From ba5649bcd4fddcb047f7a14221da6d85f76852b0 Mon Sep 17 00:00:00 2001 From: Codeman maintainer Date: Tue, 13 Oct 2026 17:39:36 +0200 Subject: [PATCH] feat(html-view): open network access for rendered pages (owner decision) Owner decision 2026-10-13 (#547): a rendered .html page behaves like a file opened from disk in a browser. It may load scripts, styles, fonts, images and media from any host and make fetch, XHR, WebSocket, beacon and form requests to any host. The /html-view Content-Security-Policy is therefore the `sandbox` directive alone (HTML_VIEW_CSP, now exported and documented): the same sandbox flags as before, never `allow-same-origin`, and no fetch directive. It replaces Codeman's own `default-src 'self'` policy on these responses. Everything that confines a page stays: the opaque origin (no Codeman cookies or document, API writes with `Origin: null` refused, API reads not readable cross-origin), and the capability serving only the page's own folder under every path, symlink, dot, extension and confinement rule. A new test builds the route behind registerSecurityHeaders, as in production, and pins the exact header: one `sandbox` directive with the current flags, no `allow-same-origin`, no `-src` directive. The security architecture, architecture invariants, API reference, CLAUDE.md and the Working With Files wiki page now say what a page can do (reach the network, read its own folder) and cannot do (Codeman's origin, cookies, API, other folders), and that this is the owner's decision. Co-Authored-By: Claude Opus 5.5 (1M context) --- CLAUDE.md | 2 +- docs/api-reference.md | 5 ++-- docs/architecture-invariants.md | 2 +- docs/security-architecture.md | 2 +- docs/wiki/Working-With-Files.md | 10 ++++++- src/web/routes/html-view-routes.ts | 22 +++++++++++++--- test/routes/html-view-routes.test.ts | 39 ++++++++++++++++++++++++++-- 7 files changed, 70 insertions(+), 12 deletions(-) diff --git a/CLAUDE.md b/CLAUDE.md index 26e44cd2..361c118b 100644 --- a/CLAUDE.md +++ b/CLAUDE.md @@ -299,7 +299,7 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph **Prompt uploads** (`POST /api/sessions/:id/paste-image`; client wiring in `image-input.js` and `keyboard-accessory.js`): a pasted file is written to `/.codeman-uploads/` and its path lands on the prompt as unsent text. The folder is IN the workspace because that is the only path identical for a local and a container agent, FLAT because `/.codeman/` would BE the data dir when the workspace is the home directory, and self-ignoring through a `.gitignore` of `*` written ONCE with `wx` (a file already there is the user's and is never overwritten; the user's own ignore file is never touched). ⚠️ The directory names live ONLY in `paste-image-gc.ts` (`UPLOAD_DIR_NAMES`): the pre-move `.claude-images/` receives nothing but stays readable for one release, so the GC sweep and the delete cleanup (through `uploadDirs()`) and the image watcher's ignore filter (reading the names) cover BOTH; retire the legacy entry there, never by hand elsewhere. ⚠️ `uploadDirs()` is async and probes the workspace BOUNDED first (`probePathKind()`, the #516 rule: an `unknown` path is skipped, never touched; the sweep keeps the stall cap and the delete passes `pastCap`), then returns only REAL directories (lstat, so a planted symlink is never one), none that is or contains `getDataDir()` (one strictly inside it only holds uploads and is listed), and none for a remote session, since both consumers delete; the check is made at list time, and the same-user race after it is accepted. A remote (SSH) session is refused (400) before any disk touch: its `workingDir` is the remote path, so the file would land on THIS host where the agent cannot read it. → [architecture-invariants#buffers-uploads-and-terminal-history](docs/architecture-invariants.md#buffers-uploads-and-terminal-history) -**File-path links (terminal + chat)**: a path an agent prints is clickable on BOTH surfaces and opens the file-preview overlay. ⚠️ ONE pattern (`FILE_PATH_LINK_PATTERN` / `absoluteFilePathPattern()` in constants.js) feeds the xterm link provider AND `_linkifyFilePaths()`, a fresh instance per call (`lastIndex`). The chat linkifier walks TEXT NODES with DOM APIs, never rebuilds sanitized markup as a string. ⚠️ An out-of-workspace path goes through the ATTACHMENT routes (`POST /api/sessions/:id/attachments` with `notify: false`), never by widening `file-content`/`file-raw` or `file-stream-manager`'s `tail -f` allowlist. ⚠️ `TEXT_ATTACHMENT_EXTENSIONS` IS `EDITABLE_EXTENSIONS` (never a second list), and widening READ must never widen RUN: `html`/`htm`/`svg` stay download-only, other text is inert `text/plain`+`nosniff`. ⚠️ The ONE place HTML renders is `/html-view//...