narratio/docs/config.md

# Configuration Reference

## Purpose

Narratio resolves three YAML documents:

- `pipeline.yml`: pipeline/runtime settings
- `campaign.yml`: campaign identity and stable input defaults
- `session.yml`: session identity, metadata, and audio source selection

## Discovery and Selection

### `pipeline.yml`

When `--config` is omitted, search order is:

1. `/usr/local/etc/narratio/pipeline.yml`
2. `/etc/narratio/pipeline.yml`

### `campaign.yml`

Selection rules:

- if `--campaign-file` is set, use that path;
- else if `--campaign <id>` is set, use `{pipeline.campaigns.root}/{id}/campaign.yml`;
- else use `{pipeline.campaigns.root}/{pipeline.campaigns.default_campaign_id}/campaign.yml`.

### `session.yml`

When `--session` is omitted, local search order is:

1. `/usr/local/etc/narratio/session.yml`
2. `/etc/narratio/session.yml`

If local session discovery fails and a `session_id` is known, Narratio attempts remote session loading from:

- `{root_prefix}/campaigns/{campaign}/sessions/{session_id}/session.yml`

using configured object storage.

The downloaded remote session file is command-scoped: Narratio removes it after
the command finishes and records only the remote object provenance alongside
the durable copied session input.

### Read-only effective pipeline inspection

`narratio config validate` and `narratio config show` use the same `--config`,
`--campaign`, `--campaign-file`, and `--profile` selection rules as pipeline
commands, but do not select, discover, or load a session. They do not read
credential values or create runtime state.

Campaign selection is optional only when the resolved pipeline has no
`scriptorium.artifact_families`. When families are declared, Narratio selects a
campaign through an explicit flag or `pipeline.campaigns.default_campaign_id`,
then parses the campaign-owned party and expands concrete artifacts and any
family publish rules before validation. `config validate` prints the resulting
root, profile, and effective digest. `config show` emits the normalized
effective pipeline YAML, with defaults and concrete expansion included but
composition and family declarations omitted. The [CLI reference](cli.md#config-validate-and-config-show)
owns command syntax and output conventions.

### Identity segments

Campaign IDs (`campaign_id` and `default_campaign_id`), session IDs, previous
session IDs, and Narratio run IDs are opaque portable segments. They must use
only ASCII letters, digits, `.`, `_`, and `-`; empty values, `.`/`..`, path
separators, drive forms, whitespace, control characters, and non-ASCII text are
rejected. Narratio does not trim or rewrite these values. Existing manifests or
remote state with an unsafe legacy identity must be migrated before use.

## Validation and Merge Rules

- YAML decode is strict (`KnownFields(true)`) and accepts exactly one document:
  unknown fields or trailing documents fail load.
- A pipeline file may explicitly import additive YAML fragments through the
  root-only `composition.imports` list. Imported files contribute fields to one
  logical pipeline document; they do not override fields supplied by the root
  or another import.
- A root pipeline may declare named profiles. Exactly one profile is selected
  by an option-aware caller or by `composition.default_profile`; a caller's
  explicit selection takes precedence. Declaring profiles without either form
  of selection is an error.
- Configured timeout and retry-delay durations must be positive. An omitted
  artifact timeout continues to inherit its configured Scriptorium timeout.
- Session files must be concrete; unresolved `{{ ... }}` placeholders fail load.
- Pipeline defaults are applied before validation.
- Campaign and session identities must agree.
- Required stable files (`speakers_file`, `autocorrect_file`, `glossary_file`,
  `party_file`) and the optional `spell_catalog_file` resolve from session
  overrides when provided, otherwise from campaign defaults. An empty or
  omitted session spell-catalog value inherits the campaign value.
- `party_file` is classified when pipeline and campaign configuration are
  combined. A versioned [canonical party](integrations/party.md) is
  campaign-owned, derives the players input internally, and forbids both a
  separate `players_file` and a session `party_file` override. An unversioned
  party remains a bounded legacy input and requires `players_file`; its normal
  campaign/session overrides continue to apply.
- Exactly one audio mode must be configured in session input:
  - local (`audio_dir` or `audio_files`), or
  - S3 (`audio_s3.prefix`).

