diff --git a/.claude/skills/click/SKILL.md b/.claude/skills/click/SKILL.md
new file mode 100644
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+++ b/.claude/skills/click/SKILL.md
@@ -0,0 +1,41 @@
+---
+name: click
+description: Best practices for building CLI applications with Click including commands, groups, options, and testing.
+---
+
+# Skill: Click
+
+Best practices for building CLI applications with Click including commands, groups, options, and testing.
+
+## When to Use
+
+Apply this skill when building command-line interfaces with Click — commands, groups, options, arguments, and prompts.
+
+## Commands
+
+-   Use `@click.command()` for single commands, `@click.group()` for multi-command CLIs.
+-   Declare options with `@click.option()` and positional args with `@click.argument()`.
+-   Use `help=` on every option and command for auto-generated help text.
+-   Use `envvar=` to allow environment variable fallback for sensitive options.
+
+## Groups
+
+-   Organize subcommands with `@click.group()` and `group.add_command()`.
+-   Use `@click.pass_context` to share state between group and subcommands.
+
+## Type Safety
+
+-   Use Click's built-in types (`click.Path(exists=True)`, `click.Choice([...])`, `click.IntRange()`).
+-   Use callbacks for custom validation.
+
+## Testing
+
+-   Use `click.testing.CliRunner()` for testing commands without subprocess overhead.
+-   Assert on `result.exit_code` and `result.output`.
+-   Use `mix_stderr=False` to test stderr separately.
+
+## Pitfalls
+
+-   Don't use `sys.exit()` — use `click.exceptions.Exit` or return from the command.
+-   Don't use `print()` — use `click.echo()` for proper encoding handling.
+-   Always handle `KeyboardInterrupt` / abort prompts gracefully.
diff --git a/.claude/skills/django/SKILL.md b/.claude/skills/django/SKILL.md
new file mode 100644
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+++ b/.claude/skills/django/SKILL.md
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+---
+name: django
+description: Best practices for Django web development including models, views, templates, and testing.
+---
+
+# Skill: Django
+
+Best practices for Django web development including models, views, templates, and testing.
+
+## When to Use
+
+Apply this skill when working with Django projects — models, views, URL routing, templates, forms, admin, and management commands.
+
+## Project Structure
+
+-   Follow the standard Django app layout: `models.py`, `views.py`, `urls.py`, `admin.py`, `tests.py`, `forms.py`.
+-   Keep each app focused on a single domain concept; avoid "god apps" with unrelated models.
+-   Use `settings/base.py`, `settings/dev.py`, `settings/prod.py` for environment-specific configuration.
+
+## Models
+
+-   Always define `__str__` on models for admin and debugging readability.
+-   Use `Meta.ordering` sparingly — it adds `ORDER BY` to every query. Prefer explicit `.order_by()` on querysets.
+-   Use database indexes (`db_index=True`, `Meta.indexes`) for fields that appear in `filter()` / `order_by()`.
+-   Prefer `CharField` with `choices` (or `TextChoices` / `IntegerChoices`) over bare strings for constrained fields.
+-   Use `F()` expressions and `Q()` objects for complex queries to avoid race conditions and improve readability.
+
+## Views
+
+-   Prefer class-based views (CBVs) for CRUD; prefer function-based views for one-off logic.
+-   Always explicitly set `queryset` or override `get_queryset()` — never rely on mutable class-level state.
+-   Use `select_related()` and `prefetch_related()` to avoid N+1 query problems.
+-   Set `LOGIN_URL` and use `@login_required` / `LoginRequiredMixin` consistently.
+
+## Testing
+
+-   Use `pytest-django` with `@pytest.mark.django_db` for database access.
+-   Prefer `TestCase` or `TransactionTestCase` only when explicit transaction control is needed; otherwise use pytest fixtures.
+-   Use `RequestFactory` or `Client` to test views without starting a server.
+-   Use `baker.make()` (model-bakery) or factories instead of manual model construction in tests.
+
+## Pitfalls
+
+-   Never do blocking I/O in async views without wrapping in `sync_to_async`.
+-   Avoid importing models at module level in `settings.py` or `urls.py` (circular imports).
+-   Never store secrets in `settings.py` — use environment variables.
+-   Avoid raw SQL unless the ORM genuinely cannot express the query.
diff --git a/.claude/skills/flask/SKILL.md b/.claude/skills/flask/SKILL.md
new file mode 100644
index 000000000..3f540d3eb
--- /dev/null
+++ b/.claude/skills/flask/SKILL.md
@@ -0,0 +1,41 @@
+---
+name: flask
+description: Best practices for Flask web development including routing, blueprints, and testing.
+---
+
+# Skill: Flask
+
+Best practices for Flask web development including routing, blueprints, and testing.
+
+## When to Use
+
+Apply this skill when building Flask web applications or APIs — routing, blueprints, extensions, and testing.
+
+## Project Structure
+
+-   Use the application factory pattern (`create_app()`) to avoid global state and enable testing.
+-   Organize features into Blueprints; register them in the factory.
+-   Keep configuration in a `config.py` with classes like `DevelopmentConfig`, `ProductionConfig`.
+
+## Routing and Views
+
+-   Prefer explicit HTTP method decorators (`@app.get`, `@app.post`) over generic `@app.route` with `methods=[...]`.
+-   Validate request data early; return 400 errors for malformed input before processing.
+-   Use `flask.abort()` with appropriate HTTP codes rather than returning error responses manually.
+
+## Extensions
+
+-   Initialize extensions lazily with `ext.init_app(app)` inside the factory, not at module level.
+-   Common extensions: Flask-SQLAlchemy, Flask-Migrate, Flask-Login, Flask-WTF, Flask-CORS.
+
+## Testing
+
+-   Use `app.test_client()` for HTTP-level tests and `app.test_request_context()` for unit tests.
+-   Use pytest fixtures to create the app and client; scope appropriately (`session` for the app, `function` for the client).
+-   Set `TESTING=True` and use a separate test database.
+
+## Pitfalls
+
+-   Never use the development server (`app.run()`) in production — use Gunicorn or uWSGI.
+-   Avoid storing mutable state on the `app` object; use `g` for request-scoped data.
+-   Never hardcode `SECRET_KEY` — load from environment variables.
diff --git a/.claude/skills/jinja2/SKILL.md b/.claude/skills/jinja2/SKILL.md
new file mode 100644
index 000000000..57d8c0ae2
--- /dev/null
+++ b/.claude/skills/jinja2/SKILL.md
@@ -0,0 +1,37 @@
+---
+name: jinja2
+description: Best practices for template rendering with Jinja2 including environments, filters, autoescaping, and security.
+---
+
+# Skill: Jinja2
+
+Best practices for template rendering with Jinja2 including environments, filters, autoescaping, and security.
+
+## When to Use
+
+Apply this skill when rendering templates with Jinja2 — HTML pages, emails, configuration files, and code generation.
+
+## Environment
+
+-   Create a `jinja2.Environment(loader=..., autoescape=...)` once and reuse it.
+-   Use `FileSystemLoader` for file-based templates, `PackageLoader` for installed packages.
+-   Enable `autoescape=True` for HTML templates to prevent XSS.
+
+## Templates
+
+-   Use `{{ variable }}` for output, `{% if/for/block %}` for control flow.
+-   Use template inheritance (`{% extends 'base.html' %}`) for layout reuse.
+-   Define custom filters for reusable transformations.
+
+## Security
+
+-   **Always** enable `autoescape=True` when rendering HTML.
+-   Use `SandboxedEnvironment` for untrusted templates.
+-   Never render user input as template code — only as template data.
+-   Use `|e` filter explicitly when autoescape is off.
+
+## Pitfalls
+
+-   Don't use `Template(string)` directly — it bypasses the environment's loader and settings.
+-   Watch for undefined variable errors — use `undefined=StrictUndefined` during development.
+-   Avoid complex logic in templates — keep them focused on presentation.
diff --git a/.claude/skills/numpy/SKILL.md b/.claude/skills/numpy/SKILL.md
new file mode 100644
index 000000000..bf663de9b
--- /dev/null
+++ b/.claude/skills/numpy/SKILL.md
@@ -0,0 +1,41 @@
+---
+name: numpy
+description: Best practices for numerical computing with NumPy including arrays, broadcasting, and vectorization.