` (`html-view-routes.ts`, `html-view-capabilities.ts`): `POST /api/sessions/:id/html-view` mints a capability for the file's own directory, every response carries `Content-Security-Policy: sandbox` WITHOUT `allow-same-origin` (opaque origin even as a top-level tab, so the page can never read Codeman or drive its API), and only non-dot, asset-allowlisted files under that directory are served (GET/HEAD only; capabilities revoked with the web-tab ones on logout). That tree is served recursively, so minting is refused for a hidden directory or a broad root (`isBroadHtmlViewRoot`); the preview renders by default and the **Page** pill (or a refused mint) falls through to the source view and its Edit button. Never serve HTML same-origin anywhere else. Tests: `test/routes/html-view-routes.test.ts`. Media extensions are single-sourced in `attachment-registry.ts`. ⚠️ **XLSX previews parse in the BROWSER**, never on the server: `spreadsheet-preview.js` fetches the raw route with `?preview=true` (413 above `MAX_XLSX_BROWSER_PREVIEW_BYTES`, 10 MB) and hands the bytes to `spreadsheet-preview-worker.js`, the only place the pinned `exceljs`/`fflate` vendor bundles load (never on page load). `admitXlsx()` caps the ZIP before ExcelJS runs, counting what ExcelJS will EXPAND as well as what it reads (a merge costs its area, a `` past 16384 is refused, validations are never parsed via `ignoreNodes`, and defined names are never expanded: the worker stubs `_definedNames.model`). ⚠️ The INDEX a row or sheet claims is bounded too, since ExcelJS allocates and walks up to it: a `` outside 1-1048576 and an `xl/workbook.xml` `` above `LIMITS.maxSheetId` (65535) are refused, and `sendTile` reuses the merges read at load (`mergesById`), never `sheet.model`, which rebuilds the whole sheet. ⚠️ The COLUMN index costs the same way (a row's cells live at `_cells[col - 1]`, so one `XFD` cell makes ExcelJS's `eachRow`/`eachCell`/`hasValues` visit 16,384 slots per row): `worksheetMetadata` builds each sheet's row and cell index from the keys that exist (`Object.keys` of `_rows` and `_cells`, skipping falsy and `Null`-type cells as `eachCell({ includeEmpty: false })` does), reads row heights in that pass and merges from `sheet._merges`, and `sendTile` reads cells from that index (`populatedRowsById`); never call ExcelJS's dense `eachRow`/`eachCell` there. `parseThemePalette` returns the default palette for a theme above 64 KB (64 * 1024 characters), since its patterns are quadratic on unclosed tags. ⚠️ Merges are capped per sheet (`LIMITS.maxMergesPerSheet`, 2,000) AND workbook-wide (`LIMITS.maxMerges`, 10,000), refused as `merge-limit` before ExcelJS loads, since ExcelJS's `_mergeCellsInternal` checks each merge against every earlier one on its sheet (quadratic). Every `` in `xl/styles.xml` is read with `readTagAttributes()` and refused (`number-format`) when its decoded `formatCode` is over 255 characters or has a `[` after its last `]`: ExcelJS's `isDateFmt` rescans to the end of the code per unclosed `[` once per numeric cell, and the code is echoed into the notice bar. ⚠️ `formatCellValue` caps every cell's display text at `LIMITS.maxCellTextChars` (1,000, ellipsis, never splitting a surrogate pair) for every value shape (rich text, hyperlink text, formula source, errors), since structured clone copies each tile cell's whole string to the page and the load timeout no longer covers tiles. `richTextPrefix` also visits at most `maxCellTextChars + 1` runs, not only keeps that much text: an empty `` adds nothing, so a shared string of a million empty runs was walked whole per cell, per tile (56 s a tile). ⚠️ Every part ExcelJS parses (all but the pure-bytes `xl/media/.`) is also charged per START TAG against `LIMITS.maxElements` (2,000,000, refused as `element-limit`): ExcelJS builds an object per element in sharedStrings, styles, comments, drawings, VML and tables too, and empty stored blocks pad a deflate stream past the ratio cap, so 8.3M empty `` runs in a 375 KB file cost 570 MB of heap. ⚠️ Admission keys every entry on the name ExcelJS will SEE (`excelJsEntryName()`: JSZip's `.