### Pipeline composition

Large pipeline configurations may be split into explicitly named fragments and
may declare one overlay per selectable profile:

```yaml
composition:
  imports:
    - config/storage.yml
    - config/integrations.yaml
  default_profile: production
  profiles:
    production:
      overlay: profiles/production.yml
    testing:
      overlay: profiles/testing.yml

campaigns:
  root: /usr/local/share/narratio/campaigns
```

Imports are resolved relative to the directory containing the root pipeline
file and are loaded in declaration order. Narratio does not scan directories or
infer fragments. Each import must be a confined regular `.yml` or `.yaml` file:
absolute paths, traversal, symlinks, directories, duplicate files, and an
import of the root pipeline itself are rejected. Only the root pipeline may
contain `composition`; nested composition is rejected.

Composition is additive. A map may be extended by multiple files when every
leaf is distinct, but a scalar, list, or map/list/scalar kind cannot be claimed
more than once, even when the repeated values are identical. Conflict errors
name the full field path and every source that claimed it. The assembled YAML is
then decoded against the normal strict pipeline schema and defaults are applied
once.

Profile names are case-sensitive, non-empty, trimmed, and cannot contain
control characters. If `profiles` is present, it must contain at least one
entry and every entry must contain only an `overlay` path. An explicit profile
selection overrides `default_profile`; unknown and explicitly empty selections
fail. Narratio never selects the first profile implicitly and does not read a
profile selection from the environment.

Every declared overlay is resolved relative to the root pipeline directory and
must satisfy the same confined regular-YAML-file rules as an import. Narratio
parses every declared overlay even when it is not selected, then applies only
the selected one. Maps merge recursively, overlay scalars replace base scalars,
and overlay lists replace base lists completely. Explicit `false`, zero, empty
lists, and empty maps remain meaningful. YAML null cannot delete a value, and
kind changes are rejected. Profiles cannot inherit from or stack with other
profiles, and overlays cannot import files or declare profiles.

After composition, Narratio strictly decodes the result, applies centralized
defaults once, resolves ordinary paths, and computes a deterministic effective
configuration digest. The digest represents the normalized, secret-free
runtime pipeline mapping; it excludes composition declarations, source
provenance, profile identity, and raw environment secret values. Equivalent
effective mappings therefore have the same digest regardless of how fields are
split among the root and imports.

An imported field has the same meaning it would have in a monolithic root
pipeline. In particular, ordinary relative pipeline paths continue to resolve
from the root pipeline directory, not from the importing fragment's directory.

## Minimal Working Configuration

`pipeline.yml`

```yaml
campaigns:
  root: /usr/local/share/narratio/campaigns
  default_campaign_id: sample-campaign
whisperx:
  transcribe_url: https://transcription.example.com/transcribe
```

`campaign.yml`

```yaml
campaign_id: sample-campaign
inputs:
  speakers_file: ./speakers.yml
  autocorrect_file: ./autocorrect.yml
  glossary_file: ./glossary.yml
  players_file: ./players.yml
  party_file: ./party.yml
```

`session.yml` (local audio)

```yaml
session_id: 2026-05-03
inputs:
  audio_dir: ./audio
```

## Secrets Handling

- Do not place raw secrets in YAML.
- Use env var names in config (for example `pipeline.audita.llm_api_key_env`).
- Optionally load credential files from `pipeline.secrets.env_dir`. Each valid
  environment-variable filename supplies one value; trailing CR/LF is removed.
- An existing process environment value takes precedence over a credential file.
- Credential directories and files must not be symlinks and must be regular,
  bounded files (at most 8 KiB per value). On POSIX, provision the directory
  with no group/other access (normally `0700`) and files with no group/other
  access (normally `0600`).
- Commands that need storage/auth load filesystem secrets before constructing adapters.

## Publish Configuration Summary

Publish rules live under `pipeline.publish`.

```yaml
publish:
  enabled: true
  upload_run: true
  outputs:
    - source: narratio.transcript.final_trimmed
      dest: transcripts/final.trimmed.json
      required: true
    - source: narratio.transcript.final_markdown
      dest: transcripts/final.md
      required: true
    - source: narratio.transcript.final_trimmed_markdown
      dest: transcripts/final.trimmed.md
      required: true
    - source: narratio.artifact.session_recap
      dest: artifacts/session_recap.md
      required: true
  locks:
    - source: narratio.artifact.session_recap
      reason: manual post-publish edits
```

Rules:

- `outputs[].source` is required.
- `outputs[].dest` may be omitted when derivable from source.
- extraction sources require an explicit `outputs[].dest` and publish only when
  a rule names that source; the Notarius index and complete bundle are not
  publish sources.
- `outputs[].required` defaults to `true`.
- static locks (`pipeline.publish.locks`) merge with remote locks (`{session_prefix}/locks.yml`), with static locks taking precedence on duplicates.

