Skip to content

Changelog

All notable changes to mklang are documented here. The format follows Keep a Changelog.

Two version lines are tracked separately:

  • Spec version — the language, declared per-file via the mklang: field (currently "0.3"; "0.2" documents remain valid).
  • Package version — the reference interpreter / tooling, SemVer in pyproject.toml (currently 0.11.0).

[0.11.0] — 2026-07-18

Global vs local configuration separation (ADR 0023) — language stays 0.3.

Added

  • mklang doctor — diagnose the resolved setup: winning config file and layer (project / user / system / bundled), schema validation of the resolved config (stale keys surface as warnings), which .env files loaded, per-provider key status (active-provider gaps are errors, local exempt), tool backends (search/kb/mail), machine roots with counts, and the state paths. Exit 1 when the active provider cannot run.
  • mklang init --user now also copies runtime.schema.json next to the user runtime.yaml (parity with project mode; editor validation works in both).
  • run --hitl without --checkpoint suspends into $XDG_STATE_HOME/mklang/checkpoints/ instead of erroring; the suspension message prints the generated path.

Changed

  • .env now layers per key: real environment > project .env > user ~/.config/mklang/.env. Previously any project .env hid the user file entirely, even for keys it did not define.
  • mklang-mcp resolves its config through the same chain as the CLI (project → user → /etc → bundled) instead of pinning the checkout-relative bundled example — MCP clients no longer need an explicit --config.
  • The console workspace defaults to ./machines only when it exists, falling back to the XDG user machines dir seeded by mklang init --user.

Removed

  • The dead run: block (max_repair_per_gate, trace) from the example config and its schema: the runtime never read it — repair budgets live in each gate (repair: N, SPEC §7) and the trace is always part of the run result. mklang doctor flags it as a stale key in existing configs.
  • The legacy ~/.mklang/console/sessions read fallback: sessions live only under the XDG state root (ADR 0021's migration window is over).

[0.10.0] — 2026-07-18

First-run experience (language stays 0.3).

Added

  • Getting started guide — one linear install → init → key → console path, first in the docs nav.
  • mklang --version, and a getting-started nudge (exit 0) on bare mklang instead of a usage error.
  • mklang init seeds machines/ with a commented hello.mk sample and its hello.test.yaml scenario script (keyless first run via mklang test).
  • Upfront provider key gate: runs, the console, and lint --llm fail fast with the exact .env variable to set instead of dying inside the provider SDK (local stays exempt).
  • Shell completions via argcomplete ([completions] extra).
  • ADR 0021 phase 3 packaging: scripts/install.sh (pipx + mklang init --user, with --uninstall) and an Arch Linux recipe in packaging/arch/; the optional MCP user service is deferred (stdio-only server).

Changed

  • README install/quickstart restructured: pipx path first, checkout/uv workflow kept as the from-checkout section.
  • Lean sdist: exclude media assets, site/, demos/, dist/, and .github/ from the source distribution (the AUR recipe builds from it).

[0.9.3] — 2026-07-17

Documentation-alignment patch (language stays 0.3).

Fixed

  • Make the best-practices guide the documentation SSOT for current XDG host paths and console lifecycle behavior.
  • Align the console session path with ADR 0021 while retaining the legacy path as a documented read fallback.
  • Bring the README live-matrix status and roadmap history up to date through the 0.9.2 release, and mark ADR 0015's original path as superseded.

[0.9.2] — 2026-07-17

Console shutdown patch (language stays 0.3).

Fixed

  • Shut down the console cleanly when Ctrl+C is pressed during an active run: request cooperative cancellation, release pending human prompts, close the provider client, and wait for the backing thread before returning to the shell.
  • Prevent late UI callbacks and session writes after console shutdown starts.

[0.9.1] — 2026-07-17

Release-pipeline patch (language stays 0.3).

Fixed

  • Keep fatal CLI diagnostics on one stable line when stdout/stderr is not a TTY.
  • Skip the console-session CLI test when the optional Textual extra is absent.

[0.9.0] — 2026-07-17

Feature release (language stays 0.3). Every local surface now works outside a repository checkout, preserves automation-safe output, and presents a responsive operational workspace in the terminal.