`/`..`/empty-segment resolution, then one leading `/` stripped), refuses two entries that land on one name, and treats anything matching ExcelJS's UNANCHORED `xl/worksheets/sheet.xml` as a worksheet, so `/xl/...` or `xl/./...` cannot skip a counter, and ExcelJS parses only a STORE-only archive rebuilt from the entries admission inflated (`buildAdmittedArchive()`), never the fetched bytes; cell text goes through `textContent`, formulas are never evaluated. Bumping either package or editing the worker/core changes `SPREADSHEET_ASSET_VERSION`, which `npm run check:public-assets` pins. xls/ods stay download-only. → [architecture-invariants#file-path-links-terminal--response-viewer](docs/architecture-invariants.md#file-path-links-terminal--response-viewer) +**File-path links (terminal + chat)**: a path an agent prints is clickable on BOTH surfaces and opens the file-preview overlay. ⚠️ ONE pattern (`FILE_PATH_LINK_PATTERN` / `absoluteFilePathPattern()` in constants.js) feeds the xterm link provider AND `_linkifyFilePaths()`, a fresh instance per call (`lastIndex`). The chat linkifier walks TEXT NODES with DOM APIs, never rebuilds sanitized markup as a string. ⚠️ An out-of-workspace path goes through the ATTACHMENT routes (`POST /api/sessions/:id/attachments` with `notify: false`), never by widening `file-content`/`file-raw` or `file-stream-manager`'s `tail -f` allowlist. ⚠️ `TEXT_ATTACHMENT_EXTENSIONS` IS `EDITABLE_EXTENSIONS` (never a second list), and widening READ must never widen RUN: `html`/`htm`/`svg` stay download-only, other text is inert `text/plain`+`nosniff`. ⚠️ The ONE place HTML renders is `/html-view//...` (`html-view-routes.ts`, `html-view-capabilities.ts`): `POST /api/sessions/:id/html-view` mints a capability for the file's own directory, every response carries `Content-Security-Policy: sandbox` WITHOUT `allow-same-origin` (opaque origin even as a top-level tab, so the page can never read Codeman or drive its API) and with NO fetch directive (open network, owner decision 2026-10-13: never restrict it or add `allow-same-origin` without the owner), and only non-dot, asset-allowlisted files under that directory are served (GET/HEAD only; capabilities revoked with the web-tab ones on logout). That tree is served recursively, so minting is refused for a hidden directory or a broad root (`isBroadHtmlViewRoot`); the preview renders by default and the **Page** pill (or a refused mint) falls through to the source view and its Edit button. Never serve HTML same-origin anywhere else. Tests: `test/routes/html-view-routes.test.ts`. Media extensions are single-sourced in `attachment-registry.ts`. ⚠️ **XLSX previews parse in the BROWSER**, never on the server: `spreadsheet-preview.js` fetches the raw route with `?preview=true` (413 above `MAX_XLSX_BROWSER_PREVIEW_BYTES`, 10 MB) and hands the bytes to `spreadsheet-preview-worker.js`, the only place the pinned `exceljs`/`fflate` vendor bundles load (never on page load). `admitXlsx()` caps the ZIP before ExcelJS runs, counting what ExcelJS will EXPAND as well as what it reads (a merge costs its area, a `` past 16384 is refused, validations are never parsed via `ignoreNodes`, and defined names are never expanded: the worker stubs `_definedNames.model`). ⚠️ The INDEX a row or sheet claims is bounded too, since ExcelJS allocates and walks up to it: a `` outside 1-1048576 and an `xl/workbook.xml` `` above `LIMITS.maxSheetId` (65535) are refused, and `sendTile` reuses the merges read at load (`mergesById`), never `sheet.model`, which rebuilds the whole sheet. ⚠️ The COLUMN index costs the same way (a row's cells live at `_cells[col - 1]`, so one `XFD` cell makes ExcelJS's `eachRow`/`eachCell`/`hasValues` visit 16,384 slots per row): `worksheetMetadata` builds each sheet's row and cell index from the keys that exist (`Object.keys` of `_rows` and `_cells`, skipping falsy and `Null`-type cells as `eachCell({ includeEmpty: false })` does), reads row heights in that pass and merges from `sheet._merges`, and `sendTile` reads cells from that index (`populatedRowsById`); never call ExcelJS's dense `eachRow`/`eachCell` there. `parseThemePalette` returns the default palette for a theme above 64 KB (64 * 1024 characters), since its patterns are quadratic on unclosed tags. ⚠️ Merges are capped per sheet (`LIMITS.maxMergesPerSheet`, 2,000) AND workbook-wide (`LIMITS.maxMerges`, 