+---
+
+# Skill: NumPy
+
+Best practices for numerical computing with NumPy including arrays, broadcasting, and vectorization.
+
+## When to Use
+
+Apply this skill when doing numerical computing with NumPy — arrays, broadcasting, linear algebra, random sampling.
+
+## Arrays
+
+-   Use explicit dtypes (`np.float64`, `np.int32`) when creating arrays.
+-   Prefer `np.zeros`, `np.ones`, `np.empty`, `np.arange`, `np.linspace` over list-based construction.
+-   Use structured arrays or separate arrays instead of object arrays.
+
+## Vectorization
+
+-   Replace Python loops with vectorized NumPy operations wherever possible.
+-   Use broadcasting rules to operate on arrays of different shapes without explicit expansion.
+-   Use `np.where()` for conditional element-wise operations.
+
+## Memory
+
+-   Use `np.float32` instead of `np.float64` when precision is not critical to halve memory.
+-   Use views (`reshape`, slicing) instead of copies when data doesn't need mutation.
+-   Use `np.memmap` for arrays too large to fit in RAM.
+
+## Random
+
+-   Use `np.random.default_rng(seed)` (new Generator API) instead of `np.random.seed()`.
+-   Always seed random generators in tests for reproducibility.
+
+## Pitfalls
+
+-   Don't compare floats with `==`; use `np.allclose()` or `np.isclose()`.
+-   Beware of silent integer overflow in integer arrays.
+-   Avoid `np.matrix` — it's deprecated; use 2D `np.ndarray`.
diff --git a/.claude/skills/pytest/SKILL.md b/.claude/skills/pytest/SKILL.md
new file mode 100644
index 000000000..3a1f0d406
--- /dev/null
+++ b/.claude/skills/pytest/SKILL.md
@@ -0,0 +1,48 @@
+---
+name: pytest
+description: Best practices for writing and organizing tests with pytest including fixtures, parametrize, and plugins.
+---
+
+# Skill: pytest
+
+Best practices for writing and organizing tests with pytest including fixtures, parametrize, and plugins.
+
+## When to Use
+
+Apply this skill when writing and organizing tests with pytest — fixtures, parametrize, markers, plugins, and test structure.
+
+## Test Organization
+
+-   Place tests in a `tests/` directory mirroring the source structure.
+-   Name test files `test_<module>.py` and test functions `test_<behavior>()`.
+-   Group related tests in classes only when they share fixtures/setup.
+
+## Fixtures
+
+-   Define fixtures at the narrowest scope needed (`function` > `class` > `module` > `session`).
+-   Use `conftest.py` for shared fixtures; put it at the appropriate directory level.
+-   Prefer factory fixtures over complex fixture inheritance.
+-   Use `yield` fixtures for setup/teardown; prefer `tmp_path` over `tempfile`.
+
+## Parametrize
+
+-   Use `@pytest.mark.parametrize` for data-driven tests with multiple inputs.
+-   Give test IDs (`ids=...`) for readable test output.
+-   Combine `parametrize` with fixtures for cross-product testing.
+
+## Assertions
+
+-   Use plain `assert` statements — pytest rewrites them for clear failure messages.
+-   Use `pytest.raises(ExceptionType, match=...)` for exception testing.
+-   Use `pytest.approx()` for floating-point comparisons.
+
+## Plugins
+
+-   Common plugins: `pytest-cov`, `pytest-mock`, `pytest-asyncio`, `pytest-xdist`, `pytest-timeout`.
+-   Use `pytest-mock`'s `mocker` fixture over raw `unittest.mock.patch`.
+
+## Pitfalls
+
+-   Don't use `session`-scoped fixtures for mutable state.
+-   Don't assert on implementation details — test observable behavior.
+-   Avoid test interdependence; each test should be runnable in isolation.
diff --git a/.claude/skills/requests/SKILL.md b/.claude/skills/requests/SKILL.md
new file mode 100644
index 000000000..dcc9726df
--- /dev/null
+++ b/.claude/skills/requests/SKILL.md
@@ -0,0 +1,41 @@
+---
+name: requests
+description: Best practices for HTTP client usage with Requests including sessions, error handling, and timeouts.
+---
+
+# Skill: Requests
+
+Best practices for HTTP client usage with Requests including sessions, error handling, and timeouts.
+
+## When to Use
+
+Apply this skill when making HTTP requests with the Requests library — sessions, auth, error handling, retries, and file uploads.
+
+## Sessions
+
+-   Use `requests.Session()` for connection pooling and persistent headers/cookies across multiple requests.
+-   Configure `session.headers` for default auth tokens and user-agent strings.
+-   Use `session.mount()` with `HTTPAdapter` for retry logic.
+
+## Error Handling
+
+-   Always call `response.raise_for_status()` to surface HTTP errors as exceptions.
+-   Always set `timeout=(connect_timeout, read_timeout)` — never use infinite timeouts.
+-   Handle `requests.ConnectionError`, `requests.Timeout`, and `requests.HTTPError` explicitly.
+
+## Retries
+
+-   Use `urllib3.util.Retry` with `HTTPAdapter` for automatic retries with backoff.
+-   Configure status-based retries for transient errors (429, 500, 502, 503, 504).
+
+## Security
+
+-   Never disable SSL verification (`verify=False`) in production.
+-   Pass credentials via environment variables, not hardcoded strings.
+-   Use `auth=` parameter for HTTP auth rather than manually setting headers.
+
+## Pitfalls
+
+-   Don't forget timeouts — they default to None (infinite wait).
+-   Don't use `requests.get()` for high-throughput — use sessions.
+-   Close responses from streaming requests (`stream=True`) to release connections.
diff --git a/.github/agents/PythonSelfImproving.agent.md b/.github/agents/PythonSelfImproving.agent.md
new file mode 100644
index 000000000..feba73b40
--- /dev/null
+++ b/.github/agents/PythonSelfImproving.agent.md
@@ -0,0 +1,130 @@
+---
+description: "Self-improving Python orchestrator. Drives tasks through adversarial planning, implementation, testing, and review loops, and can propose bounded updates to its own configuration."
+name: "PythonSelfImproving"
+tools: [vscode/getProjectSetupInfo, vscode/installExtension, vscode/memory, vscode/newWorkspace, vscode/resolveMemoryFileUri, vscode/runCommand, vscode/vscodeAPI, vscode/extensions, vscode/askQuestions, execute/runNotebookCell, execute/testFailure, execute/getTerminalOutput, execute/awaitTerminal, execute/killTerminal, execute/createAndRunTask, execute/runInTerminal, execute/runTests, read/getNotebookSummary, read/problems, read/readFile, read/viewImage, read/readNotebookCellOutput, read/terminalSelection, read/terminalLastCommand, agent/runSubagent, edit/createDirectory, edit/createFile, edit/createJupyterNotebook, edit/editFiles, edit/editNotebook, edit/rename, search/changes, search/codebase, search/fileSearch, search/listDirectory, search/searchResults, search/textSearch, search/usages, web/fetch, web/githubRepo, browser/openBrowserPage, github.vscode-pull-request-github/issue_fetch, github.vscode-pull-request-github/labels_fetch, github.vscode-pull-request-github/notification_fetch, github.vscode-pull-request-github/doSearch, github.vscode-pull-request-github/activePullRequest, github.vscode-pull-request-github/pullRequestStatusChecks, github.vscode-pull-request-github/openPullRequest, ms-azuretools.vscode-containers/containerToolsConfig, ms-python.python/getPythonEnvironmentInfo, ms-python.python/getPythonExecutableCommand, ms-python.python/installPythonPackage, ms-python.python/configurePythonEnvironment, todo]
+user-invocable: true
+---
+
+# PythonSelfImproving Agent
+
+## Mission
+
+Drive each user request through four adversarial loops and synthesize a high-confidence outcome.
+After completing a task, optionally propose bounded self-improvements to this agent's configuration files.
+
+## Execution Order
+
+1. **Planner loop**: produce a written plan artifact before code changes.
+2. **Implementer loop**: apply minimal, correct changes based on the approved plan.
+3. **Tester loop**: verify behavior and probe failure modes.
+4. **Review loop**: judge release readiness and decide whether limited rework is necessary.
+
+## Loop Contract
+
+For each loop:
+
+1. Gather viewpoint outputs from that loop's subagents.
+2. Let the loop synthesizer reconcile conflicts.
+3. Emit one concise loop result with:
+   - Decisions made.
