#1743: protect render sources and refresh proxies safely

docs/agents.md

@@ -4,6 +4,10 @@ Everything in EffectCraft is an engine command with a stable id and JSON params.
 panel gestures, the CLI, the control channel and MCP all go through the same commands, so anything a
 user can do, an agent can do too. There are three ways in:
 
+Render-queue outputs cannot replace footage, proxies or the project file. See
+[render source protection](render-source-protection.md) for aliases, default names and sequence
+limits. This guard does not change ordinary-file overwrite defaults or add another confirmation API.
+
 | Interface | Best for | Needs a window |
 |---|---|---|
 | **MCP** (`effectcraft-cli mcp`) | Claude Code and other MCP clients | no (headless), or yes with `--bridge` |

docs/render-source-protection.md

@@ -0,0 +1,26 @@
+# Render source protection
+
+The render queue refuses an output that would replace footage, an attached proxy, or the
+project file. It checks every output module and segment before dispatching the item. A refused
+item is marked Failed with its reason; other valid queued items can still render. Render logs
+are checked too. No render parameter overrides this protection.
+
+Checks compare normalized paths and native file identities, so an existing symbolic link,
+hard link, junction or Windows short name cannot disguise a source as another output file.
+Source identities are indexed once per check and matching identities are verified. The index
+does not keep file handles open for the lifetime of a long sequence.
+
+Default output names move aside when they would replace a protected file. This also applies to
+Create Proxy: recreating a proxy chooses a new default name and attaches the new proxy, leaving
+the previous proxy file intact. An explicit output path is kept as entered and refused if it
+would replace a protected file.
+
+Image-sequence checks inspect existing frames in the requested range. Skip Existing Files leaves
+existing frames alone. If a frame number appears in a folder name, the checker probes each
+frame separately and refuses ranges over 100,000 frames instead of silently checking a prefix.
+Choose a fixed output folder or a shorter range for those exports.
+
+This guard does not introduce an overwrite flag, confirmation dialog, or changed replacement
+defaults for the CLI, scripts or MCP. Replacement consent and staging ordinary output files
+belong to the exporter. The source check runs before export; filesystem changes between that
+check and a write still require exporter-side revalidation.