## Full Schema

### Pipeline

| Field | Type | Required | Default / Rule |
| --- | --- | --- | --- |
| `composition.imports[]` | list of strings | No | explicit additive pipeline fragments relative to the root pipeline directory; `.yml` or `.yaml` regular files only |
| `composition.default_profile` | string | Conditional | selected when profiles exist and no caller explicitly selects one; must name a declared profile |
| `composition.profiles.<name>.overlay` | string | Conditional | required for every declared profile; one confined `.yml` or `.yaml` overlay relative to the root pipeline directory |
| `pipeline.workspace.root` | string | No | `/var/lib/narratio` |
| `pipeline.workspace.cleanup_after_publish` | bool | No | `false` |
| `pipeline.campaigns.root` | string | No | `/usr/local/share/narratio/campaigns` |
| `pipeline.campaigns.default_campaign_id` | string | No | empty |
| `pipeline.secrets.env_dir` | string | No | empty |
| `pipeline.storage.backend` | string | No | `local`; supported values are `local` and `s3` (case-insensitive) |
| `pipeline.storage.s3.bucket` | string | Conditional | required when backend is `s3` and S3 session-audio or publish upload is enabled |
| `pipeline.storage.s3.root_prefix` | string | No | `dnd` |
| `pipeline.storage.s3.region` | string | No | empty |
| `pipeline.storage.s3.endpoint` | string | No | empty |
| `pipeline.storage.s3.force_path_style` | bool | No | `false` |
| `pipeline.storage.s3.access_key_id_env` | string | No | `OBJECT_STORAGE_KEY_ID` |
| `pipeline.storage.s3.secret_access_key_env` | string | No | `OBJECT_STORAGE_KEY` |
| `pipeline.spool.root` | string | No | `/var/spool/narratio` |
| `pipeline.spool.delete_audio_after_publish` | bool | No | `false` |
| `pipeline.cache.root` | string | No | `/var/cache/narratio` |
| `pipeline.cache.s3_audio` | bool | No | `true` |
| `pipeline.publish.enabled` | bool | No | `true` |
| `pipeline.publish.upload_run` | bool | No | `true` |
| `pipeline.publish.outputs[]` | list | No | defaults to final trimmed JSON plus final and final-trimmed Markdown outputs |
| `pipeline.publish.outputs[].source` | string | Yes (per rule) | must reference built-in or configured artifact source |
| `pipeline.publish.outputs[].dest` | string | Conditional | derived if omitted and source supports derivation |
| `pipeline.publish.outputs[].required` | bool | No | `true` |
| `pipeline.publish.locks[]` | list | No | empty |
| `pipeline.publish.locks[].source` | string | Yes (per lock) | must reference supported publish source |
| `pipeline.publish.locks[].reason` | string | No | empty |
| `pipeline.whisperx.transcribe_url` | string | Yes | absolute `http` or `https` URL |
| `pipeline.whisperx.language` | string | No | `en` |
| `pipeline.whisperx.timeout` | duration | No | `30m` |
| `pipeline.whisperx.retries` | int | No | `3` |
| `pipeline.whisperx.retry_delay` | duration | No | `2s` |
| `pipeline.whisperx.concurrency` | int | No | `2` |
| `pipeline.seriatim.binary` | string | No | `seriatim` |
| `pipeline.seriatim.timeout` | duration | No | `10m` |
| `pipeline.seriatim.output_schema` | string | No | `seriatim-intermediate` |
| `pipeline.seriatim.coalesce_gap` | float | No | `3.0` |
| `pipeline.seriatim.report` | bool | No | `true` |
| `pipeline.seriatim.env.overlap_word_run_gap` | float | No | unset |
| `pipeline.seriatim.env.overlap_word_run_reorder_window` | float | No | unset |
| `pipeline.seriatim.env.backchannel_max_duration` | float | No | unset |
| `pipeline.seriatim.env.filler_max_duration` | float | No | unset |