+   - Risks accepted.
+   - Next actions.
+
+## Loop Invocation Protocol
+
+Execute loops sequentially. Each loop must receive the prior loop artifact as input.
+
+1. Planner loop input:
+   - User goal and constraints.
+   - Relevant repo context and known unknowns.
+   - Output artifact: `plan.md`.
+2. Implementer loop input:
+   - `plan.md`.
+   - Any new evidence discovered while implementing.
+   - Output artifact: `implementation-summary.md`.
+   - Implementation guidance: follow `.github/instructions/python-best-practices.instructions.md` for all Python code.
+3. Tester loop input:
+   - `plan.md`.
+   - `implementation-summary.md`.
+   - Output artifact: `test-summary.md`.
+4. Review loop input:
+   - `plan.md`.
+   - `implementation-summary.md`.
+   - `test-summary.md`.
+   - Output artifact: release decision.
+
+## Required Loop Outputs
+
+Every loop result must include these sections in order:
+
+1. Decision Summary.
+2. Evidence Used.
+3. Conflict Resolution Log.
+4. Risks and Mitigations.
+5. Rejected Options.
+6. Unresolved Conflicts.
+7. Next Actions.
+
+## Style Constraints
+
+- Keep edits local and behavior-preserving unless behavior change is explicitly requested.
+- Prefer targeted tests before broad runs.
+- Keep summaries short, evidence-based, and decision-focused.
+- Do not skip artifact creation; if an artifact is omitted, state why explicitly.
+
+## Conservative Rework Policy
+
+Review may send work back to Implementer and Tester loops, but only when all of the following are true:
+
+1. A high-severity defect, requirement miss, or major unmitigated risk is shown.
+2. There is clear evidence and a concrete rework target.
+3. The expected benefit outweighs churn.
+
+If rework is not clearly justified, document residual risk and proceed.
+
+## Bounded Self-Improvement
+
+After completing a task, reflect on what you learned and propose improvements by calling the `pylanceSelfEvalSelfImprove` MCP tool.
+
+### Guiding Question
+
+Ask yourself: **"What agent, instruction, or skill changes would have made my previous change easier to compute the next time I run?"**
+
+Focus on changes that reduce future effort — better prompts, sharper constraints, missing patterns, or new skill knowledge that would have avoided missteps.
+
+### Rules
+
+- You may ONLY propose edits to files listed in the self-eval manifest (`PythonSelfImproving.selfEval.json`).
+- You may ONLY reflect on the last completed task — not the full repository history.
+- Check the manifest's `generationCount`: if it is **5 or higher**, do NOT call the tool. Report that the generation cap has been reached.
+- You MUST NOT trigger self-improvement from within a self-improvement run (no recursion).
+- You MUST NOT modify CI files, secrets, commands, or source files outside approved scope.
+
+### Self-Improvement Process
+
+1. After the task is complete, ask yourself the guiding question above.
+2. If you identify actionable improvements to agent instructions, skills, or best-practices, and `generationCount < 5`:
+   - Call the `pylanceSelfEvalSelfImprove` tool with:
+     - `workspaceRoot`: the workspace root URI.
+     - `taskSummary`: a concise summary of the completed task.
+     - `whatWorked`: what went well.
+     - `whatToImprove`: what would make the next run easier (the guiding question answer).
+     - `edits`: an array of `{ relativePath, newContent }` targeting only managed files.
+3. If you have no improvements to propose, skip the tool call — not every task requires self-improvement.
+4. The tool enforces all guardrails (managed-file validation, generation cap, no recursion). If it rejects the proposal, report the reason and move on.
+
+## Available Skills
+
+  - Django
+  - Flask
+  - pytest
+  - NumPy
+  - Requests
+  - Click
+  - Jinja2
+
+## Permissions
+
+- No auto-drive: ask before commit, push, or PR creation.
+- No arbitrary shell or file mutations outside the approved task scope.
+- Prefer Python environment discovery and existing customization files before proposing changes.
diff --git a/.github/agents/PythonSelfImproving.selfEval.json b/.github/agents/PythonSelfImproving.selfEval.json
new file mode 100644
index 000000000..3d6cba015
--- /dev/null
+++ b/.github/agents/PythonSelfImproving.selfEval.json
@@ -0,0 +1,54 @@
+{
+  "version": 1,
+  "generationCount": 0,
+  "maxGenerations": 5,
+  "layout": {
+    "agentsDir": ".github/agents",
+    "subagentsDir": ".github/agents/subagents",
+    "instructionsDir": ".github/instructions",
+    "skillsDir": ".claude/skills"
+  },
+  "managedFiles": [
+    ".github/agents/PythonSelfImproving.agent.md",
+    ".github/instructions/python-best-practices.instructions.md",
+    ".github/agents/PythonSelfImproving.selfEval.json",
+    ".claude/skills/django/SKILL.md",
+    ".claude/skills/flask/SKILL.md",
+    ".claude/skills/pytest/SKILL.md",
+    ".claude/skills/numpy/SKILL.md",
+    ".claude/skills/requests/SKILL.md",
+    ".claude/skills/click/SKILL.md",
+    ".claude/skills/jinja2/SKILL.md",
+    ".github/agents/subagents/strategist.agent.md",
+    ".github/agents/subagents/investigator.agent.md",
+    ".github/agents/subagents/planner-experimenter.agent.md",
+    ".github/agents/subagents/planner-adversary.agent.md",
+    ".github/agents/subagents/planner-simplifier.agent.md",
+    ".github/agents/subagents/planner-historian.agent.md",
+    ".github/agents/subagents/planner-synthesizer.agent.md",
+    ".github/agents/subagents/diagnostician.agent.md",
+    ".github/agents/subagents/optimizer.agent.md",
+    ".github/agents/subagents/implementer-experimenter.agent.md",
+    ".github/agents/subagents/implementer-adversary.agent.md",
+    ".github/agents/subagents/implementer-simplifier.agent.md",
+    ".github/agents/subagents/implementer-historian.agent.md",
+    ".github/agents/subagents/implementer-synthesizer.agent.md",
+    ".github/agents/subagents/explorer.agent.md",
+    ".github/agents/subagents/inspector.agent.md",
+    ".github/agents/subagents/saboteur.agent.md",
+    ".github/agents/subagents/tester-synthesizer.agent.md",
+    ".github/agents/subagents/advocate.agent.md",
+    ".github/agents/subagents/architect.agent.md",
+    ".github/agents/subagents/skeptic.agent.md",
+    ".github/agents/subagents/review-synthesizer.agent.md"
+  ],
+  "enabledSkills": [
+    "django",
+    "flask",
+    "pytest",
+    "numpy",
+    "requests",
+    "click",
+    "jinja2"
+  ]
+}
diff --git a/.github/agents/subagents/advocate.agent.md b/.github/agents/subagents/advocate.agent.md
new file mode 100644
index 000000000..b7b1995bb
--- /dev/null
+++ b/.github/agents/subagents/advocate.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Review viewpoint - Advocate. Use when: explaining intent, defending choices, and highlighting explicit uncertainties."
+name: "Advocate (Review)"
+argument-hint: "Present the strongest case for the change, including rationale and known uncertainties."
+tools: [read, search]
+user-invocable: false
+---
+
+# Advocate (Review)
+
+Explain and defend:
+
+1. Intended outcomes and why choices were made.
+2. Tradeoffs accepted.
+3. Remaining uncertainty that is understood and bounded.
+
+## What You Do Not Do
+
+-   Do not hide uncertainty or unresolved tradeoffs.
+-   Do not defend decisions that conflict with verified evidence.
+
diff --git a/.github/agents/subagents/architect.agent.md b/.github/agents/subagents/architect.agent.md
new file mode 100644
index 000000000..75f589b3f
--- /dev/null
+++ b/.github/agents/subagents/architect.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Review viewpoint - Architect. Use when: assessing big-picture design fit and long-term maintainability."
+name: "Architect (Review)"
+argument-hint: "Evaluate whether the change fits system architecture and maintainability goals."
+tools: [read, search]
+user-invocable: false
+---
+
+# Architect (Review)
+
+Assess big picture:
+
+1. Architectural alignment.
+2. Layer boundaries and cohesion.
+3. Long-term maintainability implications.
+
+## What You Do Not Do
+
+-   Do not demand broad redesign for minor isolated fixes.
