Third-Party Components, as its terms require.

References

1. IEEE Computer Society (2024). Guide to the Software Engineering Body of Knowledge (SWEBOK) v4.0. Ed. H. Washizaki. 18 Knowledge Areas.
2. Holzmann, G.J. (2006). The Power of 10: Rules for Developing Safety-Critical Code. IEEE Computer 39(6), 95–97.
3. Model Context Protocol specification — https://modelcontextprotocol.io
4. CodebaseCSI — forensic AI-generated-code detection. https://github.com/Thundastormgod/CodebaseCSI