10,000), refused as `merge-limit` before ExcelJS loads, since ExcelJS's `_mergeCellsInternal` checks each merge against every earlier one on its sheet (quadratic). Every `` in `xl/styles.xml` is read with `readTagAttributes()` and refused (`number-format`) when its decoded `formatCode` is over 255 characters or has a `[` after its last `]`: ExcelJS's `isDateFmt` rescans to the end of the code per unclosed `[` once per numeric cell, and the code is echoed into the notice bar. ⚠️ `formatCellValue` caps every cell's display text at `LIMITS.maxCellTextChars` (1,000, ellipsis, never splitting a surrogate pair) for every value shape (rich text, hyperlink text, formula source, errors), since structured clone copies each tile cell's whole string to the page and the load timeout no longer covers tiles. `richTextPrefix` also visits at most `maxCellTextChars + 1` runs, not only keeps that much text: an empty `` adds nothing, so a shared string of a million empty runs was walked whole per cell, per tile (56 s a tile). ⚠️ Every part ExcelJS parses (all but the pure-bytes `xl/media/.`) is also charged per START TAG against `LIMITS.maxElements` (2,000,000, refused as `element-limit`): ExcelJS builds an object per element in sharedStrings, styles, comments, drawings, VML and tables too, and empty stored blocks pad a deflate stream past the ratio cap, so 8.3M empty `` runs in a 375 KB file cost 570 MB of heap. ⚠️ Admission keys every entry on the name ExcelJS will SEE (`excelJsEntryName()`: JSZip's `.`/`..`/empty-segment resolution, then one leading `/` stripped), refuses two entries that land on one name, and treats anything matching ExcelJS's UNANCHORED `xl/worksheets/sheet.xml` as a worksheet, so `/xl/...` or `xl/./...` cannot skip a counter, and ExcelJS parses only a STORE-only archive rebuilt from the entries admission inflated (`buildAdmittedArchive()`), never the fetched bytes; cell text goes through `textContent`, formulas are never evaluated. Bumping either package or editing the worker/core changes `SPREADSHEET_ASSET_VERSION`, which `npm run check:public-assets` pins. xls/ods stay download-only. → [architecture-invariants#file-path-links-terminal--response-viewer](docs/architecture-invariants.md#file-path-links-terminal--response-viewer) **Filesystem path picker** (Link Existing "Browse" + the mobile keyboard's `📁 Path` key): lazy one-directory browsing via `GET /api/filesystem/browse`, with `GET /api/filesystem/preview` for the tapped file. Inserts the path **without** Enter, so the prompt is never submitted; the sibling `⌫ All` key clears only the unsent prompt and must never send the agent's `/clear`. ⚠️ This is a **second file-serving surface and inherits neither the attachment confinement nor its ownership scoping** — it allowlists Home, `CASES_DIR`, `/mnt/d` and `CODEMAN_FILE_PICKER_ROOTS`, blocks sensitive trees, and rejects symlink escapes **after** `realpath`. ⚠️ The optional `sessionId` is an ownership boundary that must be `canAccessOwned`-checked by hand (it does not go through `findSessionOrFail`), and in multi-user mode a non-admin gets only their own `userSpacePath` as a root: per-user spaces live INSIDE `homedir()`, so a `Home` root exposes every other user's workspace. Previews go through the same global conversion limiter, and Markdown/TXT/JSON are served as inert `text/plain`. → [architecture-invariants#filesystem-path-picker](docs/architecture-invariants.md#filesystem-path-picker) diff --git a/docs/api-reference.md b/docs/api-reference.md index 1bc6fae2..5dc62467 100644 --- a/docs/api-reference.md +++ b/docs/api-reference.md @@ -610,8 +610,9 @@ csv, md, svg and common image, font, wasm, audio, video and PDF types), never outside the folder, never a blocked tree, and, for a folder outside the workspace, not while `attachmentConfineToWorkspace` is on. Every response carries `Content-Security-Policy: sandbox allow-scripts allow-forms allow-popups allow-modals allow-downloads` -(never `allow-same-origin`, so the page cannot read Codeman's document, cookies or -API, even opened as a top-level tab), `Cache-Control: no-store`, +as its whole policy (never `allow-same-origin`, so the page cannot read Codeman's +document, cookies or API, even opened as a top-level tab; and no fetch directive, so +by the owner's decision the page may load from and send requests to any host), `Cache-Control: no-store`, `Referrer-Policy: no-referrer` and `Access-Control-Allow-Origin: *`. A `Range` request is answered with `206` + `Content-Range` (`416` past the end), like `file-raw`. Every refusal is a plain-text `404 Not found`; with a password set, an diff --git a/docs/architecture-invariants.md b/docs/architecture-invariants.md index 640d53d4..8a4b5e20 100644 --- a/docs/architecture-invariants.md +++ b/docs/architecture-invariants.md @@ -373,7 +373,7 @@ A file path an agent prints is a link on both surfaces it can appear on, and cli ⚠️ **The terminal routes an out-of-workspace path to the preview, not the log viewer.