Added

  • Responsive console and CLI presentation (ADR 0022). Rich human output with stable piped JSON, shared diagnostics, responsive inspector/activity layout, slash-command quoting/suggestions, operational status, cooperative stop, and additive run-finished events.
  • ADR 0021 phases 1–2. XDG host paths, bundled config fallback, idempotent mklang init, legacy console-session reads, and system/user/project machine discovery with source labels.

Fixed

  • Connection errors now retry. Provider _create loops treated only HTTP TRANSIENT_STATUS as retryable; SDK connection failures carry no status_code, so a network blip halted the run with provider-error on the first try. is_connection_error (matched by class name — the SDKs are lazy-imported) classifies APIConnectionError / APITimeoutError as transient with the same exponential backoff, for both the Anthropic and OpenAI-compat adapters.

[0.8.2] — 2026-07-17

Package patch (language stays 0.3). Documentation growth (best practices §12–§13) plus a console glyph fix and a CI test guard.

Added

  • Best practices §12–§13 — observability (trace vs live events vs process logging) and filesystem taxonomy (host paths / workspace .mk / data tools / no bash in core). Cross-links from console security and patterns.

Fixed

  • Console activity tree double expand icon. Run rows no longer prefix ▶ in the label — Textual Tree already draws the ▶/▼ toggle.
  • CI: console render tests skip without rich. test_console_render.py now uses pytest.importorskip("rich") like the other console tests, so the no-console-extra CI matrix collects cleanly.

[0.8.1] — 2026-07-17

Package patch (language stays 0.3). Console rendering safety, host wall-clock, and produce system-prompt assembly — surface/host polish only.

Added

  • Host clock convention context.now. When a machine declares top-level now and it is still empty after inputs, CLI / MCP / console fill a local ISO datetime with offset (same opt-in pattern as today). Console agent.mk declares now and is instructed to REPLY wall-clock questions from the host values (no AUTHOR for the clock alone).
  • Produce system prompt assembly (llm/prompts.py): sectioned system message from structure + execution; documented as Best practices §3 (system vs user). Console agent.mk puts sticky policy in execution and turn data in prompt.

Changed

  • Console conversation rendering (chrome vs content). Agent replies render as CommonMark in the log; user/HITL text and slash observations stay plain or fenced (json / yaml). Activity tree turn titles, machine names, and output previews use plain styled Text (no Rich-markup injection). Helpers live in console/render.py; log uses markup=False.
  • Docs: SPEC §4–§6 non-normative notes (produce system/user assembly, host clocks); Best practices §3; authoring faces table; console brain prompt assembly; README faces/status; ADR 0016 now checklist.

[0.8.0] — 2026-07-17

Package feature release (language stays 0.3). Host tools gain a uniform stub architecture; console anti-cutoff observations stay honest; time-sensitive machines get a host today convention and richer search.

Fixed

  • Console run_machine observation honesty (anti-cutoff chain). Produce truncation (ADR 0018) is propagated as truncated / finish_reason plus a compact trace summary; long results are clipped with an explicit …[truncated] marker and result_truncated — no more silent 2k cuts that invited the brain to invent the missing tail.

Added

  • Host convention context.today. When a machine declares top-level today and it is still empty after inputs, CLI / MCP / console fill the host ISO date (YYYY-MM-DD). Never invents undeclared keys.
  • Search recency fields (ADR 0016 addendum): optional tool inputs days / topic; optional published_date on results (Tavily when provided).
  • Research / news patterns and agent.mk instruct grounding in notes/today and forbid filling gaps with pre-training knowledge; console docs document the observation shape.
  • Best practices guide (docs/best-practices.md) — layer discipline, authoring checklist, recommended tool contracts, web/time/cutoff rules, anti-patterns, and what must stay host-side vs candidate language 0.4.
  • Host tool stub architecture (ADR 0020): shared JSON envelope (tool / stub / error) for I/O tools; search_kb and send_reply use structured observations; default send_reply has sent: false (no fake delivery); fake backends via MKLANG_KB_BACKEND / MKLANG_MAIL_BACKEND and configure_kb / configure_mail; modules tool_obs, kb, mail.
  • news_search scenario tests (examples/news_search.test.yaml) — happy path and search-unbound → no_search.
  • OpenAI-compatible produce defaults max_tokens=4096 when tier params omit it (parity with Anthropic; reduces silent length stops; still overridable / droppable per provider).