| `pipeline.audita.binary` | string | No | `audita` |
| `pipeline.audita.timeout` | duration | No | `3h` |
| `pipeline.audita.llm_api_key_env` | string | No | empty |
| `pipeline.audita.modules[]` | list[string] | No | empty |
| `pipeline.audita.base_url` | string | No | empty |
| `pipeline.audita.model` | string | No | empty |
| `pipeline.audita.total_llm_concurrency` | int | No | unset |
| `pipeline.audita.proposal_llm_concurrency` | int | No | unset |
| `pipeline.audita.validation_model` | string | No | empty |
| `pipeline.audita.validation_llm_concurrency` | int | No | unset |
| `pipeline.audita.transcript_description` | string | No | empty |
| `pipeline.audita.config_path` | string | No | empty |
| `pipeline.audita.output_schema` | string | No | empty |
| `pipeline.audita.work_dir_retention` | string | No | empty |
| `pipeline.audita.report` | bool | No | `true` |
| `pipeline.normalize.output_path` | string | No | `transcripts/final.json` |
| `pipeline.normalize.output_schema` | string | No | `seriatim-intermediate` |
| `pipeline.normalize.report` | bool | No | `true` |
| `pipeline.trim.enabled` | bool | No | `true` |
| `pipeline.trim.output_path` | string | No | `transcripts/final.trimmed.json` |
| `pipeline.trim.bounds.prompt_id` | string | No | `dnd.session_bounds` |
| `pipeline.trim.bounds.profile_id` | string | No | empty |
| `pipeline.trim.bounds.transcript_input_name` | string | No | `transcript` |
| `pipeline.trim.bounds.output_path` | string | No | `artifacts/session_bounds.json` |
| `pipeline.trim.bounds.timeout` | duration | No | `10m` |
| `pipeline.trim.bounds.render_debug` | bool | No | `false` |
| `pipeline.trim.bounds.render_output_path` | string | Conditional | required when `render_debug` is true |
| `pipeline.trim.seriatim.report` | bool | No | `false` |
| `pipeline.notarius.enabled` | bool | No | `false` |
| `pipeline.notarius.binary` | string | No | `notarius` |
| `pipeline.notarius.config_path` | string | Conditional | required when enabled; relative paths resolve from the pipeline file directory |
| `pipeline.notarius.pipeline_id` | string | Conditional | required when enabled |
| `pipeline.notarius.timeout` | duration | No | `3h`; must be positive |
| `pipeline.notarius.working_directory` | string | No | directory containing resolved `config_path`; relative paths resolve from the pipeline file directory |
| `pipeline.notarius.references` | map[string]string | No | empty; maps normalized Notarius selectors to supported prepared Narratio source IDs; maximum 256 entries |
| `pipeline.notarius.outputs` | map | Conditional | at least one entry when enabled |
| `pipeline.render.enabled` | bool | No | `true` |
| `pipeline.render.format` | string | No | `markdown` (only supported value) |
| `pipeline.render.title` | string | No | empty (falls back to `session.title` when set) |
| `pipeline.render.include_timestamps` | bool | No | `true` |
| `pipeline.render.include_segment_ids` | bool | No | `true` |
| `pipeline.render.include_metadata` | bool | No | `false` |
| `pipeline.scriptorium.binary` | string | No | `scriptorium` |
| `pipeline.scriptorium.config_path` | string | No | empty |
| `pipeline.scriptorium.timeout` | duration | No | `10m` |
| `pipeline.scriptorium.render_debug` | bool | No | `false` |
| `pipeline.scriptorium.artifacts` | map | No | empty |
| `pipeline.scriptorium.artifact_families` | map | No | empty; expands one ordinary artifact per canonical party character |
| `pipeline.notification.mode` | string | No | `noop`; the only supported notification mode until a provider is implemented |

