UtterPlan

UtterPlan is the canonical, engine-independent semantic compiler from one SSMD document (or explicitly selected plain-text document) to an executable speech plan. It produces deterministic prepared text, paragraph-local flow units, safe boundary opportunities, authored pause intents, and segment-local semantics, portable document metadata, and typed directives for independent downstream consumers such as Readio, VoiceRender, and other FlowPlan users. Its book commands read the SSMDBook manifest only for chapter discovery, never modify the manifest or source chapters, and write derived plans to separate directories. It uses TTSReady for written-to-spoken preparation and stops before G2P, synthesis, and audio.

CLI

Compile literal text directly:

utterplan compile "Doctor Smith bought 5 kg." --input-format plain --language en-us

Compile a file to a plan file:

utterplan compile examples/chapter.ssmd -o chapter.utterplan.toml

SSMD header language is authoritative, so --language is optional when it is present. Otherwise pass --language as the fallback; plain input always requires a language. --language never forces a language over SSMD semantics.

Use stdin and shell pipelines:

cat examples/chapter.ssmd | utterplan compile --lang en-us --input-format ssmd > chapter.utterplan.toml

Compile independent documents incrementally; every successful plan is saved immediately, and ordinary failures do not discard earlier outputs:

utterplan compile-many examples/*.ssmd --output-dir build/plans

This writes one .utterplan.toml per source plus an atomically refreshed compile-report.toml. Terminal diagnostics default to warnings; --diagnostics all also prints informational records, while --diagnostics none suppresses non-failure details. Failures are always reported, and the operational report retains every diagnostic. Use --fail-fast to skip later inputs after a failure, --force to replace existing plans, or --report PATH to choose another report location.

Compile a selected chapter range directly from an editable SSMDBook workspace:

cd "Platform Decay - Martha Wells.ssmdbook"

utterplan compile-book chapters --chapters 5-17

The command reads the workspace manifest to discover chapters and writes independent v7 plans and a report under utterplan/:

utterplan/
├── compile-report.toml
├── chapter-0005.utterplan.toml
├── chapter-0006.utterplan.toml
├── ...
└── chapter-0017.utterplan.toml

Omit --chapters to compile all manifest chapters. Use comma-separated source-number selections for non-contiguous ranges, for example utterplan compile-book chapters --chapters 1,3-5. --diagnostics warnings|all|none defaults to warnings; failures are always shown and reports retain complete diagnostics. The book root itself is also accepted as input; see the SSMDBook guide.

From an SSMDBook to RenderPlans

UtterPlan keeps one canonical semantic plan per chapter. A RenderProfile is a separate renderer configuration; create and validate it with VoiceRender, then project the selected saved plans into a profile-specific RenderPlan collection:

voicerender profile create \
  --engine piper \
  --target en_US-amy-medium \
  --language en-US \
  --offline \
  --output narration.renderprofile.toml
voicerender profile validate narration.renderprofile.toml

utterplan compile-book . --chapters 5-17
utterplan render-book . --chapters 5-17 --profile narration.renderprofile.toml

The book's utterplan/ directory remains the shared semantic source. The new command writes independent renderer-specific plans into a deterministic variant:

renderplan/
└── narration--<profile-fingerprint>/
    ├── renderprofile.toml
    ├── renderplan-set.toml
    ├── render-report.toml
    ├── chapter-0005.renderplan.toml
    └── ...

The variant label comes from the profile filename by default; its suffix is the first 12 hexadecimal characters of the canonical RenderProfile profile_id. Changing identity-bearing profile semantics selects a different directory, so multiple voices or planning policies can coexist without replacing one another. Each variant snapshots the canonical profile; renderplan-set.toml records its full identity, source profile reference, and chapter plan IDs. --variant changes the human label without removing the fingerprint, and --output-root changes the collection root while retaining the automatic variant directory.

render-book consumes only the existing schema-v7 UtterPlans and shared RenderProfile/RenderPlan contract. VoiceRender is not required to run it: VoiceRender creates or refreshes engine-backed profiles, then preflights and renders the resulting RenderPlans. The single-file utterplan render-plan command remains the low-level projection and deterministic replan primitive.