Changed

  • Breaking (host observation shape only): builtin search_kb / send_reply no longer return free-text [kb stub]… / [sent]… strings — they return ADR 0020 JSON. Scripted scenario tools are unaffected. search adds tool + stub fields (additive).

[0.7.0] — 2026-07-17

Package feature release (language stays 0.3). Console becomes a full operational front door; host tools and runtime budgets close the agent loop.

Added

  • Console M1–M3 (ADR 0015 Accepted). Agent-first Textual TUI (mklang[console]) whose brain is the bundled, user-swappable agent.mk: authoring loop (write → validate → repair), persistent sessions (--continue / --session), budget-exhaustion park//resume, live activity tree, F2 inspector, slash commands. Docs: docs/console.md.
  • Live engine events on the MCP transport (ADR 0019): run/resume stream on_event as mklang.event logging notifications.
  • Web search tool (ADR 0016 Accepted): structured JSON search observations; offline stub by default; opt-in fake/tavily backends; examples/research_web.mk + scenario tests.
  • Output anti-cutoff (ADR 0018 Accepted): Produced.truncated / finish_reason; trace + events; report|halt on CLI (--on-truncate), MCP, console, scripttest. Truncated parse: list → parse-list-truncated.
  • Context management Layer 0–1 (ADR 0017 Accepted): judge CONTEXT head+tail marker; produce-prompt per-value cap; console history_for_brain; compress pattern examples/research_compress.mk.
  • LLM-assisted lint (mklang lint --llm, ADR 0010 Accepted): advisory only.

[0.6.0] — 2026-07-17

The language moves to 0.3 (additive; every 0.2 document remains valid) and the agent-facing surfaces land: MCP host, machine stdlib, discovery, authoring guide.

Added — language 0.3 (ADR 0014)

  • parse: list — a generative state can deposit a parsed JSON array (markdown fences tolerated) instead of text; unparseable output halts cleanly with state-error: parse-list. This makes Plan-and-Execute a pure machine.
  • Raw whole-template input: resolution — an input: value that is exactly one {{path}} placeholder passes the raw context value (lists included) across call:/tool: boundaries; mixed templates render as before.
  • Conformance cases parse-list, parse-list-invalid, raw-input-passthrough; the JSON Schema (both copies) gains the parse enum; check warns when a 0.2 document uses the new face.

Added — surfaces

  • MCP server surface (ADR 0011, now Accepted). Optional stdio MCP host — extra mklang[mcp], console script mklang-mcp — exposing exactly two tools: run (machine as inline .mk source or filesystem path, inputs merged into the context, optional cost_budget/hitl) and resume (opaque single-use checkpoint handle, HITL reply injection, new budget). Results return the same {status, error, result, usage, trace, at?} shape the CLI prints. Suspended runs hold their frames in a process-scoped in-memory session store; nothing is written to disk. Core install is unaffected (mcp is not a core dependency).
  • Public host seam mklang.host — prepare_path / prepare_source (inline source loading is new) / build_output / set_path, with structured PrepareError instead of printed diagnostics. The CLI now wraps this seam, so CLI and MCP semantics cannot drift.
  • Agent authoring guide (docs/authoring.md) — a compact recipe for writing a correct .mk with the check/lint loop, distilled from SPEC with the real validator messages.
  • Machine stdlib (ADR 0012). Eight general-purpose architecture machines bundled with the package — std_cot, std_self_consistency, std_refine, std_tot, std_debate, std_map_reduce, std_cascade, std_plan_execute — uniform contract (task in, answer out), each with scripted scenario tests. Present in every host registry with user-always-wins precedence (stdlib ← mklang.machines entry-point plugins ← siblings ← target, shadowing warned); runnable by name from CLI and MCP (mklang run std_cot --set task="…"); inline MCP sources can call: std_*. Run-by-name checkpoints record a null machine hash and resume cleanly. Catalog in docs/stdlib.md.
  • Discovery, check, durable resume (ADR 0013). MCP tools list_machines / describe_machine (what may be commissioned, with full contracts), check (schema + semantics + lint as structured output, no provider needed), and checkpoint_path on run/resume for cross-process durable suspensions — resume accepts an in-memory handle or a checkpoint file, including files from mklang run --checkpoint; inline sources persist via a new optional machine_source envelope key. CLI gains the symmetric mklang machines subcommand (JSON; --dir adds project machines).

