Debriefing
Watches your competitors' pages, pricing, changelogs and hiring, then writes the brief with what changed and what to do
Diffing a competitor's pricing page on a cron and asking a model what changed is genuinely an afternoon. changedetection.io will do the watching for you before you write a line. The gap is everything between a diff and a brief. Most page changes are noise: a rotated testimonial, a reordered nav, a CDN hash. Deciding which changes are real, tying them to hiring and funding signals, and turning that into three sentences a founder acts on is judgement encoded over many iterations. Build it and your first month is mostly you deleting alerts about nothing.
Build verification: not recorded. How we judge buildability
What you give up
- noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves
- horizon watch, meaning the substitutes and new entrants you did not think to add to the list
- the non-page signals stitched into the same brief: hiring, funding, traffic and LinkedIn movement
- the analytical step from what changed to why it matters to what to do next
- an archive going back far enough that a change reads as a trend rather than an event
Why people still pay
Because a diff is not intelligence. The hard part is not fetching a pricing page every week, it is knowing that this particular change matters and the other eleven do not, then saying so in three sentences a founder can act on before a Monday call. That judgement lives in accumulated history and a lot of tuning against false positives. It also survives being ignored: a brief that arrives whether or not you remembered to look is worth more than a script you stop reading in week three.
Your build guide
The stack, security requirements, and agent rules for a focused replacement.
Before you start
- A Python virtual environment, writable input/output directories and sufficient disk for both originals and outputs. Bind the service to localhost.
- Implementation components: Python, FastAPI and server-rendered HTML with HTMX for a local interface. SQLite for manifests and job state, with an explicit worker process and immutable source files. HTTP crawling with HTML parsing and an optional bounded Playwright renderer for user-authorized sites.
- Scope boundary: noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves; horizon watch, meaning the substitutes and new entrants you did not think to add to the list
Use these project rules and optional skill references alongside the prompt. Review each skill before adding it to your agent; the AGENTS.md export includes the same guidance.
Optional external skill: seo-audit — Investigate crawlability, indexing, page metadata, internal linking and on-page content issues. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Optional external skill: modern-python — Set up Python projects with pyproject.toml, dependency management, linting, typing and automated checks. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Optional external skill: agent-browser — Automate browser interaction using accessibility snapshots, element references and reproducible navigation workflows. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Project rule — data model: competitors, approved URLs, fetch snapshots, normalized text, diff exclusions and source-linked briefs
Project rule — preserve this invariant: Never replace a prior snapshot with a failed fetch; summaries distinguish observed changes from speculative business implications.
Project rule — acceptance evidence: A rotated timestamp produces no alert after an exclusion rule; a changed pricing paragraph links to both dated snapshots and the exact diff.
Implementation plan
Phase 1
Scope and fixtures. Implement this bounded workflow: Fetch selected public competitor pages on a bounded schedule, compare meaningful text changes and create a reviewed digest. Let the user exclude repeated headers and volatile regions before optional AI summarization. Record prerequisites, select representative user-owned fixtures and document the unsupported features: noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves; horizon watch, meaning the substitutes and new entrants you did not think to add to the list
Phase 2
Durable model. Model competitors, approved URLs, fetch snapshots, normalized text, diff exclusions and source-linked briefs Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Never replace a prior snapshot with a failed fetch; summaries distinguish observed changes from speculative business implications.
Phase 3
Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals.
Phase 4
Permissions and integration failure. Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content from logs. Constrain crawl hosts, block private-network URLs and redirect pivots, and respect crawl delays and access restrictions. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
Phase 5
Portable handoff. Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
Phase 6
Acceptance scenarios. A rotated timestamp produces no alert after an exclusion rule; a changed pricing paragraph links to both dated snapshots and the exact diff. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.