** The log viewer spawns `tail -f` and allows only the workspace, `/var/log` and `~/logs`, so an external `.log`/`.json`/code path answered `Path must be within working directory or allowed log directories` while the SAME path clicked in the response viewer previewed fine. `activate()` now checks `_isExternalPreviewPath` alongside `previewsInFileViewer`. In-workspace text keeps the tail viewer, which is the point of it (live follow), except markdown (`.md`/`.markdown`, in `FILE_PREVIEW_EXTENSIONS` since the owner's 2026-10-13 decision, rendered as a document) and `.html`/`.htm` (`rendersAsPage()`, rendered as a page, see below), which always go to the preview; nothing widened `file-stream-manager`'s allowlist, so no `tail -f` is spawned on an arbitrary host path. -**Text reuses the edit-mode allowlist; markup stays download-only.** `TEXT_ATTACHMENT_EXTENSIONS` IS `EDITABLE_EXTENSIONS` (`config/file-editing.ts`) rather than a second curated list that would drift from it: if the viewer would open a file for editing inside the workspace, the same file outside it can be read. The justification for widening is that the agent in the session can already `cat` any of these and the picker already previews them, so the suffix was never the confidentiality gate; the path guard is (sensitive-file blocklist, `/root` and `/etc` trees, realpath first). ⚠️ Two consequences had to be handled at the same time: `~/.codeman*/state.json` joined `isSensitivePath` (it persists `SessionState.envOverrides`, and the env allowlist admits key-shaped names like `GEMINI_API_KEY`, so it can hold a live credential), and `html`/`htm` joined `svg` in `serveRawFile`'s **download-only** branch so that widening what can be READ never widens what can RUN on our own origin. Text with no dedicated MIME entry goes out as inert `text/plain; charset=utf-8` + `nosniff`, matching the picker. ⚠️ **The one place HTML renders is `/html-view//...`** (`html-view-routes.ts`, `html-view-capabilities.ts`), never these routes: `POST /api/sessions/:id/html-view` mints a capability for the HTML file's own directory, and every response carries `Content-Security-Policy: sandbox` WITHOUT `allow-same-origin`, so the page is opaque-origin even as a top-level tab and cannot read Codeman or drive its API. The directory is served recursively to the page's scripts (non-dot, asset-allowlisted, realpath-confined, blocklist applied, GET/HEAD only; the dot and extension rules run on the requested name AND on the symlink-resolved target, or a `cfg.json -> .git/config` link would serve the git config), which is why minting is refused for an HTML file in a hidden directory (for a file inside the workspace, a hidden directory below the workspace root, so a workspace that itself lives under one still renders) or directly in a broad root (`/`, home, `/tmp`, `/var/tmp` and `$TMPDIR` (named literally, since macOS sets `TMPDIR` in every terminal), the cases and user-space roots, a drive's mount point such as WSL's `/mnt/d`) or in any directory above one of them (`/home`, `/Users`, macOS's `/private`; `isBroadHtmlViewRoot`). A capability minted for a folder outside the workspace records that, and the serving route refuses it per request once `attachmentConfineToWorkspace` is on, the same re-check the attachment serve path makes. The preview renders it by default; the **Page** pill (`htmlRendered`, per-device like `mdRendered`) and any refused mint fall through to the source view with its Edit button. Tests: `test/routes/html-view-routes.test.ts`, the html-view block in `test/webview-auth-exemption.test.ts`, `test/webview-capability-revocation.test.ts`. The by-id text preview is bounded like the workspace one: a `Range` request for the first 512KB (a real partial read, not a discarded 50MB download) plus a 500-line cap, with the footer saying so. +**Text reuses the edit-mode allowlist; markup stays download-only.