feat(v1.1.5): files SDK + files:* triggers

Filesystem-backed blob storage as the fifth concrete trigger kind.

- `files::collection(c).{create,head,get,update,delete,list}` Rhai SDK
  (blob in/out; metadata maps; missing-field throws naming the field).
- `FilesService` trait in picloud-shared; `FsFilesRepo` (atomic
  write: temp→fsync→rename→fsync-dir→DB; single-pass SHA-256;
  checksum-verified reads → Corrupted) + `FilesServiceImpl` in
  manager-core. Metadata in Postgres (0018), bytes on disk under
  PICLOUD_FILES_ROOT with 0o700 shard dirs.
- `files:*` trigger kind via the Layout-E pattern (0019: widen both
  CHECKs + files_trigger_details), TriggerEvent::Files (metadata only,
  no bytes), emit_files fan-out, dispatcher arm, admin endpoint
  POST /triggers/files (reuses validate_trigger_target).
- AppFilesRead/AppFilesWrite capabilities → script:read/script:write
  (seven-scope commitment held). AppPubsubPublish reserved for v1.1.6.
- Admin files API (list + delete) + dashboard Files view per app.

Cross-app isolation keyed on cx.app_id at every layer. ~45 new tests
(service in-memory, fs tempdir, bridge integration). No DB required
for the suite. publish_ephemeral and the orphan sweep stay deferred.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/shared/src/files.rs

@@ -0,0 +1,339 @@
+//! `FilesService` — the v1.1.5 filesystem-backed blob store contract.
+//!
+//! Lives in `picloud-shared` (not `executor-core`) so the Rhai bridge,
+//! the manager-core filesystem+Postgres impl, and any in-memory test
+//! impl can all depend on the same trait without dragging
+//! `executor-core` into a Postgres or filesystem dependency.
+//!
+//! Implementations MUST derive every storage `app_id` from `cx.app_id`
+//! — never from a script-passed argument. That is the cross-app
+//! isolation boundary; see `docs/sdk-shape.md`.
+//!
+//! `FilesService` is collection-scoped: scripts get a handle via
+//! `files::collection(name)` and call
+//! `create`/`head`/`get`/`update`/`delete`/`list` on it. The blob bytes
+//! never travel through Postgres or through trigger payloads — the row
+//! is metadata + a SHA-256 checksum; the bytes live on the filesystem.
+
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+use uuid::Uuid;
+
+use crate::SdkCallCx;
+
+/// POSIX-portable filename cap (255 bytes).
+pub const MAX_FILE_NAME_BYTES: usize = 255;
+/// RFC 6838 puts a reasonable media-type ceiling around 127 chars.
+pub const MAX_CONTENT_TYPE_BYTES: usize = 127;
+
+/// Payload for `create` — a brand-new blob. The id is server-generated
+/// (a UUID); scripts never supply it.
+#[derive(Debug, Clone)]
+pub struct NewFile {
+    pub name: String,
+    pub content_type: String,
+    pub data: Vec<u8>,
+}
+
+/// Payload for `update` — replacement bytes plus optional metadata. If
+/// `name` / `content_type` are `None` the prior values are kept.
+#[derive(Debug, Clone)]
+pub struct FileUpdate {
+    pub data: Vec<u8>,
+    pub name: Option<String>,
+    pub content_type: Option<String>,
+}
+
+/// File metadata as scripts and triggers see it. Serialized into
+/// `ServiceEvent.payload` (the blob bytes are NOT included — files are
+/// too big to ship through trigger payloads), and surfaced to Rhai by
+/// `head` / `list`.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct FileMeta {
+    pub id: Uuid,
+    pub collection: String,
+    pub name: String,
+    pub content_type: String,
+    pub size: u64,
+    /// Lowercase hex SHA-256 of the content.
+    pub checksum: String,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+}
+
+/// One page of file metadata from `FilesService::list`. `next_cursor`
+/// is `Some` when more pages exist, `None` when exhausted.
+#[derive(Debug, Clone)]
+pub struct FilesListPage {
+    pub files: Vec<FileMeta>,
+    pub next_cursor: Option<String>,
+}
+
+#[async_trait]
+pub trait FilesService: Send + Sync {
+    /// Create a new blob; returns its server-generated id. Throws on a
+    /// missing required field, an over-limit blob, or an invalid
+    /// collection name.
+    async fn create(
+        &self,
+        cx: &SdkCallCx,
+        collection: &str,
+        new: NewFile,
+    ) -> Result<Uuid, FilesError>;
+
+    /// Metadata only — no body read. `None` if the file is missing.