Changed

  • CI runs the unit suite with the mcp extra (the MCP tests no longer skip silently) and checks/lints the bundled stdlib alongside the examples.
  • Unknown run-by-name targets fail with the list of bundled machine names instead of a raw errno message.
  • # noqa annotations removed across the codebase (the suppressed rule was never enabled); explanatory comments remain.

[0.5.4] — 2026-07-16

Release-readiness pass. The language stays 0.2 and runtime semantics are unchanged; this release makes the existing interpreter reproducibly distributable.

Added

  • Trusted Publishing release workflow. A published GitHub Release now gates publication on the full offline suite, strict docs, artifact validation, a clean-wheel installation smoke, and the live provider matrix. The publish job consumes the already-tested artifacts and uses short-lived PyPI OIDC credentials.
  • Enforceable live-matrix reporting. scripts/gate_divergence.py can require named providers, enforce a minimum agreement rate, write a summary artifact, and distinguishes a missing-key skip from a provider/runtime failure.
  • Release provenance tests. CI pins package metadata and mklang.__version__ to the same value and tests the required-provider gate offline.

Changed

  • DeepSeek and OpenAI are the blocking release providers (three divergence runs, agreement 1.0). Anthropic, Google, OpenRouter, xAI, and Mistral are attempted when credentials are configured and remain informational.

[0.5.3] — 2026-07-16

Third remediation pass (Follow-up 003): closes the residue Remediation 002 delivered without declaring. The language stays 0.2; no .mk needs changes.

Added

  • mklang test — deterministic machine testing without API keys (R3-1). A new subcommand runs a machine against a script of named scenarios with a scripted LLM (produce texts + judge picks) and scripted tools/hooks — fully deterministic, no provider or key. Per-scenario PASS/FAIL with a minimal diff (first mismatched key, expected vs actual); exit 0 iff all pass. The scripted LLM, hooks:/tools: bindings, and expectation matcher now live once in src/mklang/scripttest.py, shared with the conformance runner (all 21 cases green through it, unchanged). Ships examples/triage.test.yaml (happy path + KB-empty escalation). Docs: README "Test your machine without API keys", docs/patterns.md, conformance/README.md cross-reference. CI runs uv run mklang test examples/triage.mk --script examples/triage.test.yaml in the unit-test job (no API keys); the same scenarios are also covered by tests/test_scripttest.py in the normal pytest run.
  • Static budget-feasibility check (R3-2). mklang check/lint now BFS the shortest path (in states) from entry to a gate to: END. budget below it is a guaranteed budget-exhausted halt, reported as error budget-infeasible; budget < shortest + 2 warns (no headroom for a single repair). Fan-out states count as 1 (branch counts are data-dependent), so the check is a lower bound — the message says so. SPEC §7 documents it next to the charging rule. Host pre-validation only; run semantics unchanged.
  • Dotted second-segment lint on inline context maps (R3-3, completes F7). When a {{root.key}} root resolves to an inline dict literal in context: (ticket: {body: …}), the second segment is now validated against the map's keys, so {{ticket.bod}} is flagged. Skipped for state outputs and runtime roots (human/item/index) whose shape is unknowable; deeper than segment 2 stays out of scope.
  • Schema-copy identity test (R3-4). One test asserts schema/mklang.schema.json and the packaged copy src/mklang/data/mklang.schema.json are byte-identical, with a failure message naming the sync direction (repo schema/ is the source).
  • ADR 0010 — LLM-assisted lint (R3-5, Proposed, design only). An opt-in mklang lint --llm that would generate synthetic outputs and measure gate-selection stability/overlap (reusing gate_divergence.py) to catch ambiguous prose when conditions. Documents cost model, determinism caveats, relation to the conformance suite, and why it is out of 0.5.x. No code.

