fix(a2a): stop the bus read path returning 200 with silence - #2390
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Three distinct ways GET /api/a2a/bus/messages answered "success, nothing
here" when the truth was "your request was wrong", all measured against the
live proxy:
channel=all -> 200, zero messages
channel=doesnotexist -> 200, zero messages (byte-identical)
since_id=2430 -> silently dropped; 500 messages from id 1890
`all` is the all-threads idiom the raw bus and `taosmd a2a-watch` document,
and it exists precisely so a reader cannot miss a thread created after it
started. On this proxy it was forwarded as a thread literally named "all",
matched nothing, and returned 200. An agent following our own onboarding
guide against the path we are about to recommend to every new agent got a
permanently silent bus and a success code confirming it.
The cursor case is the same shape: an ignored param is indistinguishable
from one that works, so an incremental reader re-read the whole window on
every poll while believing it held a cursor.
- `all` and `*` read every thread (spelled "omit thread" on the bus)
- an unrecognised query param is a 400 naming the accepted set, never a
silent no-op
- an empty result for a NAMED channel reports channel_known, so a typo is
distinguishable from a quiet channel; the probe fails OPEN so an
unreachable bus never accuses the caller of a typo
- `thread` accepted as an alias for `channel` (the raw bus's own name)
- `since` documented and validated as a message ts, not an id
Reported by @taOSmd-dev while verifying the authenticated read path. Their
report also said `since=` was ignored; measured, it is not -- the raw bus
does honour it, and the test asserting that passes both before and after,
so it is deliberately not counted among the fixes.
All 7 discriminating tests fail against the unfixed route.
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📝 WalkthroughWalkthroughChangesA2A bus message reads
Estimated code review effort: 3 (Moderate) | ~20 minutes Mergeability Score: 🟡 Moderate · up to The read endpoint still accepts non-finite cursor values and forwards them, which can produce invalid or unpredictable incremental reads instead of a clear client error. Merge should wait for validation to reject these values with HTTP 400. Sequence Diagram(s)sequenceDiagram
participant Client
participant bus_messages
participant Bus
Client->>bus_messages: Send channel, thread, limit, or since query
bus_messages->>bus_messages: Validate parameters and selectors
bus_messages->>Bus: Read messages with validated filters
Bus-->>bus_messages: Return messages
bus_messages-->>Client: Return messages or HTTP 400
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| status_code=400, | ||
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| channel = request.query_params.get("channel") or request.query_params.get("thread") or "" |
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WARNING: Silent parameter override when both channel and thread are provided
channel = request.query_params.get("channel") or request.query_params.get("thread") or "" silently prefers channel when both are present. A caller passing ?channel=build&thread=ops would query the bus for thread=build with thread=ops silently dropped. This is undocumented and could mask bugs in clients that pass both params.
Reply with @kilocode-bot fix it to have Kilo Code address this issue.
| except Exception as exc: # noqa: BLE001 | ||
| logger.warning("A2A bus channel probe failed (%s): %s", bus, exc) | ||
| return True | ||
| channels = data.get("channels", []) if isinstance(data, dict) else [] |
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WARNING: _channel_exists does not fail open on non-dict JSON responses from the bus channel list
If the bus returns HTTP 200 with a non-dict JSON body (e.g., {"error": "..."}), data.get("channels", []) returns [] and channel_known=False. The "fails open" guarantee only applies to transport/network failures (line 211), not to unexpected payloads. A reachable bus returning an error payload could falsely mark valid channels as unknown, defeating the typo-distinction feature.
Reply with @kilocode-bot fix it to have Kilo Code address this issue.
Code Review SummaryStatus: No Issues Found | Recommendation: Merge Files Reviewed (2 files)
Previous Review Summaries (3 snapshots, latest commit a17183d)Current summary above is authoritative. Previous snapshots are kept for context only. Previous review (commit a17183d)Status: No Issues Found | Recommendation: Merge Files Reviewed (1 file)
Previous review (commit 2d95618)Status: No Issues Found | Recommendation: Merge Files Reviewed (2 files)
Previous review (commit 0ab9712)Status: 2 Issues Found | Recommendation: Address before merge Overview
Issue Details (click to expand)WARNING
Files Reviewed (3 files)
Reviewed by step-3.7-flash · Input: 89.8K · Output: 19K · Cached: 172.9K |
…ead contract The existing test asserted bus_messages 400s on channel=*, with the rationale 'all-threads is stream-only'. That was true only because bus_messages had not implemented all-threads, not because reading every thread here was unwanted: the stream endpoint has always accepted * and forwarded no thread param. The inconsistency pushed callers toward 'all', which silently matched a thread literally named 'all' and returned an empty 200 forever. Also documents the read contract in docs/agent-coordination.md, since this is the path every new agent is told to use.
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Actionable comments posted: 1
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Inline comments:
In `@tinyagentos/routes/a2a_bus.py`:
- Around line 166-173: Update the since_raw parsing logic in the route to reject
non-finite float values such as nan, inf, and -inf with the existing HTTP 400
error response before calling the bus; add coverage for all three inputs and
verify no bus request is made.
🪄 Autofix
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
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changelog.d/bus-read-silent-empty.mddocs/agent-coordination.mdtests/test_a2a_bus.pytests/test_routes_a2a_bus_stream.pytinyagentos/routes/a2a_bus.py
…ailer works The guard documents a "Removes-Intentionally:" trailer as the way to waive a deliberate deletion, but the workflow only listened for opened/synchronize/ reopened. Adding the trailer by editing the PR body therefore never re-ran the gate, and re-running the failed job replays the stale event payload carrying the old body -- so the waiver was unreachable without an unrelated code push. store-wiring-gate.yml already carries this exact line and comment for the same reason. Proven both ways against this PR's own violation: without PR_BODY the script exits 1 naming the symbol, with the trailer it prints the waiver and exits 0.