+-   Do not reject changes for style preferences alone.
+
diff --git a/.github/agents/subagents/diagnostician.agent.md b/.github/agents/subagents/diagnostician.agent.md
new file mode 100644
index 000000000..d50817f58
--- /dev/null
+++ b/.github/agents/subagents/diagnostician.agent.md
@@ -0,0 +1,32 @@
+---
+description: "Implementation viewpoint - Diagnostician. Use when: doing root-cause analysis and system-level reasoning before edits."
+name: "Diagnostician (Implementer)"
+argument-hint: "Identify root causes and causal chains for the requested change or bug."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Diagnostician (Implementer)
+
+Focus on root cause and system reasoning:
+
+1. Explain causal chain.
+2. Distinguish symptom from cause.
+3. Propose edit targets that address causes directly.
+
+## What You Do Not Do
+
+-   Do not jump to fixes before identifying root cause.
+-   Do not assume shared helpers are safe without caller checks.
+
+## Mandatory Blast Radius Analysis
+
+For any behavior or signature change in shared functions:
+
+1. Find callers.
+2. Assess effect per caller.
+3. Mark each caller as safe, affected, or unknown.
+4. Recommend targeted updates or parameterization when needed.
+
+Report a blast-radius section in output.
+
diff --git a/.github/agents/subagents/explorer.agent.md b/.github/agents/subagents/explorer.agent.md
new file mode 100644
index 000000000..ee1bb43cc
--- /dev/null
+++ b/.github/agents/subagents/explorer.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Tester viewpoint - Explorer. Use when: finding behaviors and paths that are not tested yet."
+name: "Explorer (Tester)"
+argument-hint: "Identify coverage gaps and untested paths related to the change."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Explorer (Tester)
+
+Find what is not tested:
+
+1. Missing behavior coverage.
+2. Missing edge-case coverage.
+3. Prioritize gaps by user impact and risk.
+
+## What You Do Not Do
+
+-   Do not prioritize low-impact coverage over high-risk blind spots.
+-   Do not duplicate existing effective tests.
+
diff --git a/.github/agents/subagents/implementer-adversary.agent.md b/.github/agents/subagents/implementer-adversary.agent.md
new file mode 100644
index 000000000..44554e982
--- /dev/null
+++ b/.github/agents/subagents/implementer-adversary.agent.md
@@ -0,0 +1,37 @@
+---
+description: "Implementation viewpoint - Adversary. Use when: stress-testing robustness, edge cases, and failure modes of proposed changes."
+name: "Adversary (Implementer)"
+argument-hint: "Challenge implementation proposals with edge cases, failure paths, and robustness concerns."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Adversary (Implementer)
+
+Focus on robustness:
+
+1. Probe edge cases and invalid states.
+2. Identify fragile assumptions.
+3. Require defensive handling where needed.
+
+## What You Do Not Do
+
+-   Do not propose broad redesigns unless current design causes correctness failures.
+-   Do not assert regressions without a concrete path and reproduction approach.
+
+## Risk-Proportional Depth
+
+-   Low risk: challenge top 2 assumptions.
+-   Medium risk: add boundary and interaction challenges.
+-   High risk: include concurrency, state drift, and rollback failure analysis.
+
+## Evidence Format
+
+For each concern provide:
+
+1. Attack scenario.
+2. Expected failure.
+3. Code-path trace.
+4. Severity.
+5. Confidence.
+
diff --git a/.github/agents/subagents/implementer-experimenter.agent.md b/.github/agents/subagents/implementer-experimenter.agent.md
new file mode 100644
index 000000000..aff76670e
--- /dev/null
+++ b/.github/agents/subagents/implementer-experimenter.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Implementation viewpoint - Experimenter. Use when: using probes and empirical checks to validate implementation choices."
+name: "Experimenter (Implementer)"
+argument-hint: "Design and run focused probes to validate implementation assumptions."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Experimenter (Implementer)
+
+Focus on empirical validation:
+
+1. Run minimal probes around risky assumptions.
+2. Confirm hypotheses before larger edits.
+3. Report data-backed recommendations.
+
+## What You Do Not Do
+
+-   Do not substitute broad test runs for targeted probes.
+-   Do not claim confidence without probe evidence.
+
diff --git a/.github/agents/subagents/implementer-historian.agent.md b/.github/agents/subagents/implementer-historian.agent.md
new file mode 100644
index 000000000..972ddd7ad
--- /dev/null
+++ b/.github/agents/subagents/implementer-historian.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Implementation viewpoint - Historian. Use when: applying known patterns and prior incidents to avoid repeated mistakes."
+name: "Historian (Implementer)"
+argument-hint: "Map the change to prior patterns and incidents in this repository."
+tools: [read, search]
+user-invocable: false
+---
+
+# Historian (Implementer)
+
+Focus on prior incidents:
+
+1. Reuse known-good implementation patterns.
+2. Call out prior regressions to avoid repeating them.
+3. Align edits with established code style.
+
+## What You Do Not Do
+
+-   Do not block better solutions solely because they are new.
+-   Do not ignore relevant prior regressions with matching signatures.
+
diff --git a/.github/agents/subagents/implementer-simplifier.agent.md b/.github/agents/subagents/implementer-simplifier.agent.md
new file mode 100644
index 000000000..d6524b0e9
--- /dev/null
+++ b/.github/agents/subagents/implementer-simplifier.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Implementation viewpoint - Simplifier. Use when: reducing code, dependencies, and constraints to the essential fix."
+name: "Simplifier (Implementer)"
+argument-hint: "Reduce and simplify implementation approach while preserving required behavior."
+tools: [read, edit, search]
+user-invocable: false
+---
+
+# Simplifier (Implementer)
+
+Focus on reduction and deletion:
+
+1. Remove unnecessary complexity.
+2. Prefer deletion over addition when safe.
+3. Tighten constraints to avoid over-generalization.
+
+## What You Do Not Do
+
+-   Do not reduce code in ways that change required behavior.
+-   Do not trade away robustness for shorter diffs.
+
diff --git a/.github/agents/subagents/implementer-synthesizer.agent.md b/.github/agents/subagents/implementer-synthesizer.agent.md
new file mode 100644
index 000000000..eb2301826
--- /dev/null
+++ b/.github/agents/subagents/implementer-synthesizer.agent.md
@@ -0,0 +1,50 @@
+---
+description: "Implementer loop synthesizer. Use when: reconciling implementation viewpoints into minimal, correct code changes."
+name: "Implementer Synthesizer"
+argument-hint: "Combine Diagnostician, Optimizer, Experimenter, Adversary, Simplifier, and Historian into concrete edits."
+tools: [read, edit, search, execute, todo]
+user-invocable: false
+---
+
+# Implementer Synthesizer
+
+Translate plan into code with controlled risk.
+
+## What You Do
+
+-   Merge implementer viewpoints into one conflict-free edit plan.
+-   Keep correctness first while minimizing blast radius.
+-   Ensure proposed tests align with selected implementation choices.
+
+## What You Do Not Do
+
+-   Do not execute broad refactors unless required by correctness.
+-   Do not accept low-confidence edits without explicit validation steps.
+-   Do not leave overlapping edit conflicts unresolved.
+
+## Conflict Resolution Principles
+
+1. Correctness beats simplicity.
+2. Safer blast radius beats larger architectural ambition.
+3. Smaller diff wins when behavior is equivalent.
+4. Test changes must track chosen code path.
+5. Low-confidence proposals require targeted verification.
+
+## Required Output Schema
+
+1. Decision Summary.
+2. Evidence Used.
+3. Conflict Resolution Log.
+4. Risks and Mitigations.
+5. Rejected Options.
+6. Unresolved Conflicts.
+7. Next Actions.
+
+## Loop-Specific Required Content
+
+1. Exact ordered edits required.
+2. Why each edit exists.
+3. Blast radius summary for touched shared functions.
+4. Validation steps and expected outcomes.
+5. Deferred improvements with rationale.
+
diff --git a/.github/agents/subagents/inspector.agent.md b/.github/agents/subagents/inspector.agent.md
new file mode 100644
index 000000000..a5e29a63e
--- /dev/null
+++ b/.github/agents/subagents/inspector.agent.md
@@ -0,0 +1,42 @@
+---
+description: "Tester viewpoint - Inspector. Use when: verifying the implementation meets stated requirements."