[0.5.2] — 2026-07-16

Second remediation pass. The language stays 0.2; no .mk needs changes.

Changed (observable behavior)

  • Default judge model now follows each state's tier (F1). Previously every gate — including the highest-stakes gates on reasoning states (refund thresholds, legal matters, human escalation) — was judged by the cheapest (fast) model, silently deviating from SPEC §2.1. Gate judging now uses the state's own effective tier by default. This changes which model judges your gates. To restore the previous single-model behavior, set the provider judge: key in the runtime config — it is now an explicit, opt-in global override, no longer the default (it ships commented out in config/runtime.example.yaml). The chosen judge model is recorded in the trace as judge_model on every gate_via: llm step. Gate-divergence numbers collected before this change are not comparable with those after; re-run scripts/gate_divergence.py (now with a --judge-tier flag) to refresh them.

Fixed

  • Strict judge-reply parsing (F2). The bare-number fallback no longer grabs the first digit anywhere in the reply (a verbose judge's "Condition 1 fails…" misread as choice 1). Parse order is now: strict JSON, then a whole-reply bare number, then the last number in the reply (models conclude with the answer). The last two are traced as judge_parse (anomaly-adjacent, not a fallback). The judge system prompt now forbids extra numbers; SPEC §5 constrains conformant judges to terse instruct-style replies.
  • sample branch diversity (F3). Each sample: N branch now sees its own {{index}} (0-based), so a prompt can say "you are branch {{index}}, take a different approach" (Tree-of-Thought, debate) instead of relying on temperature alone. {{index}} is now available in both fan-out forms; {{item}} remains over-only.

Added

  • unresolved-interpolation lint rule (F7). mklang lint flags any {{path}} whose first segment no context: key / state output: / (inside a fan-out) item/index provides — the silent-typo bug ({{kb_answr}} → empty string). item/index referenced outside a fan-out state are flagged too. First-segment only (dotted tails can't be checked statically); warning by default, error under --strict.
  • --strict rejects unsupported mklang: versions (F6). An unknown language version stays a warning by default but becomes a hard error (version-unsupported) under mklang check --strict / lint --strict / the new run --strict.
  • 0600 checkpoints (F5). Checkpoint files (full blackboard as plaintext JSON) are written owner-only. SPEC §11 now lists checkpoints as an asset and documents the plaintext-at-rest surface (host-side mitigation; encryption is a v0.2 non-goal). The --checkpoint help notes the plaintext content.
  • Conformance coverage for hook precedence and tool states (F8). The case format gains scripted hooks: (boolean sequences) and tools: (list or {input-substring: output} map) bindings, plus expect.error_prefix. New cases: hook-before-prose, hook-false-falls-through, tool-state-output-deposit, tool-unknown-halts, fanout-sample-index (F3), budget-fanout-charging (F4). Suite: 15 → 21 cases.
  • SPEC §7 now states the fan-out step-charging rule (max(1, len(branches))) explicitly, with the map-reduce budget-sizing implication and a worked example; docs/patterns.md and ROADMAP note the possible v0.3 budget/branch_budget split.

Deferred from Remediation 002, delivered in 0.5.3: author-facing scripted testing (mklang test), budget-feasibility check, dotted-segment lint, schema-identity test, ADR 0010.

[0.5.1] — 2026-07-16

Fixed

  • Judge silent clamp — out-of-range or 0-based {"choice": k} replies are no longer clamped to a valid gate. parse_choice returns None for OOR; adapters raise JudgeUnparseable; the engine does not re-clamp. Soft-fallback to otherwise (or hard-halt judge-unparseable) is traced via judge_fallback / judge_raw — never a mute misroute with only gate_via: llm.
  • Showcase honesty (triage.mk) — search_kb and send_reply are real tool: states (host stubs); generative states no longer claim tool use or “confirm the send.” Same honesty pass on research.mk (no fake web_search).
  • README — dropped “no host code required”; documented that tools/hooks are host-supplied; centered conformance + portable spec as the differentiator.

