docs(graph): timeout: 0 disables the wall-clock bound

Documents the new zero-means-unbounded rule on all five timeout fields
(settings.timeout, agent, script, llm, rag), the validator warning that
flags an explicit 0, how bounds compose outward-in across nested graph
agents, and what interrupts an unbounded step.

Graph-Agents.md

@@ -95,7 +95,7 @@ settings:
   max_loop_iterations: 100     # PER-NODE visit cap; default 100 (see below)
   log_state_snapshots: true    # log state JSON before each node executes
   validate_before_run: true    # run the graph validator on startup
-  timeout: 600                 # optional overall timeout in seconds
+  timeout: 600                 # optional overall timeout in seconds; 0 = no bound
   max_concurrency: 8           # cap on simultaneously running parallel branches; default 8
 
 reducers:                      # optional; declares how parallel branches merge writes
@@ -159,7 +159,21 @@ nodes:
   `fallback`s, so any cleanup/reporting nodes are skipped. Prefer per-node
   `timeout`s on `llm` nodes (which *do* route via `fallback`) as the
   operative bound, and treat the graph-level `timeout` as a generous
-  backstop.
+  backstop. `0` disables the bound entirely (equivalent to unset;
+  `--validate` flags the explicit `0` as an intentional choice) — for graphs
+  that must run until they complete, e.g. an end-to-end implementation run;
+  pair it with a sane `max_loop_iterations`. **Bounds compose outward-in:**
+  if this graph is run by another graph's `agent` node, that node's
+  `timeout` (default 300) still applies and will drop this graph regardless
+  of its own settings — set `timeout: 0` there too. Conversely a parent's
+  `timeout: 0` does not lift a child's non-zero `settings.timeout`; the
+  child's own executor enforces it. A root graph run directly is bounded
+  only by its own `settings.timeout`. An unbounded run ends only on
+  completion, error, or an enclosing bound; Ctrl-C is observed between
+  super-steps, and an in-flight agent step only stops when its own loop
+  observes the interrupt (a script step is killed only when its future is
+  dropped). The 300s agent default was a de-facto safety net for a wedged
+  child — `timeout: 0` is the explicit opt-out of that net.
 - **`initial_state`:** A JSON-compatible object. Values are seeded into
   state before any node runs and are referenced from any node via `{{key}}`
   templates.
@@ -243,7 +257,7 @@ research_topic:
   type: agent
   agent: deep-researcher          # name of an existing Coyote agent
   prompt: "Research {{topic}}"    # interpolated against state
-  timeout: 600                    # optional, in seconds (default 300)
+  timeout: 600                    # optional, seconds; default 300, 0 = no bound
   inputs:                         # optional; only when the child is a GRAPH agent
     max_parallel: "{{inner_width}}"  # seeds the child's initial_state (see below)
   teammates: false                # optional; peer messaging with concurrent siblings (see below)
@@ -258,7 +272,10 @@ research_topic:
 - **`prompt`:** The user message sent to the child agent. Templated against
   the current graph state.
 - **`timeout`:** Hard wall-clock cap. If the child agent exceeds it, the
-  whole graph fails (no built-in fallback path on agent nodes).
+  whole graph fails (no built-in fallback path on agent nodes). `0`
+  disables the bound; the child runs until it returns. Required on the
+  calling node to let a child graph's own `timeout: 0` take effect; the
+  child's non-zero `settings.timeout` still applies.
 - **`state_updates`:** Map of `state_key: "{{template}}"`. The child agent's
   final text is available inside this map as `{{output}}`.
 - **`inputs`:** Map of `child_state_key: "{{template}}"`. Each value is
@@ -396,7 +413,7 @@ route_after_parse:
   id: route_after_parse
   type: script
   script: scripts/route_after_parse.py
-  timeout: 30                     # seconds, default 30
+  timeout: 30                     # seconds; default 30, 0 = no bound
   fallback: handle_error          # optional: where to route on script failure
   state_updates:                  # applied after stdout merge
     last_run: "{{some_value}}"
@@ -571,7 +588,7 @@ grade_research:
   state_updates:
     grade: "{{output}}"
   output_schema: { ... }        # optional, see "Structured Output" below
-  timeout: 120                  # optional; node wall-clock cap in seconds (unset = no timeout)
+  timeout: 120                  # optional; node wall-clock cap in seconds (unset or 0 = no timeout)
   next: synthesize
 ```
 
@@ -639,6 +656,7 @@ A node-level `timeout` counts as a failure like any other: it routes via
 per-node `timeout`s the preferred way to bound long-running `llm` nodes.
 Unlike the graph-level `settings.timeout`, a node timeout still gives the
 graph a chance to recover or report through its `fallback` route.
+`timeout: 0` (or unset) disables the bound.
 
 ### Retries (`max_attempts`)
 
@@ -712,7 +730,7 @@ research_context:
     - https://example.com/spec
   query: "{{initial_prompt}}"   # templated; defaults to "{{initial_prompt}}"
   top_k: 5                      # optional; default = the knowledge base's own top_k
-  timeout: 120                  # optional; retrieval timeout in seconds (default 120)
+  timeout: 120                  # optional; retrieval timeout in seconds (default 120; 0 = no bound)
   state_updates:                # required in practice (see below)
     rag_context: "{{output.context}}"
     rag_sources: "{{output.sources}}"
@@ -735,7 +753,7 @@ answer:
   query an upstream `llm` node produced.
 - **`top_k`:** Number of chunks to retrieve. Defaults to the knowledge
   base's own configured `top_k`.
-- **`timeout`:** Retrieval timeout in seconds. Default 120.
+- **`timeout`:** Retrieval timeout in seconds. Default 120; `0` = no bound.
 - **`state_updates`:** Where the result goes. A `rag` node with no
   `state_updates` discards its result (the validator warns).
 
@@ -1060,6 +1078,8 @@ script node upstream.
   failed item). One failing item fails the map.
 - **Per-item timeouts.** `settings.timeout` applies to the whole
   super-step; node-level `timeout`s (llm/agent/script) apply per step.
+  `timeout: 0` on a branch's `agent`/`script` nodes is the explicit opt-out
+  for long-running chains; the item then runs until its terminal node.
 - **Shared state between items mid-run.** Items communicate via
   [teammate messaging](#teammate-messaging-in-fan-outs); results merge at
   collect.