Address review on the hook-bridges PR — two composability/compatibility bugs
in both the CC and Codex bridges:
1. A hook that only attaches additionalContext (no block/deny) returned
`allow`/`accept` WITHOUT calling next(), short-circuiting every later
agent/prompt-submit / tools/post-execute listener. A policy/sandbox plugin
registered after the bridge never saw the prompt. Now the context-only path
delegates via next() and folds its context onto the downstream decision
(concatContext): a downstream block/deny still wins and carries the bridge
context; a downstream allow/accept keeps its own content rewrite and gains
the context. Only a real hook deny/block short-circuits.
2. CLAUDE_PROJECT_DIR was empty in the default ACP wiring (no projectDir
configured), breaking common unmodified hooks that reference
$CLAUDE_PROJECT_DIR. It now defaults per-run to the agent's session
workspace (the same cwd the hook runs in); an explicit config.projectDir
still wins.
Regression tests per bridge: a later listener blocks a prompt a context-only
hook allowed; both contexts survive when the downstream also adds one; the
default CLAUDE_PROJECT_DIR reaches the hook. Each proven red on the pre-fix
code.