Added

  • Builtins / entry points: search_kb, send_reply (deterministic stubs).
  • SPEC §5 — normative 1-based judge protocol; OOR = anomaly; documented JUDGE_CONTEXT_CHARS (4000) truncation.
  • SPEC §11 Threat model (v0.2) — injection surface, partial mitigations, explicit non-goals (declare rather than deny).
  • Reference produce temperature defaults documented (non-normative).
  • Gate-divergence experiment — scripts/gate_divergence.py + docs/experiments/gate-divergence.md (cross-provider agreement scaffold).
  • ADR 0004 honesty note: prose-gate reliability is empirical.

Changed

  • Positioning: “writable by non-programmers” softened to prose-first / readable; production needs developer judgment for tools, hooks, and untrusted inputs.

[0.5.0] — 2026-07-16

Added

  • Conformance suite (ADR 0009) — conformance/cases/*.yaml: implementation-neutral cases (machine + scripted LLM + expected outcome) that pin the language semantics; any second interpreter must pass them with its own runner. Reference runner in tests/test_conformance.py (15 cases).
  • mklang lint — check plus static analysis: dead gates after otherwise, repair-only states, outputs nobody reads (terminal/judged states exempt), template roots nothing provides (--strict exits 1 on findings).
  • Provider adapters as entry-point plugins — group mklang.providers (factory (ProviderConfig) -> LLM); builtin anthropic, unknown names fall back to the OpenAI-compatible adapter. Completes the plugin story (tools/hooks/providers).
  • Gated live smoke tests (tests/test_live.py) — opt-in via MKLANG_LIVE=1, provider-agnostic: they run the config's active provider (override with MKLANG_LIVE_PROVIDER) and skip when its key is missing. All providers, Anthropic included, share the same path — no provider-specific test code.
  • CI + docs site — extended GitHub Actions workflow (tests, ruff, schema + semantic checks, lint, build, gated live smoke on main) and an mkdocs-material site assembled from the repo's canonical markdown (scripts/build-docs.sh, deployed to GitHub Pages).

Changed

  • SPEC termination paragraph: the END-reachability validator is enforced (it already was — the prose still said "SHOULD").
  • Packaging metadata: classifiers, corrected repository URLs, author contact.

[0.4.0] — 2026-07-16

Added

  • Human-in-the-loop (ADR 0008) — with --hitl (requires --checkpoint), a fired escalate gate suspends at the handler state instead of just routing: the envelope records reason: "escalated" and hitl: true. Reply via mklang resume ck.json --set human.reply="…" — values land in the innermost frame's context so the handler can interpolate {{human.reply}}. Library API: run(..., escalate_suspend=True); mutate frames[-1]["ctx"] before resuming. Default off — escalate-as-routing (tier cascades) is unaffected; escalate to END and fan-out branches never suspend. Language unchanged (spec stays 0.2).

[0.3.0] — 2026-07-16

Added

  • Resumable runs / checkpoints (ADR 0007) — opt-in: with --checkpoint PATH, budget exhaustion (budget-exhausted / cost-exhausted) suspends instead of halting and writes a JSON checkpoint (frames = blackboard + position + spend per call level, machine sha256). New subcommand mklang resume <checkpoint> (--max-tokens, --machine, --force) continues as if uninterrupted — golden round-trip tested, nested call included. New RunResult status "suspended" with frames; library API run(..., suspendable=, resume=); CLI exit code 3. Fan-out branches never suspend. Language unchanged (spec stays 0.2).

Fixed

  • Docs drift pass: SPEC pseudo-schema includes hook / hooks:; comparison table and philosophy updated for host hooks; ADR 0002/0004 no longer refer to code-hooks as future-only; ROADMAP test count aligned (~70).
  • Stale __version__ in mklang/__init__.py (was pinned at 0.2.0).

[0.2.2] — 2026-07-16

Added

  • Code-hook gates — optional hook: <name> on a gate evaluates a host predicate (context, output) -> bool without the LLM (ADR 0006). Top-level hooks: declarations; CLI builtins (auto_approve_ok, …); example hook_gates.mk. Trace records gate_via: hook|llm|otherwise.
  • Tool / hook plugin registry — entry-point groups mklang.tools and mklang.hooks; load_tool_registry() / load_hook_registry() merge builtins with third-party plugins (later keys win). Documented in CONTRIBUTING / patterns.