+    async fn head(
+        &self,
+        cx: &SdkCallCx,
+        collection: &str,
+        id: &str,
+    ) -> Result<Option<FileMeta>, FilesError>;
+
+    /// Full content. `None` if missing. Verifies the stored checksum
+    /// against the bytes on disk and returns `FilesError::Corrupted`
+    /// when they diverge.
+    async fn get(
+        &self,
+        cx: &SdkCallCx,
+        collection: &str,
+        id: &str,
+    ) -> Result<Option<Vec<u8>>, FilesError>;
+
+    /// Replace content (and optionally metadata). Throws `NotFound`
+    /// when the file doesn't exist.
+    async fn update(
+        &self,
+        cx: &SdkCallCx,
+        collection: &str,
+        id: &str,
+        upd: FileUpdate,
+    ) -> Result<(), FilesError>;
+
+    /// Delete by id; returns whether the file was present.
+    async fn delete(&self, cx: &SdkCallCx, collection: &str, id: &str) -> Result<bool, FilesError>;
+
+    /// Cursor-paginated metadata listing (same shape as KV's list).
+    async fn list(
+        &self,
+        cx: &SdkCallCx,
+        collection: &str,
+        cursor: Option<&str>,
+        limit: u32,
+    ) -> Result<FilesListPage, FilesError>;
+}
+
+/// Failure modes surfaced to the Rhai bridge. The bridge converts each
+/// to a Rhai runtime error string; the discriminants exist so internal
+/// callers (admin endpoints, tests) can react more precisely.
+#[derive(Debug, Error)]
+pub enum FilesError {
+    /// Empty collection name, or one containing a path separator / `..`
+    /// / NUL — rejected at the SDK boundary per `docs/sdk-shape.md`.
+    #[error("invalid collection name: {0}")]
+    InvalidCollection(String),
+
+    /// A required field on `create` was missing or empty. The string
+    /// names the field (`name` / `content_type` / `data`).
+    #[error("missing required field: {0}")]
+    MissingField(&'static str),
+
+    /// Blob exceeds the per-file size cap (default 100 MB,
+    /// `PICLOUD_FILES_MAX_FILE_SIZE_BYTES`).
+    #[error("file too large: {size} bytes exceeds limit of {limit} bytes")]
+    TooLarge { size: usize, limit: usize },
+
+    /// Filename exceeds `MAX_FILE_NAME_BYTES`.
+    #[error("file name too long: {0} bytes exceeds 255")]
+    NameTooLong(usize),
+
+    /// Content-type exceeds `MAX_CONTENT_TYPE_BYTES`.
+    #[error("content_type too long: {0} bytes exceeds 127")]
+    ContentTypeTooLong(usize),
+
+    /// `update` on a non-existent file.
+    #[error("file not found")]
+    NotFound,
+
+    /// The bytes on disk no longer match the stored checksum — the
+    /// filesystem corrupted or a backup was misconfigured. The operator
+    /// decides what to do with the metadata-vs-bytes mismatch; the repo
+    /// does NOT auto-delete.
+    #[error("file content corrupted (checksum mismatch)")]
+    Corrupted,
+
+    /// Caller principal lacked the required capability. Only raised when
+    /// `cx.principal.is_some()` — scripts running with `principal: None`
+    /// (public HTTP) operate under script-as-gate semantics and skip
+    /// the capability check.
+    #[error("forbidden")]
+    Forbidden,
+
+    /// Anything else — Postgres unavailable, filesystem I/O error, etc.
+    #[error("files backend error: {0}")]
+    Backend(String),
+}
+
+impl NewFile {
+    /// Validate required fields + length caps at the SDK boundary.
+    /// `data` must be non-empty (v1.1.5 treats an empty blob as a
+    /// missing `data` field — see HANDBACK §7).
+    ///
+    /// # Errors
+    ///
+    /// Returns the field-specific [`FilesError`] for the first failing
+    /// check.
+    pub fn validate(&self, max_size: usize) -> Result<(), FilesError> {
+        if self.name.trim().is_empty() {
+            return Err(FilesError::MissingField("name"));
+        }
+        if self.content_type.trim().is_empty() {
+            return Err(FilesError::MissingField("content_type"));
+        }
+        if self.data.is_empty() {
+            return Err(FilesError::MissingField("data"));
+        }
+        if self.name.len() > MAX_FILE_NAME_BYTES {
+            return Err(FilesError::NameTooLong(self.name.len()));
+        }
+        if self.content_type.len() > MAX_CONTENT_TYPE_BYTES {
+            return Err(FilesError::ContentTypeTooLong(self.content_type.len()));
+        }
+        if self.data.len() > max_size {
+            return Err(FilesError::TooLarge {
+                size: self.data.len(),
+                limit: max_size,
+            });
+        }
+        Ok(())
+    }
+}
+
+impl FileUpdate {
+    /// Validate the replacement bytes + any supplied metadata.