### Notarius Reference Bindings

`pipeline.notarius.references` maps a Notarius CLI selector to a prepared
Narratio source, not to a filesystem path:

```yaml
notarius:
  references:
    glossary: narratio.input.glossary
    party: narratio.input.party
    players: narratio.input.players
    spell_catalog: narratio.input.spell_catalog
```

Supported sources are `narratio.input.party`, `narratio.input.players`,
`narratio.input.glossary`, and `narratio.input.spell_catalog`. Each map entry is
required by its presence: omit a binding when the selected Notarius pipeline
does not need it. A spell-catalog binding additionally requires an effective
campaign or session `spell_catalog_file`.

Selectors accept Notarius's `slot`, `chunk.slot`, `lane.slot`,
`lane.extract.slot`, `lane.merge.slot`, and `lane.normalize.slot` forms.
Narratio trims whitespace around
selectors and their dot-separated components, rejects empty components and
`=`, rejects duplicate normalized selectors, and limits the map to 256 entries.
It validates only selector structure and the prepared source vocabulary;
Notarius owns target-slot declarations and media compatibility.

Before extraction, Narratio resolves every binding from the current prepared
session manifest and streams it into a verified invocation-local snapshot whose
absolute path is passed to Notarius. Missing, unsafe, empty,
changed-during-copy, or checksum-inconsistent prepared evidence fails with
guidance to force `prepare`. Bindings are sorted by normalized selector and are
part of extraction fingerprint and resume identity. See the
[Notarius integration contract](./integrations/notarius.md) for the subprocess
boundary and the [complete example](../examples/pipeline.full.annotated.yml)
for a copyable configuration.

### Notarius Output Entries

For each `pipeline.notarius.outputs.<name>`:

| Field | Type | Required | Rule |
| --- | --- | --- | --- |
| `lane_id` | string | Yes | unique Notarius lane ID |
| `media_type` | string | Yes | exact accepted descriptor media type |
| `schema_id` | string | Yes | exact accepted descriptor schema ID |
| `schema_version` | string | Yes | exact accepted descriptor schema version |
| `module_key` | string | No | exact accepted module key when set |

Output names must match `^[a-z][a-z0-9_]*$` and become selectable sources named
`narratio.extraction.<name>`. Lane IDs must be unique. Every declared output is
required from a successful Notarius result; a missing, rejected, duplicate, or
contract-incompatible lane fails extraction. See the
[complete maintained example](../examples/pipeline.full.annotated.yml) for the
current ten-lane D&D mapping and the [Notarius contract](./integrations/notarius.md)
for compatibility ownership.

### Scriptorium Artifact Entries

For each `pipeline.scriptorium.artifacts.<name>`:

| Field | Type | Required | Rule |
| --- | --- | --- | --- |
| `enabled` | bool | No | `false` if omitted |
| `depends_on[]` | list[string] | No | must reference configured artifact keys; no self-reference; configured graph must be acyclic |
| `render_debug` | bool | No | per-artifact override |
| `prompt_id` | string | Conditional | required when artifact is enabled |
| `profile_id` | string | No | empty |
| `output_path` | string | Conditional | required when enabled; also required when referenced by publish/output/input rules |
| `timeout` | duration | No | artifact override |
| `inputs` | map | No | input key names must be non-empty |
| `vars` | map | No | values must be string or bool; `session_id` is reserved and overwritten by Narratio |

Narratio adds `session_id=narratio-session-<session_id>` to every Scriptorium request for sticky upstream LLM routing. If an artifact config sets `vars.session_id`, Narratio replaces that value before invoking Scriptorium. Use a different variable name if a prompt needs the raw Narratio session ID as content.

Without `--artifacts`, analyze executes enabled configured artifacts. With an
explicit `--artifacts` list, the exact named configured artifacts are the
one-invocation targets even if their `enabled` values are false. Analyze closes
those targets over `depends_on`: a current prerequisite is reused, while a
stale, missing, failed, or legacy prerequisite is rebuilt before its dependent.
Unrelated artifacts are not executed. Named targets and any prerequisite that
may require rebuilding must therefore have valid executable fields. This
override affects analyze planning only; publish uses the list only to filter
configured `narratio.artifact.<name>` output rules.

For each artifact input `pipeline.scriptorium.artifacts.<name>.inputs.<input_name>`:

| Field | Type | Required | Rule |
| --- | --- | --- | --- |
| `source` | string | Yes | built-in runtime source, prepared input source, `narratio.extraction.<name>`, `narratio.artifact.<name>`, or `narratio.previous_session.artifact.<name>` |
| `required` | bool | No | optional input requirement |

`artifact` and `path` are obsolete and rejected by strict configuration
loading. Use the canonical `source` identifier to select the input; Narratio
does not provide adapter-specific input passthrough fields.

### Scriptorium Artifact Families

`pipeline.scriptorium.artifact_families` declares a shared artifact template
for every canonical campaign character. Configuration resolution expands each
family into ordinary `pipeline.scriptorium.artifacts` entries before analyze
planning or Scriptorium invocation. A legacy party cannot be used for a family.

