Debugging a run

Reading a run

Each verb below prints one compact line per run or per event and has a flag that opens the part you want, so a forty-node run reads without loading the whole journal. You read in this order and stop when you hold the failing node and the wrong value.

• If you want to know what ran, or whether your trigger fired since the change: weft executions --limit 10 --phase fire. One line per run: execution id, status (running, waiting_for_input, completed, failed, cancelled), phase, the start time in UTC, the project id, the entry node (the trigger that fired), the tags. An activate, a resync or an infra start creates setup runs, phases trigger_setup and infra_setup; --phase fire hides them. --project <id> narrows to one project. A run whose trigger has recorded: false is listed only if it failed (with the step that failed and why, nothing before it) or reported a cost or asked weft for something on its behalf, so a route that answered and left nothing here may simply be unrecorded: weft status shows how many runs each trigger started in the last minute or two and how many failed, which is how you confirm its runs happen.
• If a run failed and you want the reason: weft logs <execution-id>. It prints what the run's nodes wrote and every failure the journal recorded, as error and warn lines. A line about one node names it (and the loop iteration, llm#3:); a line about the run itself (the run failing, a cancel) names none: [2026-09-02 21:36:47] error llm: node failed: the service answered 401 .... It is the last 1000 lines and says so when the run wrote more; --limit raises that up to 20000, higher is refused. For most failures this is enough and you never open the events. (no logs: ...) means the run wrote nothing and recorded no failure: it did not fail, so you check its status.
• If you want the values on the wires: weft events <execution-id>. One line per event: UTC time, kind, node, then everything the row carries as key=value, each cut to a screen's width (input= on node_started, output= on node_completed, error= on node_failed, reason= on a skip or a cancel, token= on a suspension, and so on). You narrow before you read: --kind failed for the failures (a substring matches, so this catches node_failed and execution_failed), --kind node_skipped for what did not run and why, --node <id> for every event on one node, --iteration 3 for the fourth time round a loop (counted from 0; 3.0 is the first iteration of a loop inside it, outermost first).
• If a value on one of those lines is cut off: it was cut to fit the screen, not stored short. weft events <execution-id> --node <id> --full prints it whole, and --json gives you the replay rows for grep or jq. No value a run recorded is unreadable, so you never report one as unreadable.
• If a node did not run: its node_skipped line carries the reason. did_not_flow: the node's _should_flow said no. flow_closed: nothing ever answered its _should_flow, so walk to whatever drives that wire. required_input_closed names the input that arrived closed, so walk to that node's line. every_input_closed and one_of_group_closed are the same story for a node with no required inputs and for a @require_one_of group. scope_skipped names the group or loop whose _should_flow said no, taking this node with it: walk to that container. (A group input arriving closed is not this: it passes through to the nodes inside that read it, and they carry their own reason.)
• If a Debug shows output= empty: correct, a Debug has no outputs. Its value is on its node_started line as input=, or weft events <execution-id> --node <debug id>.
• If a past run shows no values at all: a run's rows say what happened, not what it meant; the editor works out every input and output by replaying those rows against the code the run ran, so a run whose code [the daemon] no longer holds shows every node with no values, and the run itself says why. The empty graph is not "the node produced nothing" and not a viewer bug. The code is kept as long as any run points at it, so this is rare. If the files are still on disk, weft build puts the program back under the hash the run names and the run reads as it did. If not, the run is readable only as its shape, and weft clean <execution-id> removes it.
• In VS Code with the weft extension: the Executions view, "View in Graph" replays the run in the graph, values on every wire; Debug nodes render their latest value inline. For the full editor surface (inspector, action bar, targets, everything clickable), go and read the weft-editor skill.