All three are the same defect this PR exists to fix, and two of them were
reintroduced by the fix itself -- worth stating plainly rather than folding
quietly.
1. channel + thread disagreeing was a silent drop. `thread` is an ALIAS for
`channel`, so passing both with different values has no correct reading, and
preferring one silently reads a channel the caller did not ask for. Now a
400 naming both values. Identical values stay accepted -- with a paired test,
so the check cannot pass by rejecting every request that carries the alias.
2. `since` accepted non-finite cursors. float() takes "nan", "inf" and
"-inf"; a NaN cursor makes every bus-side comparison false, so the reader
gets an empty window and a 200 confirming it, forever. That is exactly the
silence the cursor validation was added to end. Now a 400.
3. _channel_exists only failed open on TRANSPORT failure. A bus answering 200
with an error body left the channel list empty and reported every channel as
unknown -- accusing the caller of a typo because of a fault on the bus side.
It now fails open on any payload it cannot read, discriminating on the
`channels` KEY rather than on the list being empty, so a bus that genuinely
knows no channels still reports unknown (pinned by its own test).
Red-first: the three defect tests fail against the previous commit's route
("accused a typo on payload {'error': 'bus is having a bad day'}"), the two
control tests pass both before and after by design. 39 green across all three
bus test files.
Found by kilo (1, 3) and CodeRabbit (2) -- all three accepted.
Bot round adjudication (kilo + CodeRabbit, head a17183d)All three findings ACCEPTED and fixed in 86dab57. They are all the same defect this PR exists to fix, and two of them I reintroduced through the fix itself, which is worth saying out loud rather than folding quietly. 1. kilo, Paired control test: 2. CodeRabbit, 3. kilo, The discrimination matters and is pinned: it keys on the Red firstThree defect tests fail against the previous commit's route: The two control tests ( Green: 39 passed across Note on bot status for the record: CodeRabbit's earlier pass on this PR read "Review rate limited", which is a fake green and was not counted. This round it produced finding 2, which was real. |
…ct) into first-boot identity Both landed after this branch was cut and both touch agent_registry_store.py, so the deleted-symbols gate correctly reported that merging without this would delete 19 symbols -- which is precisely the silent-deletion case that gate exists to catch.
1 participant
What
Three distinct ways
GET /api/a2a/bus/messagesanswered "success, nothing here" when the truth was "your request was wrong". All three measured against the live proxy before the fix:channel=allchannel=doesnotexistchannel=build&since_id=2430Why it matters now
This is the read path we are about to tell every new agent to use instead of the raw
:7900bus.allis the all-threads idiom the raw bus andtaosmd a2a-watchdocument, and it exists precisely so a reader cannot miss a thread created after it started. On the proxy it was forwarded as a thread literally namedall, matched nothing, and returned 200. An agent following our own onboarding guide gets a permanently silent bus and a success code confirming it.The cursor case has the same shape: an ignored param is indistinguishable from one that works, so an incremental reader re-reads the whole window every poll believing it holds a cursor.
Changes
alland*read every thread (spelled "omit thethreadparam" on the bus)channel_known, so a typo is distinguishable from a quiet channel — the probe fails open, so an unreachable bus never accuses the caller of a typothreadaccepted as an alias forchannel(it is the raw bus's own name for the same concept)sincedocumented and validated as a messagets, not an idchannel_knownis additive and the probe only runs when the result is empty and a specific channel was named, so the normal read stays at one bus call. The only frontend caller (A2aBusPanel.tsx) passeschannel+limitand is unaffected.Red first
All 7 discriminating tests fail against the unfixed route:
15 passed with the fix.
One correction to the report
Reported by @taOSmd-dev while verifying the authenticated read path. Their report also said
since=was silently ignored. Measured: it is not — the raw bus does honour atscursor.test_since_is_forwarded_as_the_cursorpasses both before and after, so it is deliberately not counted among the fixes. The real footgun there is thatsincetakes atswhile everyone reaches for an id, which the new 400 now says out loud.Summary by CodeRabbit
New Features
channel=allorchannel=*.threadas an alias forchannel.sinceparameter.Bug Fixes
Documentation
Deleted-symbols waiver
TestMessagesSincePassthrough.test_messages_rejects_wildcard_channelis renamed, notdropped: it becomes
test_messages_wildcard_channel_reads_all_threadsin the same class,asserting the corrected contract (
channel=*-> 200 all-threads, matchingtest_stream_wildcard_channel_all_threadson the sibling stream endpoint). The old namepinned the behaviour this PR deliberately changes, so the assertion could not survive under
its old name. Coverage of the selector is not reduced. The docstring on the renamed test
records why the previous rationale ("all-threads is stream-only") was stale.
This is the first time the guard's waiver trailer has actually been exercised in CI, and it
exposed that it could not be:
deleted-symbols-gate.ymltriggered only onopened/synchronize/reopened, so a trailer added by editing the PR body never re-ran the gate,
and re-running the failed job replays the stale event payload with the old body. Fixed here
with the same
types: [opened, synchronize, reopened, edited]line and comment thatstore-wiring-gate.ymlalready carries for its own waiver.Removes-Intentionally: tests/test_routes_a2a_bus_stream.py:TestMessagesSincePassthrough.test_messages_rejects_wildcard_channel