+    ///
+    /// # Errors
+    ///
+    /// Returns the field-specific [`FilesError`] for the first failing
+    /// check.
+    pub fn validate(&self, max_size: usize) -> Result<(), FilesError> {
+        if self.data.is_empty() {
+            return Err(FilesError::MissingField("data"));
+        }
+        if let Some(name) = &self.name {
+            if name.trim().is_empty() {
+                return Err(FilesError::MissingField("name"));
+            }
+            if name.len() > MAX_FILE_NAME_BYTES {
+                return Err(FilesError::NameTooLong(name.len()));
+            }
+        }
+        if let Some(ct) = &self.content_type {
+            if ct.trim().is_empty() {
+                return Err(FilesError::MissingField("content_type"));
+            }
+            if ct.len() > MAX_CONTENT_TYPE_BYTES {
+                return Err(FilesError::ContentTypeTooLong(ct.len()));
+            }
+        }
+        if self.data.len() > max_size {
+            return Err(FilesError::TooLarge {
+                size: self.data.len(),
+                limit: max_size,
+            });
+        }
+        Ok(())
+    }
+}
+
+/// Reject a collection name that is empty or could escape the per-app
+/// files tree. UUID-shaped ids never produce traversal paths, but
+/// collection names come from scripts so they're validated defensively
+/// at both the SDK boundary and the repo.
+///
+/// # Errors
+///
+/// Returns [`FilesError::InvalidCollection`] when the name is empty or
+/// contains `/`, `\`, `..`, or a NUL byte.
+pub fn validate_collection(collection: &str) -> Result<(), FilesError> {
+    if collection.is_empty() {
+        return Err(FilesError::InvalidCollection("must not be empty".into()));
+    }
+    if collection.contains('/')
+        || collection.contains('\\')
+        || collection.contains("..")
+        || collection.contains('\0')
+    {
+        return Err(FilesError::InvalidCollection(format!(
+            "collection {collection:?} must not contain '/', '\\', '..', or NUL"
+        )));
+    }
+    Ok(())
+}
+
+/// Stub used by the test harness so executor-core integration tests
+/// (which don't touch files) can construct a `Services` bundle without
+/// a filesystem or Postgres. Every call returns
+/// `FilesError::Backend("...")` so accidental use surfaces clearly.
+#[derive(Debug, Default, Clone, Copy)]
+pub struct NoopFilesService;
+
+#[async_trait]
+impl FilesService for NoopFilesService {
+    async fn create(
+        &self,
+        _cx: &SdkCallCx,
+        _collection: &str,
+        _new: NewFile,
+    ) -> Result<Uuid, FilesError> {
+        Err(FilesError::Backend("files is not wired in".into()))
+    }
+
+    async fn head(
+        &self,
+        _cx: &SdkCallCx,
+        _collection: &str,
+        _id: &str,
+    ) -> Result<Option<FileMeta>, FilesError> {
+        Err(FilesError::Backend("files is not wired in".into()))
+    }
+
+    async fn get(
+        &self,
+        _cx: &SdkCallCx,
+        _collection: &str,
+        _id: &str,
+    ) -> Result<Option<Vec<u8>>, FilesError> {
+        Err(FilesError::Backend("files is not wired in".into()))
+    }
+
+    async fn update(
+        &self,
+        _cx: &SdkCallCx,
+        _collection: &str,
+        _id: &str,
+        _upd: FileUpdate,
+    ) -> Result<(), FilesError> {
+        Err(FilesError::Backend("files is not wired in".into()))
+    }
+
+    async fn delete(
+        &self,
+        _cx: &SdkCallCx,
+        _collection: &str,
+        _id: &str,
+    ) -> Result<bool, FilesError> {
+        Err(FilesError::Backend("files is not wired in".into()))
+    }
+
+    async fn list(
+        &self,
+        _cx: &SdkCallCx,
+        _collection: &str,
+        _cursor: Option<&str>,
+        _limit: u32,
+    ) -> Result<FilesListPage, FilesError> {
+        Err(FilesError::Backend("files is not wired in".into()))
+    }
+}