When VoiceRender reports preflight.replan, use the new replan-book command to refine the exact active chapter plan. The operation reads the RenderProfile snapshot from the selected variant, writes a fingerprinted child RenderPlan, and updates only that chapter's active set entry. It does not replace the parent plan or rerun initial projection:

# VoiceRender measures the active plans; suppose chapter 5 returns preflight.replan.
voicerender render-book . \
  --variant narration4--28f616b6fe3b \
  --chapters 5 \
  --emphasis-policy defer-to-compose

utterplan replan-book . \
  --variant narration4--28f616b6fe3b \
  --chapters 5

# Measure/render the newly active child. Repeat these last two commands if it
# still reports preflight.replan; each cycle must use feedback for the active plan.
voicerender render-book . \
  --variant narration4--28f616b6fe3b \
  --chapters 5 \
  --emphasis-policy defer-to-compose

Use the exact variant directory name (including its profile fingerprint). replan-book searches preflight-recheck.toml before preflight.toml and refuses stale feedback, so a report for a parent can never be applied to its child. The single-file render-plan --previous ... --preflight ... operation remains available for low-level replanning.

This orchestration does not add a splitter, renderer-specific capacity estimate, or engine dependency. VoiceRender supplies preflight measurements and remains responsible for synthesis and audio composition.

Related packages: RenderPlan defines the shared profile and plan contracts; VoiceRender creates engine-backed profiles and performs preflight and synthesis.

The CLI also provides:

utterplan --version
utterplan validate chapter.utterplan.toml
utterplan inspect chapter.utterplan.toml --segment 0
utterplan inspect chapter.utterplan.toml --boundaries --tokens
utterplan explain chapter.utterplan.toml --trace chapter.trace.toml
utterplan inspect-trace chapter.trace.toml --preparation --boundaries
utterplan inspect-attempt chapter.attempt.toml --issues
utterplan preview chapter.utterplan.toml --segments 58-62 --chunk-by clause --pause-policy automatic
utterplan render-plan chapter.utterplan.toml --profile voice.renderprofile.toml -o chapter.renderplan.toml --explain

explain presents executable flow as a human-readable speech plan. Use compile --trace PATH to retain optional compiler provenance; explain --trace PATH and inspect-trace read that sidecar separately from the plan.

render-plan projects only current schema-v7 FlowPlans into the shared RenderPlan contract. Replanning requires both the exact previous RenderPlan and its matching preflight report; UtterPlan refines only failed speech occurrences and does not calculate renderer-specific metrics.

inspect-attempt reads the separate utterplan.planning-attempt.v1 TOML artifact, not a canonical plan. Use it to review renderability issues and safe repair assessments on blocked planning outcomes; such candidates remain inspect-only drafts. Canonical plan output is TOML (.utterplan.toml) and is written to stdout when no output file is supplied. Status messages use stderr, and existing output files require --force. Safe punctuation repair is the default; use --renderability strict to reject every repair opportunity.

SSMD source contract

UtterPlan accepts SSMD 0.9 syntax only. Use document_format="ssmd" or --input-format ssmd to compile canonical unversioned fragments as SSMD 0.9. Automatic detection recognizes .ssmd, .ssmd.md, and Markdown files with an SSMD version header; ordinary Markdown remains plain text.

Migrate older SSMD source before compilation with the SSMD project's migration command:

ssmd migrate old.ssmd --to 0.9

utterplan migrate handles only serialized plan data; v6-to-v7 migration refuses with migration.recompile_required when the saved plan cannot prove complete boundary coverage. Recompile the original source to produce a current plan. It does not migrate SSMD source. Normal plan loading is TOML-only: FlowPlan.load() and plan-inspection commands reject JSON rather than auto-detecting it.

Planning defaults

The CLI and Python planner default to best-effort spaCy enrichment (auto). UtterPlan prefers an already-installed compatible model in sm, md, lg, trf order; if spaCy or every compatible local model is unavailable, planning continues with deterministic fallback tokens. UtterPlan never downloads models. Use --spacy off or LinguisticsConfig(use_spacy=False) to opt out, or request an explicit tier to require that local model.

Python PlannerConfig defaults to document_format="plain"; set it to "ssmd" when a Python string contains SSMD source.

Python PlannerConfig.renderability_mode also defaults to safe punctuation-only repair; choose "strict" to reject every repair opportunity. Neither mode guesses a symbol's pronunciation or crosses semantic blockers.

V7 token.span, pos, tag, lemma, and morph describe the prepared segment.text and are the downstream linguistic context, not engine/model token counts; consumers should not retokenize or rerun spaCy. Optional replacement.span / replacement.source records compact preparation provenance (for example, A R T from ART): spans index final prepared segment text, while full source coordinates and maps remain in the optional trace sidecar. Replacement provenance does not change executable hashes or synthesis inputs.