For each `pipeline.scriptorium.artifact_families.<name>`:

| Field | Type | Required | Rule |
| --- | --- | --- | --- |
| `enabled`, `prompt_id`, `profile_id`, `timeout`, `render_debug`, `depends_on`, `inputs`, `vars` | ordinary artifact fields | No | copied to each generated artifact under the corresponding ordinary rules |
| `for_each` | string | Yes | exactly `party.characters` |
| `output_path_pattern` | string | Yes | safe path beneath `artifacts/` with exactly one `{character_id}` token and no other brace syntax |
| `member_vars` | map | No | maps an ordinary Scriptorium variable name to a supported canonical character selector |
| `member_dependencies` | list | No | unique family keys; each generated member depends on the corresponding generated member of each listed family |
| `publish` | map | No | typed family publish policy (`enabled`, `required`, `dest_pattern`) expanded into concrete publish outputs when enabled |

Generated keys are `<family>_<character_id>` and generated output paths must
not collide with explicit artifacts or another generated artifact. Families
expand even when disabled; normal analyze selection still omits disabled
artifacts unless they are explicitly selected by their concrete key.

Supported `member_vars` selectors are `character_id`, `player.name`,
`character.name`, `character.class_summary`, and `character.alias_summary`.
Their resolved values are strings. A member variable may not reuse a static
`vars` name; `session_id` remains owned and overwritten by Narratio as for any
other Scriptorium artifact.

Within a family only, an input source may use
`narratio.member_artifact.<family>`. The referenced family must be named in
that family's `member_dependencies`; resolution rewrites the source to the
corresponding ordinary `narratio.artifact.<family>_<character_id>` source.
This syntax is rejected in explicit artifacts and never reaches runtime stages
or Scriptorium.

### Notifications

Narratio currently supports only `notification.mode: noop`, which is also the
default when the section is omitted. The notify stage performs no delivery in
this mode. Backend, recipient, timeout, and other provider settings are
rejected by strict configuration loading until Narratio has a provider
integration.

### Campaign

| Field | Type | Required | Notes |
| --- | --- | --- | --- |
| `campaign_id` | string | Yes | canonical opaque campaign identity |
| `session_template_file` | string | No | used by `session init` when set |
| `inputs.speakers_file` | string | Yes | stable input default |
| `inputs.autocorrect_file` | string | Yes | stable input default |
| `inputs.glossary_file` | string | Yes | stable input default |
| `inputs.players_file` | string | Conditional | required only with an unversioned legacy `party_file`; forbidden for a canonical party |
| `inputs.party_file` | string | Yes | stable campaign party source; relative paths resolve from `campaign.yml` |
| `inputs.spell_catalog_file` | string | No | optional spell-catalog overlay default; required when a Notarius reference selects `narratio.input.spell_catalog` |

### Session

| Field | Type | Required in session file | Notes |
| --- | --- | --- | --- |
| `session_id` | string | Yes | opaque identity; must match CLI session target when provided |
| `previous_session_id` | string | No | opaque identity; must not equal `session_id` |
| `campaign` | string | No | opaque identity; filled from `campaign_id` during resolve if omitted |
| `date` | string | No | metadata |
| `title` | string | No | metadata |
| `inputs.speakers_file` | string | No | overrides campaign stable input |
| `inputs.autocorrect_file` | string | No | overrides campaign stable input |
| `inputs.glossary_file` | string | No | overrides campaign stable input |
| `inputs.players_file` | string | No | legacy-party override; forbidden for a canonical party |
| `inputs.party_file` | string | No | legacy-party override; forbidden for a canonical campaign party |
| `inputs.spell_catalog_file` | string | No | overrides the optional campaign spell catalog; empty or omitted inherits the campaign value |
| `inputs.audio_dir` | string | Conditional | local audio mode |
| `inputs.audio_files[]` | list[string] | Conditional | local audio mode |
| `inputs.audio_s3.prefix` | string | Conditional | S3 audio mode |

Audio rules:

- configure local mode (`audio_dir` or `audio_files`) or S3 mode (`audio_s3.prefix`), not both.
- `audio_s3` requires `pipeline.storage.backend: s3` and a configured S3 bucket.

### Storage backend selection

`local` is the default and disables remote object-store operations. Configure
`s3` explicitly before supplying `storage.s3`; a populated S3 block does not
select a backend on its own. Unknown backend names and an S3 block paired with
`local` are rejected during configuration validation.

### Previous-session expectation

`previous_session_id` is optional in a session file. When a command supplies
`--previous-session-id`, however, the session file must contain the same value;
an omitted or different value is rejected before the command performs work.

## Maintained Examples

See the [maintained examples index](../examples/README.md) for complete pipeline,
campaign, session, template, and input fixtures. Keep complete copyable files
there rather than duplicating them in this reference.