The debugging playbook

1. It does not compile. Read the diagnostics: line:column message, a stable slug, and the message names the fix. You fix what it names; you never route around a diagnostic. weft validate --file src/main.weft < src/main.weft re-checks without building. A diagnostic naming the catalog (an enrichment error, an unknown field, "a stale base_catalog copy") means the stdlib copy lags the installed weft: weft catalog update, then re-check, before anything else.
2. A run failed. weft logs <execution-id> names the node and the error. If that is not enough, weft events <execution-id> --node <that node> shows the values that reached it, on its node_started line. For the compiler error slugs, go and read the weft-language skill. A node's own error text is written by the node's author. A node error saying it has no connection picked is [the runtime tier] firing at execution, not a source bug: you pick a stored connection yourself (weft connect --node <id> --grant <grant>) or send the user to the node's Connect button / weft connect in their terminal, then run again. A failure saying the worker running '<node>' went away while it was running means the worker of a durable run died mid-step: weft does not run a step again once its start is on record, because the step may have partly happened. Check what it did outside (the email, the row, the post), then, if it has to happen again, start a run at that step by hand: weft run --from <node>=<inputs>, with the inputs from weft events <execution-id> --node <node> --full. If the message says went away while it was reading a stream instead, the items it read are gone from the stream, so --from cannot hand them back: check what it did, then run the whole execution again.
3. A value is wrong, not failed. Work upstream from the output: open the run, look at the top-level groups, find the first whose output is already wrong, descend, repeat. When you hold the concrete failing case, iterate on that one step (build, run, look) and feed the earlier stages' passing examples through again.
4. Suspended. Expected for human-in-the-loop: nothing is wrong. A suspended run is alive and costs nothing: the HumanQuery parks, the worker exits, and the answer resumes it. The person answers in the browser extension (built with ./setup.sh --browser --no-sign). If nobody should have been asked, the bug is the _should_flow that routed into the person.
5. Cancelled. Read the reason on execution_cancelled. Cancelled by user is a person: the Stop button, weft stop, a project deactivate or wipe, or a cancel through a signal token. Stopped by execution <execution-id> (tag <tag>) means another run asked the engine to stop everything carrying that tag: look at that run, and if no sibling was supposed to stop this one, the bug is in whichever node tagged and stopped it (weft executions shows each run's tags, so you see which runs shared it). Caller disconnected means the live caller this run was answering dropped its connection. the worker running this run went away; a fast run lives in its worker's memory, so it is not run again means a fast run lost its worker (a crash, a machine gone): check what it did outside, then start it again (let the trigger fire again, or fire it by hand: weft bake, then weft run --fire <trigger>=<payload>, with the payload on the trigger's node_kicked line in weft events <execution-id>), and if the trigger's runs have to carry on after a worker dies, set durable: true on it. A durable run whose worker stops or dies is never cancelled: another worker picks it up from its record, and only the step that was running fails (item 2). the run had to leave the copy of the program running it (...), and it cannot be suspended: <why> means its worker was stopping and this run could not move to another one; the <why> names the reason: its trigger has recorded: false, its route does not have outlivesCaller, or a bus between its nodes was open. Check what it did outside, then start it again the same way as a fast run that lost its worker. Anything else is the runtime's own reason, printed as words.
6. Stuck. The engine proved nothing can proceed; that is a graph-shape bug (a wire the compiler could not catch). The execution_failed line names every firing left holding a pulse and the wired ports it never received (theirs has value, still waiting on go): walk to whatever should have driven the missing port.
7. Nothing ran. Nothing reached the branch: check that the trigger that should have fired is activated, then walk from it down to the first _should_flow or required input that closed.
8. Too much is running. The one failure nobody reports, because nothing errors: runs accumulate and the only symptom is a list that keeps growing. Every live connection is its own run for as long as the caller holds it, so a page anyone can open, or a client that reconnects by itself, can leave one behind per visit. weft executions is the check, and what you look at is the STANDING count of runs still going, not whether the one you started finished. Drive the thing, close it, look again: the count comes back down, or you have found a leak. Several runs of one trigger that never end is a finding you report, with the count and how long they have stood.
9. A timer or a wake that never arrived. A wake the receiver refuses for good is dropped once, with one error in weft daemon logs naming it, the status and the answer (on a local install: any 4xx except 408 and 429; the listener answers a wake it cannot read 200 with dropped and logs it). A failure that may pass (a 5xx, 408, 429, no answer) is sent again later, waiting longer each time. So a wait that never woke is read in weft daemon logs.
10. [the daemon] unreachable (connection refused, an editor button that does nothing). You read, never restart: weft daemon status and weft daemon logs --tail 50 say what [the daemon] is doing. Then you tell the user the symptom (the exact refusal, and what you were running) and stop; bringing [the daemon] back is their install's job. If you catch yourself typing weft daemon start, stop or restart, stop and write: "Wait. The daemon is not mine to restart." Then report the symptom.