** `TEXT_ATTACHMENT_EXTENSIONS` IS `EDITABLE_EXTENSIONS` (`config/file-editing.ts`) rather than a second curated list that would drift from it: if the viewer would open a file for editing inside the workspace, the same file outside it can be read. The justification for widening is that the agent in the session can already `cat` any of these and the picker already previews them, so the suffix was never the confidentiality gate; the path guard is (sensitive-file blocklist, `/root` and `/etc` trees, realpath first). ⚠️ Two consequences had to be handled at the same time: `~/.codeman*/state.json` joined `isSensitivePath` (it persists `SessionState.envOverrides`, and the env allowlist admits key-shaped names like `GEMINI_API_KEY`, so it can hold a live credential), and `html`/`htm` joined `svg` in `serveRawFile`'s **download-only** branch so that widening what can be READ never widens what can RUN on our own origin. Text with no dedicated MIME entry goes out as inert `text/plain; charset=utf-8` + `nosniff`, matching the picker. ⚠️ **The one place HTML renders is `/html-view//...`** (`html-view-routes.ts`, `html-view-capabilities.ts`), never these routes: `POST /api/sessions/:id/html-view` mints a capability for the HTML file's own directory, and every response carries `Content-Security-Policy: sandbox` WITHOUT `allow-same-origin`, so the page is opaque-origin even as a top-level tab and cannot read Codeman or drive its API. ⚠️ **Network access is open, by the owner's decision (2026-10-13, #547):** `HTML_VIEW_CSP` is the `sandbox` directive alone, which REPLACES Codeman's own CSP, with no fetch directive, so a page loads scripts, styles, fonts, images and media from anywhere and may fetch, XHR, open WebSockets, send beacons and post forms anywhere, like a file opened from disk. It can read its own folder through the capability and nothing else on this server; it cannot use Codeman's origin, cookies or API, or reach other folders. Never add a fetch directive or `allow-same-origin` without the owner; the exact header is pinned in `test/routes/html-view-routes.test.ts`. The directory is served recursively to the page's scripts (non-dot, asset-allowlisted, realpath-confined, blocklist applied, GET/HEAD only; the dot and extension rules run on the requested name AND on the symlink-resolved target, or a `cfg.json -> .git/config` link would serve the git config), which is why minting is refused for an HTML file in a hidden directory (for a file inside the workspace, a hidden directory below the workspace root, so a workspace that itself lives under one still renders) or directly in a broad root (`/`, home, `/tmp`, `/var/tmp` and `$TMPDIR` (named literally, since macOS sets `TMPDIR` in every terminal), the cases and user-space roots, a drive's mount point such as WSL's `/mnt/d`) or in any directory above one of them (`/home`, `/Users`, macOS's `/private`; `isBroadHtmlViewRoot`). A capability minted for a folder outside the workspace records that, and the serving route refuses it per request once `attachmentConfineToWorkspace` is on, the same re-check the attachment serve path makes. The preview renders it by default; the **Page** pill (`htmlRendered`, per-device like `mdRendered`) and any refused mint fall through to the source view with its Edit button. Tests: `test/routes/html-view-routes.test.ts`, the html-view block in `test/webview-auth-exemption.test.ts`, `test/webview-capability-revocation.test.ts`. The by-id text preview is bounded like the workspace one: a `Range` request for the first 512KB (a real partial read, not a discarded 50MB download) plus a 500-line cap, with the footer saying so. **Media is single-sourced across the two preview paths.** `VIDEO_ATTACHMENT_EXTENSIONS` / `AUDIO_ATTACHMENT_EXTENSIONS` live in `attachment-registry.ts` and are imported by `file-content`'s media classification, so a clip plays identically whether it is in the workspace or reached by id from outside it. They diverged first: the workspace path had its own inline sets and the registry allowlist had no media at all, so a video an agent wrote to `/tmp` was refused as an unsupported type while the same file inside the repo played. ⚠️ Three things have to line up for a player rather than a dead frame: the extension in the allowlist, a **real MIME entry** in `MIME_TYPES` (a `