Changed

  • Default runtime provider is DeepSeek (active: deepseek in config/runtime.example.yaml); README quickstart and status aligned. Live smoke re-verified on DeepSeek (expense_approval.mk → done).

[0.2.1] — 2026-07-16

Correctness hardening and multi-provider polish on top of the v0.2 core.

Fixed

  • Sub-machine halt propagation — a call whose child halts (budget, fail, …) now halts the parent as call-failed: <child-error> with nested sub_trace, instead of continuing as done with result=None.
  • Judge sees reasoning — when reason: true, the private chain-of-thought is passed to LLM.judge (SPEC §4.5 / §6), not only recorded in the trace.
  • Anthropic adapter parity — transient retry with backoff, wrap API failures as ProviderError, apply temperature when thinking is off, structured JSON judge (shared parse_choice with OpenAI-compat).
  • Pre-run tier validation — mklang run rejects machines that need a tier missing from the provider map; engine KeyError messages name the missing tier.
  • Shared cost_budget across call — sub-machines inherit the remaining token budget (no unbounded child spend while the parent still looks under budget).
  • Judge unparseable is no longer silent — adapters raise JudgeUnparseable; the engine soft-falls back only to an eligible otherwise (trace: judge_fallback), else halts with judge-unparseable.
  • over missing path / wrong type — hard error (empty list still OK per SPEC).
  • Fan-out branch call halt — preserves sub_trace and child token usage.
  • Engine exception-safety (clean halt, isolated fan-out branches); empty-eligible no longer crashes; --set accepts JSON (lists for over); load_registry skips malformed siblings; .env discovered from cwd.

Added

  • Formal tool states — a state can invoke a host-registered callable so tool observations re-enter the context (real ReAct, not prose-simulated). Optional top-level tools: block; built-in demo tools (calc, search).
  • Cost accounting — per-step token usage in the trace, a run total, and an optional cost_budget (halt cost-exhausted).
  • Error taxonomy — refusal, provider-error, call-failed, judge-unparseable halt reasons; typed adapter exceptions (CallFailed, JudgeUnparseable, …).
  • Structured-output judge — OpenAI-compatible and Anthropic adapters judge via JSON {"choice": N} with a regex fallback path in parse_choice.
  • Per-tier params applied to the model (effort / thinking / reasoning_effort), best-effort with drop-on-error; pre-run validation in mklang run; richer mklang check (dead states, unproduced result, catch-all warning, version advisory).
  • Schema bundled as package data; mklang: "0.2" field; transient-error retry.
  • Apache-2.0 LICENSE, CONTRIBUTING.md, this changelog.
  • Quality: golden-trace and cookbook-conformance tests; Anthropic adapter unit tests (params / refusal / usage / retry / judge). Live Anthropic e2e still deferred (no ANTHROPIC_API_KEY in the release environment). Live-tested path remains DeepSeek.
  • Docs: SPEC header aligned to 0.2; ROADMAP shipped items synced.

[0.2.0] — core v0.2 + reference interpreter

Added

  • Language core v0.2: reason (traced chain-of-thought), accumulate (list-append), fan-out (sample / over), sub-machine call, top-level result.
  • Patterns cookbook (SPEC.md §10) mapping CoT / ReAct / Reflexion / Self-consistency / Tree-of-Thought / Plan-Execute / Debate / Map-Reduce / Router / speculative cascade.
  • Reference interpreter (src/mklang/): loader + validator, {{}} interpolation, multi-provider LLM adapters (native Anthropic + generic OpenAI-compatible), run loop, nested trace, mklang run / mklang check CLI. Live-tested on DeepSeek.
  • JSON Schema oneOf {generative | call}; examples self_consistency, map_reduce (+ summarize_doc), react.

[0.1] — language definition

Added

  • The mklang concept: an LLM-driven state machine where each state has four faces (structure, prompt, execution, gates), gates are transitions, and the LLM is the runtime. Provider-agnostic capability tiers (fast / balanced / reasoning).
  • SPEC.md, JSON Schema, multi-provider runtime config, examples triage, research, expense_approval.