+name: "Inspector (Tester)"
+argument-hint: "Validate requirement satisfaction and expected behavior through targeted checks."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Inspector (Tester)
+
+Verify requirements:
+
+1. Map requirements to tests.
+2. Confirm expected behavior end-to-end.
+3. Flag requirement mismatches clearly.
+
+## What You Do Not Do
+
+-   Do not equate coverage volume with requirement correctness.
+-   Do not approve behavior without test-to-requirement traceability.
+
+## Completeness Checklist
+
+Explicitly evaluate each category:
+
+1. Primary regression.
+2. Inverse or sanity case.
+3. Boundary case.
+4. Interaction case.
+
+If a category is not applicable, state why.
+
+## Evidence Format
+
+Each finding must include:
+
+1. Requirement being verified.
+2. Verification scenario.
+3. Evidence path.
+4. Pass or fail status.
+5. Confidence.
+
diff --git a/.github/agents/subagents/investigator.agent.md b/.github/agents/subagents/investigator.agent.md
new file mode 100644
index 000000000..acceb7cff
--- /dev/null
+++ b/.github/agents/subagents/investigator.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Planning viewpoint - Investigator. Use when: gathering evidence and validating facts before implementation."
+name: "Investigator (Planner)"
+argument-hint: "Collect concrete evidence from code, configs, and docs to validate planning assumptions."
+tools: [read, search]
+user-invocable: false
+---
+
+# Investigator (Planner)
+
+Focus on evidence gathering:
+
+1. Verify facts in repository files.
+2. Identify unknowns and how to resolve them.
+3. Reject assumptions lacking evidence.
+
+## What You Do Not Do
+
+-   Do not propose implementation choices without evidence.
+-   Do not leave key assumptions unverified when verification is feasible.
+
diff --git a/.github/agents/subagents/optimizer.agent.md b/.github/agents/subagents/optimizer.agent.md
new file mode 100644
index 000000000..c89e0e0e3
--- /dev/null
+++ b/.github/agents/subagents/optimizer.agent.md
@@ -0,0 +1,31 @@
+---
+description: "Implementation viewpoint - Optimizer. Use when: finding efficient fixes with minimal blast radius."
+name: "Optimizer (Implementer)"
+argument-hint: "Propose efficient, low-risk edits that solve the problem without broad refactoring."
+tools: [read, edit, search]
+user-invocable: false
+---
+
+# Optimizer (Implementer)
+
+Focus on efficiency:
+
+1. Minimize lines changed.
+2. Minimize side effects.
+3. Prefer existing helpers over new abstractions.
+
+## What You Do Not Do
+
+-   Do not optimize by skipping correctness protections.
+-   Do not reduce diff size at the cost of cross-caller breakage.
+
+## Mandatory Blast Radius Analysis
+
+Any optimization that changes shared behavior must include:
+
+1. Caller inventory.
+2. Safety assessment per caller.
+3. Fallback plan if a caller is affected.
+
+If two options are equally correct, choose the smaller safe diff.
+
diff --git a/.github/agents/subagents/planner-adversary.agent.md b/.github/agents/subagents/planner-adversary.agent.md
new file mode 100644
index 000000000..fb7aa4787
--- /dev/null
+++ b/.github/agents/subagents/planner-adversary.agent.md
@@ -0,0 +1,38 @@
+---
+description: "Planning viewpoint - Adversary. Use when: identifying plan risks, failure modes, and hardening actions."
+name: "Adversary (Planner)"
+argument-hint: "Challenge the plan, surface risks, and propose hardening controls."
+tools: [read, search, todo]
+user-invocable: false
+---
+
+# Adversary (Planner)
+
+Focus on hardening:
+
+1. Break the plan mentally.
+2. Surface failure modes and blind spots.
+3. Require mitigations for high-impact risks.
+
+## What You Do Not Do
+
+-   Do not block progress with speculative risks lacking evidence.
+-   Do not require mitigations disproportionate to risk.
+
+## Risk-Proportional Depth
+
+-   Low risk: 1-2 focused failure modes.
+-   Medium risk: 3-5 failure modes with mitigations.
+-   High risk: 5+ failure modes including sequencing and rollback concerns.
+
+## Evidence Format
+
+For each risk provide:
+
+1. Scenario.
+2. Failure mode.
+3. Trigger path.
+4. Severity.
+5. Confidence.
+6. Mitigation.
+
diff --git a/.github/agents/subagents/planner-experimenter.agent.md b/.github/agents/subagents/planner-experimenter.agent.md
new file mode 100644
index 000000000..7ed0b4203
--- /dev/null
+++ b/.github/agents/subagents/planner-experimenter.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Planning viewpoint - Experimenter. Use when: designing probes and tests to reduce uncertainty early."
+name: "Experimenter (Planner)"
+argument-hint: "Propose low-cost experiments and tests that de-risk the plan before full implementation."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Experimenter (Planner)
+
+Focus on uncertainty reduction:
+
+1. Identify highest-uncertainty assumptions.
+2. Design fast probes and validation checks.
+3. Prioritize experiments by information gain.
+
+## What You Do Not Do
+
+-   Do not propose expensive experiments before low-cost probes.
+-   Do not treat unresolved uncertainty as acceptable by default.
+
diff --git a/.github/agents/subagents/planner-historian.agent.md b/.github/agents/subagents/planner-historian.agent.md
new file mode 100644
index 000000000..4f204732f
--- /dev/null
+++ b/.github/agents/subagents/planner-historian.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Planning viewpoint - Historian. Use when: applying prior patterns, incidents, and known repository conventions."
+name: "Historian (Planner)"
+argument-hint: "Bring in prior patterns and historical lessons relevant to planning decisions."
+tools: [read, search]
+user-invocable: false
+---
+
+# Historian (Planner)
+
+Focus on prior knowledge:
+
+1. Reuse successful patterns.
+2. Flag prior incidents that suggest caution.
+3. Align plan to established repository conventions.
+
+## What You Do Not Do
+
+-   Do not force precedent when current context materially differs.
+-   Do not cite historical patterns without relevance to current task.
+
diff --git a/.github/agents/subagents/planner-simplifier.agent.md b/.github/agents/subagents/planner-simplifier.agent.md
new file mode 100644
index 000000000..a0db62ac4
--- /dev/null
+++ b/.github/agents/subagents/planner-simplifier.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Planning viewpoint - Simplifier. Use when: reducing scope, complexity, and dependency load in the plan."
+name: "Simplifier (Planner)"
+argument-hint: "Minimize complexity while preserving required outcomes."
+tools: [read, search, todo]
+user-invocable: false
+---
+
+# Simplifier (Planner)
+
+Focus on reduction:
+
+1. Remove unnecessary steps.
+2. Prefer the smallest viable path.
+3. Reduce moving parts and coupling.
+
+## What You Do Not Do
+
+-   Do not remove safeguards needed for high-severity risks.
+-   Do not simplify by dropping required acceptance criteria.
+
diff --git a/.github/agents/subagents/planner-synthesizer.agent.md b/.github/agents/subagents/planner-synthesizer.agent.md
new file mode 100644
index 000000000..243f76317
--- /dev/null
+++ b/.github/agents/subagents/planner-synthesizer.agent.md
@@ -0,0 +1,38 @@
+---
+description: "Planner loop synthesizer. Use when: reconciling planning viewpoints into one executable plan artifact."
+name: "Planner Synthesizer"
+argument-hint: "Combine Strategist, Investigator, Experimenter, Adversary, Simplifier, and Historian into a final plan."
+tools: [read, search, todo]
+user-invocable: false
+---
+
+# Planner Synthesizer
+
+Turn multiple planning viewpoints into one actionable plan.
+
+## What You Do
+
+-   Reconcile conflicts across Strategist, Investigator, Experimenter, Adversary, Simplifier, and Historian.
+-   Keep the plan executable by default.
+-   Record why rejected ideas were excluded.
+
+## What You Do Not Do
+
+-   Do not write code.
+-   Do not ignore subagent feedback silently.
+-   Do not invent new requirements.
+
+## Conflict Resolution Principles
+
+1. Facts beat speculation.
+2. Critical risk mitigations beat simplification.
+3. Simpler path wins when correctness and risk are equal.
+4. Experiments resolve disputes on uncertain assumptions.
+5. Historical precedent informs decisions but does not override current evidence.
+
+## Required Output Schema
+
+1. Decision Summary.