Python API

from utterplan import PlannerConfig, FlowPlan, compile_document

ssmd_source = """---
ssmd_version: "0.9"
language: en-GB
---
Hello [world]{emphasis="strong"}.
"""
result = compile_document(
    ssmd_source,
    input_format="ssmd",
    config=PlannerConfig(language="en-us"),  # fallback; header language wins
    trace=True,
)
plan = result.plan
assert result.trace is not None
plan.save("example.utterplan.toml")
assert FlowPlan.load("example.utterplan.toml") == plan

compile_document is the stable public one-document API shared by consumers. The immutable CompileResult contains the semantic plan, diagnostics, and optional explanatory trace. Trace is not serialized in the plan and does not affect its identity. Plain text must be explicitly selected in Python and always requires a language fallback. Existing UtterancePlanner.plan remains supported and returns only the plan; TOML is the portable persistence and interchange format.

The optional RenderPlan producer consumes the stored prepared plan directly:

from renderplan.codec import load_profile, save_plan
from utterplan import FlowPlan, build_render_plan

source = FlowPlan.load("chapter.utterplan.toml")
profile = load_profile("voice.renderprofile.toml")
render_plan = build_render_plan(source, profile)
save_plan(render_plan, "chapter.renderplan.toml")

Use build_render_plan(..., previous_plan=previous, preflight=report) for deterministic refinement; both values are required together. The RenderPlan path rejects historical UtterPlan schemas and does not depend on a renderer or audio runtime. See the RenderPlan CLI and Python API guides.

For operational progress from a long-running Python plan, pass on_progress to UtterancePlanner.plan, UtterancePlanner.compile, or compile_document. The callback receives typed PlannerProgressEvent objects and does not change the plan:

from utterplan import PlannerConfig, UtterancePlanner

events = []
plan = UtterancePlanner(PlannerConfig(language="en-us")).plan(
    text,
    on_progress=events.append,
)

Callbacks run synchronously and exceptions propagate. See the Python API guide for event fields, model-load events, and reuse behavior.

Renderer-consumer boundary

Renderers consume FlowPlan.flow in order. Each FlowUnit contains local FlowSegment objects with already-prepared speech text, effective language, segment-local linguistic token views, canonical boundary opportunities, authored pause intents, directives, markers, and optional heading level. Token start/end offsets are Python-character indexes into that segment's text; they are never document-global coordinates. FlowUnits are fixed paragraph-local blocks, not renderer chunks; a FlowSegment is not necessarily one TTS call. boundary_before / boundary_after hold safe cut opportunities independently from authored none, strength, or timed pause intents. Consumers may choose sentence, paragraph, or engine-token-budget chunking and native, automatic, or manual pause realization; linguistic token views are not model-token counts.

For renderer-neutral chunk tests and debugging, preview_plan() projects stored text and boundaries without changing the plan:

from utterplan import FlowPlan, preview_plan

plan = FlowPlan.load("chapter.utterplan.toml")
chunks = preview_plan(plan, chunk_by="clause", pause_policy="automatic")

FlowPlan.document carries compact document metadata and FlowPlan.linguistics identifies the analysis provider without retaining provider documents. Compiler source, preparation maps, diagnostics, and renderability details belong only in an optional trace sidecar. Plans contain no phonemes, model token IDs, models, sessions, renderer configuration, provider documents, or audio. UtterPlan does not fetch media or execute extension handlers. The intended dependency direction is:

PyKokoro or another renderer -> UtterPlan

UtterPlan does not depend on PyKokoro, G2P engines, ONNX Runtime, or audio packages. Consumer-specific compatibility tests belong in the consuming renderer repository rather than UtterPlan's test suite.

Documentation

• Getting started
• CLI
• SSMDBook workflows
• Format and schema
• Consumer guide
• Architecture
• Coordinates
• PyKokoro integration
• Python API
• Debugging
• Changelog

Versions

The package version is dynamically derived from Git tags by setuptools-scm. Package version and UtterPlan schema version are independent. Current .utterplan.toml plans use semantic schema v7. Historical JSON Schemas v1–v4 remain immutable; schemas v5, v6, and v7 use versioned TOML/FlowPlan contracts and have no JSON Schema resources.

Schema v5 introduced ordered flow units and segment-local semantics; v6 added optional exact-source provenance. Schema v7 removes renderer-selected root unit and adds canonical safe-boundary opportunities separate from authored pause intents; boundaries participate in v7 executable identity. Older schemas retain sequential data-only migration steps through v6, but v6-to-v7 returns migration.recompile_required because the complete boundary inventory cannot be reconstructed. Migrations never reparse, run NLP, plan, call G2P, render, or process audio.

Development

python -m pip install -e '.[dev,docs]'
python -m pytest -q
ruff check .
mypy utterplan
python -m build
sphinx-build -W --keep-going -b html docs docs/_build/html