Document deployment-managed cache permissions

docs/config.md

@@ -69,6 +69,9 @@ Built-in defaults are:
 
 An empty cache directory in YAML deliberately selects the corresponding
 per-user root. An explicit empty output or debug directory is invalid.
+Selecting a chunk-plan or checkpoint directory does not configure filesystem
+access policy. Cache permissions come from deployment provisioning, process
+umask, setgid inheritance, and default ACLs; see [Operations](operations.md#cache-provisioning).
 
 ## PromptKit Profiles
 
@@ -200,6 +203,8 @@ through **total_llm**. When omitted, it is recalculated from the effective
 **cache.chunk_plans.mode** accepts **auto**, **bypass**, or **refresh**.
 **cache.checkpoints.enabled** is a boolean. The CLI can override the output
 directory and chunk-plan mode for one run; see [CLI reference](cli.md#run).
+Cache directory fields select only locations; Notarius has no cache permission
+field or environment override.
 
 ## Pipelines
 

docs/internal/state.md

@@ -32,11 +32,18 @@ owned by the [Accepted Chunk Map contract](../integrations/chunk-map.md).
 
 `internal/framework/chunkplan` owns source-addressed plan storage, validation,
 and atomic publication. Its store is constructed only when the selected mode is
-not `bypass`.
+not `bypass`. It preserves rooted entry checks while creating new cache roots
+and source-digest directories with requested mode `0777`, then creates an
+atomic temporary file through rooted `O_CREATE|O_EXCL` with requested mode
+`0666` before sync and rename.
 
 `internal/framework/checkpoint` owns checkpoint identity, manifests, payload
 codecs, loader, and recorder. The CLI constructs a recorder whenever checkpoint
 recording is enabled and constructs a loader only for a `--resume` invocation.
+The recorder writes manifest and payload JSON through
+`fileio.WriteJSONWithProcessPermissions`, whose confined atomic writer creates
+new directories with requested mode `0777` and temporary files with requested
+mode `0666` before publication.
 Identity incorporates explicit stable semantic fingerprints collected from
 prepared modules and validators in addition to configuration, input,
 references, runtime overrides, observed LLM profiles, and the LLM runtime's
@@ -86,7 +93,10 @@ and debug-summary JSON.
 canonical operator-facing reason-code reference.
 
 `internal/core/fileio` provides confined atomic file writes used by state
-collaborators. The chunk-plan store retains its stronger entry validation.
+collaborators. Its exact-mode writer remains available to output and debug
+callers; its process-permission writer is used by checkpoints. The chunk-plan
+store retains its stronger rooted entry validation. [Operations](../operations.md#cache-provisioning)
+owns cache mode and provisioning guidance.
 
 The CLI constructs selective-recomputation policy from resolved generated
 artifact dependencies. It forces the selected step and transitive consumers,

docs/operations.md

@@ -50,11 +50,45 @@ directory selects a per-user root:
 
 The field definitions and configuration examples are in [Configuration](config.md).
 On supported Unix systems, output directories and files are created with
-requested modes **0755** and **0644**. Chunk-plan, checkpoint, and debug
-directories and files use **0700** and **0600**. The operating system's umask
-may impose stricter output modes. Cache and debug roots may contain sensitive
-source-derived data, so provision them for one trusted account or service. An
-output bundle can also contain source content when its JSON output enables
+requested modes **0755** and **0644**; debug directories and files use
+**0700** and **0600**. The operating system's umask may impose stricter output
+or debug modes. Chunk-plan and checkpoint caches instead request maximum modes
+of **0777** for new directories and **0666** for new files, including atomic
+temporary files. The kernel applies the service's umask and applicable default
+ACLs when those entries are created.
+
+## Cache Provisioning
+
+Cache locations select where Notarius writes, not who can access them. A
+private service can use a restrictive umask:
+
+~~~sh
+umask 0077
+notarius run example --config /etc/notarius/config.yml --input /srv/input.txt
+~~~
+
+A trusted-group deployment can provision a setgid cache root and use a
+group-oriented umask (or an equivalent default ACL):
+
+~~~sh
+install -d -m 2770 -g notarius-operators /srv/notarius/chunk-plans /srv/notarius/checkpoints
+umask 0007
+notarius run example --config /etc/notarius/config.yml --input /srv/input.txt
+~~~
+
+Setgid and default ACLs control inherited group ownership and access policy;
+Notarius does not copy a parent directory's literal mode bits. Cache state is
+reconstructible but can contain source-derived data, so operators own its
+access and retention policy. Existing cache inodes retain their prior modes
+after an upgrade. Recreate a cache beneath correctly provisioned parents, or
+stop writers and perform a deliberate administrative migration when a
+whole-tree change is required.
+
+Cache publication remains atomic and stored records remain validated. Those
+guarantees do not add cross-process locking or transactional coordination for
+simultaneous writers to one checkpoint identity.
+
+Output bundles can also contain source content when JSON output enables
 evidence publication. Apply an appropriate umask and output-root access policy
 before enabling that option; the requested output modes alone may not be
 suitable for transcript-bearing bundles.

docs/policy/architecture.md

@@ -293,6 +293,15 @@ an invocation that explicitly requests resume. Debug is never a cache input and
 is never created without an explicit request. Pipeline modules receive
 collaborator interfaces and never physical roots.
 
+Deployments own cache access policy. Cache writers request conventional maximum
+creation modes and let the process umask, setgid inheritance, and default ACLs
+determine effective access. Notarius owns the separate safety boundary:
+confined paths, symlink rejection, atomic publication, validation, and
+recovery. It does not chmod, chown, chgrp, or migrate cache entries to impose
+an application policy. This rule applies to chunk-plan and checkpoint cache
+only; output and debug retain their separate contracts. [Operations](../operations.md)
+owns deployment provisioning and retention guidance.
+
 Only accepted, completely validated producer output is reusable checkpoint or
 chunk-plan state. Rejected, structurally invalid, and validation-incomplete
 results cannot become cache or checkpoint inputs, even when a

docs/roadmap/implementation.md

@@ -244,6 +244,8 @@ prompt.
 
 ## Stage 4: Update Canonical Documentation
 
+**Completed:** 2026-09-11
+
 ### Goal
 
 Make the implemented behavior discoverable without duplicating volatile