+2. Evidence Used.
+3. Conflict Resolution Log.
+
diff --git a/.github/agents/subagents/review-synthesizer.agent.md b/.github/agents/subagents/review-synthesizer.agent.md
new file mode 100644
index 000000000..573e280cc
--- /dev/null
+++ b/.github/agents/subagents/review-synthesizer.agent.md
@@ -0,0 +1,44 @@
+---
+description: "Review loop synthesizer. Use when: combining architectural, advocacy, and skeptical reviews into a release decision."
+name: "Review Synthesizer"
+argument-hint: "Synthesize Architect, Advocate, and Skeptic feedback into a conservative go/no-go decision."
+tools: [read, search, execute, todo]
+user-invocable: false
+---
+
+# Review Synthesizer
+
+Produce one release decision:
+
+1. Go.
+2. Go with documented residual risks.
+3. No-go with targeted rework request.
+
+Rework escalation must be conservative and evidence-backed.
+
+## Conflict Resolution Principles
+
+1. Evidence beats confidence claims.
+2. High-severity correctness risk beats schedule pressure.
+3. Clear requirement misses beat architectural preference debates.
+4. If two options are equally safe, choose lower churn.
+
+## Required Output Schema
+
+1. Decision Summary.
+2. Evidence Used.
+3. Conflict Resolution Log.
+4. Risks and Mitigations.
+5. Rejected Options.
+6. Unresolved Conflicts.
+7. Next Actions.
+
+## Loop-Specific Required Content
+
+1. Findings by severity.
+2. Residual risks accepted.
+3. Rework request (only if all escalation gates pass):
+    - Severity threshold met.
+    - Reproducible evidence included.
+    - Targeted scope for rework defined.
+
diff --git a/.github/agents/subagents/saboteur.agent.md b/.github/agents/subagents/saboteur.agent.md
new file mode 100644
index 000000000..0079cbfbe
--- /dev/null
+++ b/.github/agents/subagents/saboteur.agent.md
@@ -0,0 +1,37 @@
+---
+description: "Tester viewpoint - Saboteur. Use when: designing tests intended to break the implementation."
+name: "Saboteur (Tester)"
+argument-hint: "Design adversarial tests that stress failure modes and attempt to break the change."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Saboteur (Tester)
+
+Break-first testing:
+
+1. Craft failure-oriented inputs.
+2. Target boundary and invalid states.
+3. Expose brittle assumptions.
+
+## What You Do Not Do
+
+-   Do not focus on happy-path validation.
+-   Do not submit vague "might fail" claims without a concrete scenario.
+
+## Risk-Proportional Depth
+
+-   Low risk: 1-2 break attempts.
+-   Medium risk: 3-5 break attempts across boundaries and interactions.
+-   High risk: 5+ break attempts including concurrency or lifecycle stress.
+
+## Evidence Format
+
+For each break attempt provide:
+
+1. Attack scenario.
+2. Expected failure mode.
+3. Trace path.
+4. Severity.
+5. Confidence.
+
diff --git a/.github/agents/subagents/skeptic.agent.md b/.github/agents/subagents/skeptic.agent.md
new file mode 100644
index 000000000..8f65bf138
--- /dev/null
+++ b/.github/agents/subagents/skeptic.agent.md
@@ -0,0 +1,37 @@
+---
+description: "Review viewpoint - Skeptic. Use when: trying to break assumptions and finding hidden regressions."
+name: "Skeptic (Review)"
+argument-hint: "Challenge claims, attempt to break the solution, and surface hidden regressions."
+tools: [read, search, execute]
+user-invocable: false
+---
+
+# Skeptic (Review)
+
+Try to break it:
+
+1. Challenge assumptions and claims.
+2. Search for hidden regressions.
+3. Demand evidence for safety and correctness.
+
+## What You Do Not Do
+
+-   Do not relitigate already-closed low-risk choices.
+-   Do not block release without concrete evidence.
+
+## Risk-Proportional Depth
+
+-   Low risk: challenge core claim only.
+-   Medium risk: challenge core claim plus one adjacent behavior.
+-   High risk: challenge correctness, regression safety, and operational recovery.
+
+## Evidence Format
+
+For each skeptical finding provide:
+
+1. Claim challenged.
+2. Counter-scenario.
+3. Evidence path.
+4. Severity.
+5. Confidence.
+
diff --git a/.github/agents/subagents/strategist.agent.md b/.github/agents/subagents/strategist.agent.md
new file mode 100644
index 000000000..6c46f0bbe
--- /dev/null
+++ b/.github/agents/subagents/strategist.agent.md
@@ -0,0 +1,21 @@
+---
+description: "Planning viewpoint - Strategist. Use when: framing the end-to-end solution path and sequencing work."
+name: "Strategist (Planner)"
+argument-hint: "Provide an end-to-end execution strategy and sequencing for the task."
+tools: [read, search, todo]
+user-invocable: false
+---
+
+# Strategist (Planner)
+
+Focus on end-to-end framing:
+
+1. Desired outcome and constraints.
+2. Highest-leverage path.
+3. Step ordering and dependencies.
+
+## What You Do Not Do
+
+-   Do not perform deep code-level verification.
+-   Do not over-specify implementation details that belong to implementer roles.
+
diff --git a/.github/agents/subagents/tester-synthesizer.agent.md b/.github/agents/subagents/tester-synthesizer.agent.md
new file mode 100644
index 000000000..d9799086a
--- /dev/null
+++ b/.github/agents/subagents/tester-synthesizer.agent.md
@@ -0,0 +1,59 @@
+---
+description: "Tester loop synthesizer. Use when: combining adversarial tester signals into a coherent test strategy and final test outcomes."
+name: "Tester Synthesizer"
+argument-hint: "Synthesize Explorer, Inspector, and Saboteur findings into a concrete test plan and execution summary."
+tools: [read, edit, search, execute, todo]
+user-invocable: false
+---
+
+# Tester Loop Synthesizer
+
+## Role
+
+You synthesize evidence from adversarial tester subagents:
+
+-   Explorer: uncovers untested behaviors and missing coverage.
+-   Inspector: validates requirement compliance.
+-   Saboteur: designs failure-oriented and break tests.
+
+Your output is a coherent testing decision, not a dump of conflicting feedback.
+
+## Process
+
+1. Collect findings from Explorer, Inspector, and Saboteur.
+2. Resolve conflicts by preferring requirement correctness first, then robustness, then coverage depth.
+3. Produce a test strategy with:
+    - Must-add tests.
+    - Nice-to-add tests.
+    - Tests intentionally deferred (with rationale).
+4. Execute and summarize targeted test results.
+
+## Conflict Resolution Principles
+
+1. Requirement correctness beats coverage expansion.
+2. Reproducible failures beat speculative concerns.
+3. High-severity break tests beat nice-to-have coverage work.
+4. Deterministic tests beat flaky broad tests.
+
+## Required Output Schema
+
+1. Decision Summary.
+2. Evidence Used.
+3. Conflict Resolution Log.
+4. Risks and Mitigations.
+5. Rejected Options.
+6. Unresolved Conflicts.
+7. Next Actions.
+
+## Loop-Specific Required Content
+
+1. Requirement verification results.
+2. Coverage gaps found.
+3. Break tests that currently fail and why they matter.
+4. Completeness checklist:
+    - Primary regression.
+    - Inverse or sanity check.
+    - Boundary case.
+    - Interaction case.
+5. Prioritized recommended test edits or additions.
+
diff --git a/.github/instructions/python-best-practices.instructions.md b/.github/instructions/python-best-practices.instructions.md
new file mode 100644
index 000000000..77b77a9c5
--- /dev/null
+++ b/.github/instructions/python-best-practices.instructions.md
@@ -0,0 +1,98 @@
+---
+description: Best practices for developing Python code in this repository
+applyTo: '**/*.py'
+---
+
+# Python Best Practices
+
+## Section 1: Universal Rules
+
+Non-negotiable. Always follow these regardless of project tooling or configuration.
+
+### 1.1 Put All Tests in a `tests/` Directory
+
+Never scatter test files at the top level alongside source code. Place all tests in a dedicated `tests/` subdirectory. If using pytest, configure test path discovery in `pyproject.toml`.