WORKING SLICE Fetch selected public competitor pages on a bounded schedule, compare meaningful text changes and create a reviewed digest. Let the user exclude repeated headers and volatile regions before optional AI summarization. Build this scoped Debriefing-inspired workflow with a documented data model and visible failure states. Architecture - Python, FastAPI and server-rendered HTML with HTMX for a local interface. - SQLite for manifests and job state, with an explicit worker process and immutable source files. - HTTP crawling with HTML parsing and an optional bounded Playwright renderer for user-authorized sites. Prerequisites and limits A Python virtual environment, writable input/output directories and sufficient disk for both originals and outputs. Bind the service to localhost. Outside this release: noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves; horizon watch, meaning the substitutes and new entrants you did not think to add to the list Data model and correctness competitors, approved URLs, fetch snapshots, normalized text, diff exclusions and source-linked briefs Invariant: Never replace a prior snapshot with a failed fetch; summaries distinguish observed changes from speculative business implications. Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals. Security and privacy Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content from logs. Constrain crawl hosts, block private-network URLs and redirect pivots, and respect crawl delays and access restrictions. Recovery and export Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. Implementation order 1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Fetch selected public competitor pages on a bounded schedule, compare meaningful text changes and create a reviewed digest. Let the user exclude repeated headers and volatile regions before optional AI summarization. Record prerequisites, select representative user-owned fixtures and document the unsupported features: noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves; horizon watch, meaning the substitutes and new entrants you did not think to add to the list 2. Phase 2 — Durable model. Model competitors, approved URLs, fetch snapshots, normalized text, diff exclusions and source-linked briefs Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Never replace a prior snapshot with a failed fetch; summaries distinguish observed changes from speculative business implications. 3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals. 4. Phase 4 — Permissions and integration failure. Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content from logs. Constrain crawl hosts, block private-network URLs and redirect pivots, and respect crawl delays and access restrictions. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results. 5. Phase 5 — Portable handoff. Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README. 6. Phase 6 — Acceptance scenarios. A rotated timestamp produces no alert after an exclusion rule; a changed pricing paragraph links to both dated snapshots and the exact diff. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder. Acceptance A rotated timestamp produces no alert after an exclusion rule; a changed pricing paragraph links to both dated snapshots and the exact diff. Use real source data or clearly labeled fixtures. Explain unsupported input and provider failures; do not fabricate analytics, delivery receipts, accuracy claims or security guarantees. Optional agent guidance Optional external skill: [seo-audit](https://github.com/coreyhaines31/marketingskills/blob/main/skills/seo-audit/SKILL.md) — Investigate crawlability, indexing, page metadata, internal linking and on-page content issues. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission. Optional external skill: [modern-python](https://github.com/trailofbits/skills/blob/main/plugins/modern-python/skills/modern-python/SKILL.md) — Set up Python projects with pyproject.toml, dependency management, linting, typing and automated checks. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission. Optional external skill: [agent-browser](https://github.com/vercel-labs/agent-browser/blob/main/skills/agent-browser/SKILL.md) — Automate browser interaction using accessibility snapshots, element references and reproducible navigation workflows. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission. Project rule — data model: competitors, approved URLs, fetch snapshots, normalized text, diff exclusions and source-linked briefs Project rule — preserve this invariant: Never replace a prior snapshot with a failed fetch; summaries distinguish observed changes from speculative business implications. Project rule — acceptance evidence: A rotated timestamp produces no alert after an exclusion rule; a changed pricing paragraph links to both dated snapshots and the exact diff.
$ open in your agent (prompt prefilled, you press enter), copy the prompt or copy or download AGENTS.md
prompt copied. want to know what dies next week?
new verdicts + top votes, weekly. free. one-click out.
Alternatives to building your own
no votes, no pay-to-list · just what's real
Debriefing pricing
starter$80/mo · monthly · $960/yr
free tierNo standing free plan, but the first debrief is free and arrives in 5 to 10 minutes.
pricing source checked 2026-08-10 · pricing source ↗
Questions about Debriefing
Can you build your own Debriefing with AI?
Partly. Diffing a competitor's pricing page on a cron and asking a model what changed is genuinely an afternoon. changedetection.io will do the watching for you before you write a line. The gap is everything between a diff and a brief. Most page changes are noise: a rotated testimonial, a reordered nav, a CDN hash. Deciding which changes are real, tying them to hiring and funding signals, and turning that into three sentences a founder acts on is judgement encoded over many iterations. Build it and your first month is mostly you deleting alerts about nothing.
What does the Debriefing build prompt cover?
The prompt starts with this scope: Fetch selected public competitor pages on a bounded schedule, compare meaningful text changes and create a reviewed digest. Let the user exclude repeated headers and volatile regions before optional AI summarization. Full-product capabilities excluded from the comparison include: noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves; horizon watch, meaning the substitutes and new entrants you did not think to add to the list; the non-page signals stitched into the same brief: hiring, funding, traffic and LinkedIn movement. Follow the implementation plan and its prerequisites before expanding the build.
How do I use the prompt, AGENTS.md and agent skills?
Start with the Debriefing prerequisites and stack, then copy the prompt into your coding agent. Save the project rules as AGENTS.md in the project root. Linked skills are optional packages or source instructions for specific tasks; review their current contents and install only those matching the chosen stack. A skill does not supply API credentials or verify the finished app.
How long will this Debriefing project take?
The catalogue estimate is multi-day for the limited scope. Setup, integration approvals, debugging, deployment and ongoing maintenance can add time. This is an estimate, not a delivery guarantee.
What would I give up by replacing Debriefing?
noise filtering, which is the actual product: most diffs are rotated testimonials and changed asset hashes, not competitive moves; horizon watch, meaning the substitutes and new entrants you did not think to add to the list; the non-page signals stitched into the same brief: hiring, funding, traffic and LinkedIn movement; the analytical step from what changed to why it matters to what to do next; an archive going back far enough that a change reads as a trend rather than an event. Because a diff is not intelligence. The hard part is not fetching a pricing page every week, it is knowing that this particular change matters and the other eleven do not, then saying so in three sentences a founder can act on before a Monday call. That judgement lives in accumulated history and a lot of tuning against false positives. It also survives being ignored: a brief that arrives whether or not you remembered to look is worth more than a script you stop reading in week three.
What price is this guide comparing against?
The recorded Starter plan is $80/mo (monthly), checked 2026-08-10. Check the linked pricing source before buying. Building your own also has hosting, API and maintenance costs; the recorded amount is not a guaranteed saving.
What can I use instead of building Debriefing?
changedetection.io: Tells you a competitor's pricing page moved. Deciding whether that mattered is back to being your job. Check each option's license, hosting needs and feature limits.