dsh-observer

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Evidence-based execution diagnostics for DeepSeek Harness. The plugin derives replayable findings from the durable Session log and adds a Diagnostics view beside Chat and Trajectory.

The initial rules intentionally make narrow claims:

• repeated consecutive Tool calls with identical canonical execution arguments; Bash/Pwsh description text is excluded because Harness documents it as presentation-only;
• repeated Tool failures with the same normalized error evidence, including structured Tool errors and the stable non-zero/signal markers emitted by Harness Bash/Pwsh tools;
• whole-session counts for Turns, Steps, model calls, Tool calls, failures, retries, and provider-reported tokens.

Every finding carries its source event range. Time and token values describe observed work; the plugin does not label them as proven waste or claim a semantic root cause.

Architecture

SessionEvent log
      ↓
observerDiagnostics projection
      ↓
bounded DiagnosticIssue[]
      ↓
Diagnostics conversation view

The package is one installable Harness bundle with two compile-time faces:

• the Host plugin registers a synchronous, JSON-serializable projection unit on ctx.sessionProjections;
• the browser plugin registers one conversation.view entry and reads the projection through the framework-provided useProjection hook.

SessionTelemetryBackend is not involved. Observer remains compatible with the deployment's existing OTel or other telemetry backend.

Development

Requirements match Harness: Node ^22.19.0 || >=24 and pnpm.

pnpm install
pnpm run check
pnpm run build

The repository develops against the public Harness 0.1.0-rc.6 packages. Runtime peer ranges begin at 0.1.0-rc.5, matching the adjacent Harness checkout used to establish this scaffold, and accept newer pre-1.0 builds.

To try the local checkout from a sibling DeepSeek Harness checkout:

pnpm dsh plugin --profile web add ../dsh-observer
pnpm dsh --profile web --dump-config
pnpm dsh --profile web

The first command changes the selected local profile. Use a disposable profile if you do not want to alter an existing setup.

Install from GitHub

Git dependencies receive source files, so this package declares a prepare build. pnpm 10+ requires the user to allow that build explicitly. Pin a reviewed commit, follow the build-allowance instruction printed by pnpm, then retry:

dsh plugin --profile web add github:lfc162874/dsh-observer#<commit>

For registry publication, remove private: true, choose the intended license, run pnpm run check, and inspect pnpm run pack:check before publishing.

Configuration

The bundle inserts these defaults; a later profile patch can replace the row's complete config value:

- id: observer
  name: dsh-observer
  config:
    repeatCallThreshold: 3
    repeatedErrorThreshold: 2
    maxIssues: 50

All thresholds must be integers. Detection thresholds must be at least 2; maxIssues must be at least 1. Invalid values fail during plugin load.

Model Experience

None. The plugin reads committed events and publishes a client projection. It does not add prompts, messages, tools, schemas, or injected context.

KV Cache effect

None. Observer does not assemble or send provider requests.

Known Limitations and Deferred Work

• The first loop rule covers exact consecutive calls. Cyclic A → B → A → B and result-similarity analysis are deferred until labelled fixtures define acceptable false-positive rates.
• Repeated-error matching removes ANSI control sequences and normalizes whitespace but otherwise remains exact. Shell exit status uses the public @deepseek-ai/dsh-shell parser; the rule deliberately does not erase paths, line numbers, or domain-specific identifiers.
• Diagnostics-to-Trajectory navigation is deferred because the current Trajectory view has no public event-sequence anchor protocol.
• Projection payloads are capped by maxIssues; older findings fall out of the view while aggregate counts remain whole-session values.