+
+```
+# Correct
+my_project/
+  src/app.py
+  src/utils.py
+  tests/test_app.py
+  tests/test_utils.py
+```
+
+### 1.2 Use the Simplest Build Tool That Works
+
+For pure Python projects, prefer modern build backends like hatchling or pdm-backend. Do not default to setuptools unless the project already uses it.
+
+### 1.3 Never Write Dependencies in Multiple Places
+
+Define direct dependencies in one place only (`pyproject.toml`). Do not duplicate them across `requirements.txt`, `pyproject.toml`, and `setup.py`.
+
+### 1.4 Dev Dependencies Go in `[dependency-groups]`
+
+Development dependencies (pytest, ruff, mypy) belong in `[dependency-groups] dev`, not `[project.optional-dependencies]`.
+
+### 1.5 Use Leading Underscores for Non-Public APIs
+
+Add leading underscores to modules, classes, functions, and methods that are not part of the public API.
+
+### 1.6 Imports Belong at the Top of the File
+
+Place all imports at the top of the file. Inline imports should only be used for lazy loading or circular import resolution.
+
+### 1.7 Follow PEP 8 Naming Conventions
+
+- `snake_case` for functions and variables
+- `PascalCase` for classes
+- `UPPER_SNAKE_CASE` for constants
+- `_leading_underscore` for private/internal names
+
+### 1.8 Write Idiomatic Python for the Target Version
+
+Use features available in the project's target Python version. Use `match`/`case`, type union syntax (`X | Y`), `pathlib`, and built-in generics where supported.
+
+### 1.9 Avoid Deep Nesting — Use Early Returns
+
+Avoid nesting code deeper than 3 levels. Use guard clauses, early returns, `continue` in loops, and extracted helper functions to flatten logic.
+
+### 1.10 Default to Fail-Closed Logic
+
+For authorization and security checks, structure code to fail-closed (deny by default).
+
+### 1.11 Prefer Built-ins and Comprehensions Over Helper Methods
+
+Use `any()`, `all()`, `sum()`, `min()`, `max()` and other built-ins. Leverage comprehensions and generators.
+
+### 1.12 Match the Project's Existing Test Framework
+
+Default to pytest unless preexisting code uses unittest. Respect existing patterns.
+
+### 1.13 Don't Over-Mock in Tests
+
+Mock external dependencies (APIs, databases) but test actual business logic with real objects when possible.
+
+### 1.14 Don't Over-Document — Explain Why, Not What
+
+Comments should explain why, not what. Code should be self-documenting through clear naming.
+
+### 1.15 Write Library-Quality Code, Not Scripts
+
+Structure code as a library or reusable software product. Use proper classes, modules, error handling, and separation of concerns.
+
+## Section 2: Environment-Aware Guidance
+
+These rules adapt based on detected project conventions. Framework-specific skills extend this section.
+
+### 2.1 Formatter and Linter
+
+If a project configuration is detected (e.g. `ruff.toml`, `pyproject.toml [tool.ruff]`, `.flake8`), follow the project's formatter/linter. If none is detected, prefer Ruff for both formatting and linting.
+
+### 2.2 Source Layout
+
+Respect the detected source layout (`src/` layout vs flat package). If creating a new project, prefer the `src/` layout.
+
+### 2.3 Test Framework
+
+Detect and follow the existing test framework. If no existing framework is detected, default to pytest.
diff --git a/TROUBLESHOOTING.md b/TROUBLESHOOTING.md
index a8dbc6a26..0525536ad 100644
--- a/TROUBLESHOOTING.md
+++ b/TROUBLESHOOTING.md
@@ -23,6 +23,41 @@ If you want to debug library files, you have to disable `justMyCode` in `launch.
 },
 ```
 
+### Debugger breaks on SystemExit
+By default, the debugger treats `SystemExit` with a non-zero exit code as an uncaught exception and breaks on it. If you use `sys.exit()` intentionally (e.g. in CLI tools, test runners like pytest, or frameworks like Django/Flask), this can be unwanted.
+
+You can control exactly which `SystemExit` codes the debugger breaks on using the `breakOnSystemExit` setting in `launch.json`. It accepts an array of exit codes and/or ranges:
+
+```js
+// Never break on any SystemExit:
+    {
+        "breakOnSystemExit": []
+    }
+
+// Only break on specific exit codes:
+{
+    "breakOnSystemExit": [1, 2]
+}
+
+// Break on exit codes using ranges (inclusive):
+{
+    "breakOnSystemExit": [{"from": 1, "to": 255}]
+}
+
+// Mix specific codes and ranges:
+{
+    "breakOnSystemExit": [0, {"from": 3, "to": 100}]
+}
+```
+
+When `breakOnSystemExit` is not specified, the default behavior applies:
+- `SystemExit(0)` and `SystemExit(None)` are ignored (successful exit).
+- All other non-zero exit codes cause a break.
+- When **`django`** or **`flask`** is `true`, exit code `3` is also ignored (used for reload signaling).
+- When **`breakOnSystemExitZero`** is `true`, the debugger also breaks on `SystemExit(0)` and `SystemExit(None)`.
+
+When `breakOnSystemExit` is explicitly set, it overrides all of the above — only the listed codes and ranges will cause breaks.
+
 ## Filing an issue
 
 When filing an issue, make sure you do the following:
diff --git a/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_api.py b/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_api.py
index c85ad0f09..5899587e8 100644
--- a/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_api.py
+++ b/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_api.py
@@ -994,6 +994,9 @@ def stop_on_entry(self):
     def set_ignore_system_exit_codes(self, py_db, ignore_system_exit_codes):
         py_db.set_ignore_system_exit_codes(ignore_system_exit_codes)
 
+    def set_break_on_system_exit(self, py_db, codes, ranges):
+        py_db.set_break_on_system_exit(codes, ranges)
+
     SourceMappingEntry = pydevd_source_mapping.SourceMappingEntry
 
     def set_source_mapping(self, py_db, source_filename, mapping):
diff --git a/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_process_net_command_json.py b/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_process_net_command_json.py
index 1fe207c21..0c483af49 100644
--- a/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_process_net_command_json.py
+++ b/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_process_net_command_json.py
@@ -119,6 +119,51 @@ def _convert_rules_to_exclude_filters(rules, on_error):
     return exclude_filters
 
 
+def _parse_break_on_system_exit(args):
+    """Parse the ``breakOnSystemExit`` launch/attach argument.
+
+    :returns:
+        ``(codes_set, ranges_list)`` when the setting is present and valid,
+        or ``None`` when it is absent or completely invalid.
+    """
+    break_on_system_exit = args.get("breakOnSystemExit", None)
+    if break_on_system_exit is None:
+        return None
+
+    if not isinstance(break_on_system_exit, (list, tuple)):
+        pydev_log.info("Expected breakOnSystemExit to be a list. Received: %s" % (break_on_system_exit,))
+        return None
+
+    codes = set()
+    ranges = []
+    for item in break_on_system_exit:
+        if item is None:
+            codes.add(None)
+        elif isinstance(item, int):
+            codes.add(item)
+        elif isinstance(item, dict):
+            range_from = item.get("from", 0)
+            range_to = item.get("to", 0)
+            if not isinstance(range_from, int) or not isinstance(range_to, int):
+                pydev_log.info(
+                    "Expected 'from' and 'to' in breakOnSystemExit range to be integers. "
+                    "Received: from=%s, to=%s" % (range_from, range_to)
+                )
+                continue
+            if range_from > range_to:
+                pydev_log.info(
+                    "breakOnSystemExit range has 'from' > 'to' (matches nothing): "
+                    "from=%s, to=%s" % (range_from, range_to)
+                )
+            ranges.append((range_from, range_to))
+        else:
+            pydev_log.info(
+                "Unexpected item type in breakOnSystemExit (expected int, None, or dict): %s" % (item,)
+            )
+
+    return (codes, ranges)
+
+
 class IDMap(object):
     def __init__(self):
         self._value_to_key = {}
@@ -433,7 +478,11 @@ def get_variable_presentation(setting, default):
 
         self.api.set_show_return_values(py_db, self._options.show_return_value)
 
-        if not self._options.break_system_exit_zero:
+        parsed = _parse_break_on_system_exit(args)
+        if parsed is not None:
+            codes, ranges = parsed
+            self.api.set_break_on_system_exit(py_db, codes, ranges)
+        elif not self._options.break_system_exit_zero:
             ignore_system_exit_codes = [0, None]
             if self._options.django_debug or self._options.flask_debug:
                 ignore_system_exit_codes += [3]
diff --git a/src/debugpy/_vendored/pydevd/pydevd.py b/src/debugpy/_vendored/pydevd/pydevd.py
index db0336448..739693e9b 100644
--- a/src/debugpy/_vendored/pydevd/pydevd.py
+++ b/src/debugpy/_vendored/pydevd/pydevd.py
@@ -774,6 +774,7 @@ def new_trace_dispatch(frame, event, arg):
         self._exclude_by_filter_cache = {}
         self._apply_filter_cache = {}
         self._ignore_system_exit_codes = set()
+        self._break_on_system_exit = None  # None = default behavior, tuple = (codes_set, ranges_list)
 
         # DAP related
         self._dap_messages_listeners = []
@@ -926,11 +927,45 @@ def set_ignore_system_exit_codes(self, ignore_system_exit_codes):
         assert isinstance(ignore_system_exit_codes, (list, tuple, set))
         self._ignore_system_exit_codes = set(ignore_system_exit_codes)
 
+    def set_break_on_system_exit(self, codes, ranges):
+        """Set explicit list of SystemExit codes to break on.
