feat(tasks): make cross-project dependencies bidirectional

The :blocked: tag only marked the waiting side, so a blocker could stay unaware it was holding up another project: the dependency was visible to the one project that couldn't act on it and invisible to the one that could. This closes that gap. Setting :blocked: now requires a reciprocal inbox-send to the blocker, which files the work with a :BLOCKS: <project>: <what> property on its side. open-tasks.org surfaces :BLOCKS: tasks first, since clearing one unblocks another project (the highest-leverage pick), the mirror of pulling :blocked: tasks out of the cascade. Inbox process mode recognizes the blocking-dependency handoff shape, and the convention documents the resolution flow (drop :BLOCKS:, notify the waiter, who lifts :blocked:).

This works for any project pair, since the convention (todo-format.md) and the surfacing (open-tasks.org) live in the shared rule and workflow layer, not in one project.

Claude-Session: https://claude.ai/code/session_017PtX1nt1rtYVATuzmzBS4f

1 files changed, 2 insertions, 0 deletions

diff --git a/.ai/workflows/inbox.org b/.ai/workflows/inbox.org
index c442d17..f3d400a 100644
--- a/.ai/workflows/inbox.org
+++ b/.ai/workflows/inbox.org
@@ -114,6 +114,8 @@ The item extends a task already filed. Update the parent TODO's body with a date
 ** File as TODO
 Substantive but waits, or needs design/triage before implementation. Add the TODO under =* <Project> Open Work= with priority + tags per the priority-scheme check (core §6). Body summarizes the proposal and links the inbox content if it's been moved to =docs/design/=. Delete the inbox file (or move it to =docs/design/= first if the content survives).
 
+*Blocking-dependency handoff.* A special shape: another project sends a note that *this* project's work is blocking one of theirs ("your task X is blocked on us — we need Y"). File or link the owning task and add a =:BLOCKS: <their-project>: <what>= property to it (see the cross-project dependency convention in =todo-format.md=). The =:BLOCKS:= marker makes =open-tasks.org= surface that task *first*, since clearing it unblocks the other project. Dedup against an existing task rather than filing a duplicate. When the work later lands, drop =:BLOCKS:= and notify the waiting project (=inbox-send <their-project> --text "Delivered: <what> — you're unblocked."=) so it can lift its own =:blocked:=.
+
 ** Defer
 Rename in place to =inbox/PROCESSED-<original-filename>= and add a brief comment line at the top: =# Deferred YYYY-MM-DD: <condition>=. Don't accumulate deferred items indefinitely — sweep them on a future process pass when the condition is met or the deferral has aged out.