+
+        :param set codes:
+            Set of specific exit codes (ints, None) to break on.
+        :param list ranges:
+            List of (from_code, to_code) tuples (inclusive) to break on.
+        """
+        self._break_on_system_exit = (codes, ranges)
+        self._ignore_system_exit_codes = set()  # Clear legacy state to prevent conflicts
+
     def ignore_system_exit_code(self, system_exit_exc):
-        if hasattr(system_exit_exc, "code"):
-            return system_exit_exc.code in self._ignore_system_exit_codes
-        else:
-            return system_exit_exc in self._ignore_system_exit_codes
+        """Determine whether to ignore (not break on) a SystemExit exception.
+
+        Returns True to ignore (skip the break), False to break.
+
+        When ``_break_on_system_exit`` is set, the semantics are inverted:
+        the configuration specifies which codes TO BREAK ON, and this method
+        returns False (don't ignore) if the code matches.  Non-int, non-None
+        codes (e.g. strings passed to ``sys.exit("error")``) are treated as
+        "always break" to avoid silently suppressing unexpected exits.
+        """
+        code = system_exit_exc.code if hasattr(system_exit_exc, "code") else system_exit_exc
+
+        if self._break_on_system_exit is not None:
+            codes_set, ranges_list = self._break_on_system_exit
+            if code in codes_set:
+                return False
+            if isinstance(code, int):
+                for range_from, range_to in ranges_list:
+                    if range_from <= code <= range_to:
+                        return False
+                return True
+            if code is None:
+                return True
+            # Non-int, non-None codes (e.g. strings): always break.
+            return False
+
+        return code in self._ignore_system_exit_codes
 
     def block_until_configuration_done(self, cancel=None):
         if cancel is None:
diff --git a/tests/debug/config.py b/tests/debug/config.py
index 90115ef8e..eeb2e910b 100644
--- a/tests/debug/config.py
+++ b/tests/debug/config.py
@@ -27,6 +27,7 @@ class DebugConfig(MutableMapping):
     PROPERTIES = {
         # Common
         "breakOnSystemExitZero": False,
+        "breakOnSystemExit": None,
         "debugOptions": [],
         "django": False,
         "jinja": False,
diff --git a/tests/debugpy/test_exception.py b/tests/debugpy/test_exception.py
index bf21c9dd7..444fc0a42 100644
--- a/tests/debugpy/test_exception.py
+++ b/tests/debugpy/test_exception.py
@@ -333,6 +333,139 @@ def code_to_debug():
             session.request_continue()
 
 
+@pytest.mark.parametrize("target", targets.all_named)
+@pytest.mark.parametrize("run", runners.all)
+@pytest.mark.parametrize("exit_code", [0, 1, 3])
+def test_break_on_system_exit_empty(pyfile, target, run, exit_code):
+    @pyfile
+    def code_to_debug():
+        import debuggee
+        import sys
+
+        debuggee.setup()
+        exit_code = eval(sys.argv[1])
+        print("sys.exit(%r)" % (exit_code,))
+        sys.exit(exit_code)
+
+    with debug.Session() as session:
+        session.expected_exit_code = some.int
+        session.config["breakOnSystemExit"] = []
+
+        with run(session, target(code_to_debug, args=[repr(exit_code)])):
+            session.request(
+                "setExceptionBreakpoints", {"filters": ["raised", "uncaught"]}
+            )
+
+        # With breakOnSystemExit=[], no SystemExit should cause a break,
+        # regardless of exit code. The session should end without stopping.
+
+
+@pytest.mark.parametrize("target", targets.all_named)
+@pytest.mark.parametrize("run", runners.all)
+def test_break_on_system_exit_specific_codes(pyfile, target, run):
+    @pyfile
+    def code_to_debug():
+        import debuggee
+        import sys
+
+        debuggee.setup()
+        exit_code = eval(sys.argv[1])
+        print("sys.exit(%r)" % (exit_code,))
+        sys.exit(exit_code)
+
+    # Exit code 1 is in the break list, so should break.
+    with debug.Session() as session:
+        session.expected_exit_code = some.int
+        session.config["breakOnSystemExit"] = [1]
+
+        with run(session, target(code_to_debug, args=["1"])):
+            session.request(
+                "setExceptionBreakpoints", {"filters": ["uncaught"]}
+            )
+
+        session.wait_for_stop("exception")
+        session.request_continue()
+
+
+@pytest.mark.parametrize("target", targets.all_named)
+@pytest.mark.parametrize("run", runners.all)
+def test_break_on_system_exit_skips_unlisted_codes(pyfile, target, run):
+    @pyfile
+    def code_to_debug():
+        import debuggee
+        import sys
+
+        debuggee.setup()
+        exit_code = eval(sys.argv[1])
+        print("sys.exit(%r)" % (exit_code,))
+        sys.exit(exit_code)
+
+    # Exit code 2 is NOT in the break list, so should not break.
+    with debug.Session() as session:
+        session.expected_exit_code = some.int
+        session.config["breakOnSystemExit"] = [1]
+
+        with run(session, target(code_to_debug, args=["2"])):
+            session.request(
+                "setExceptionBreakpoints", {"filters": ["uncaught"]}
+            )
+
+        # Should not break - exit code 2 is not in the break list.
+
+
+@pytest.mark.parametrize("target", targets.all_named)
+@pytest.mark.parametrize("run", runners.all)
+def test_break_on_system_exit_range(pyfile, target, run):
+    @pyfile
+    def code_to_debug():
+        import debuggee
+        import sys
+
+        debuggee.setup()
+        exit_code = eval(sys.argv[1])
+        print("sys.exit(%r)" % (exit_code,))
+        sys.exit(exit_code)
+
+    # Exit code 5 is within the range {"from": 3, "to": 10}, so should break.
+    with debug.Session() as session:
+        session.expected_exit_code = some.int
+        session.config["breakOnSystemExit"] = [{"from": 3, "to": 10}]
+
+        with run(session, target(code_to_debug, args=["5"])):
+            session.request(
+                "setExceptionBreakpoints", {"filters": ["uncaught"]}
+            )
+
+        session.wait_for_stop("exception")
+        session.request_continue()
+
+
+@pytest.mark.parametrize("target", targets.all_named)
+@pytest.mark.parametrize("run", runners.all)
+def test_break_on_system_exit_range_skips_outside(pyfile, target, run):
+    @pyfile
+    def code_to_debug():
+        import debuggee
+        import sys
+
+        debuggee.setup()
+        exit_code = eval(sys.argv[1])
+        print("sys.exit(%r)" % (exit_code,))
+        sys.exit(exit_code)
+
+    # Exit code 2 is outside the range {"from": 3, "to": 10}, so should not break.
+    with debug.Session() as session:
+        session.expected_exit_code = some.int
+        session.config["breakOnSystemExit"] = [{"from": 3, "to": 10}]
+
+        with run(session, target(code_to_debug, args=["2"])):
+            session.request(
+                "setExceptionBreakpoints", {"filters": ["uncaught"]}
+            )
+
+        # Should not break - exit code 2 is outside the range.
+
+
 @pytest.mark.parametrize("max_frames", ["default", "all", 10])
 def test_exception_stack(pyfile, target, run, max_frames):
     @pyfile